International Rice Research Notes Vol.18 No.4

International Rice Research Notes

The International Rice Research Notes (IRRN) expedites communication among scientists concerned with the development of improved technology for rice and rice- based systems.

to help scientists keep each other informed of current rice research findings. The concise scientific notes are meant to encourage rice scientists to communicate with one another to obtain details on the research reported.

The IRRN is published quarterly in March, June, September, and December by the International Rice Research Institute; annual subject and variety indexes are also produced.

The IRRN is divided into three sections: notes, news about research collaboration, and announcements.

The IRRN is a mechanism

ISSN 0115-0944

Contents December 1993

Germplasm improvement

Genetic resources 4 Relationship among Latin American rice

breeding sites for disease evaluation 4 In vitro propagation of conserved rice

germplasm

Genetics 6 Inheritance of thermosensitivity for seedling

color in japonica variety Fan5

Breeding methods 6 Restorers and maintainers for cytoplasmic

7 Identifying restorers and maintainers for male sterile (CMS) lines in rice

cytoplasmic male sterile (CMS) lines lR62829 A and lR58025 A in Myanmar

cytoplasmic male sterile (CMS) lines lR58025 A and lR62829 A in Vietnam

sensitive genic male sterile (PGMS) lines in China

7 Identifying restorers and maintainers for

7 Identifying and evaluating photoperiod-

9 Inflorescence culture in rice

Pest resistance—diseases 10 Evolution of rice blast (BI) fungus based on

cross-fertility of Pyricularia grisea Sac. 11 Reaction of some rice germplasm to leaf blast

(BI) in Guyana

Pest resistance—insects 11 Resistance to whitebacked planthopper

(Sogatella furcifera) in rice varieties with different genes for brown planthopper (BPH) resistance

12 Field screening of rice cultivars for resistance to leaffolder (LF) (Cnaphalocrocis medinalis Guenée) and stem borer (SB) (Sesamia inferens Walker)

12 Evaluation of rice genotypes for resistance to orange-headed leafhopper (OHLH) in the Hill Zone of Karnataka, India

13 Resistance to gall midge (GM) Orseolia oryzae in Chinese rice varieties compared with varieties from other countries

14 Resistance to green leafhopper (GLH) in hybrid rice

14 Screening rice accessions for resistance to thrips

Integrated germplasm improvement—irrigated 15 Evaluation of rice varieties for lowland cultivation

16 Two newly developed glutinous rice varieties for

16 Yield performance of rice hybrids in Cuu Long

17 Kamini: a quality rice released in Bihar, India 17 Xiang-Zao Xian No. 15: a high-quality variety in

17 Performance of IRRI rice hybrids at Rice

in Papua New Guinea

Assam, India

Delta, Vietnam

Hunan, China

Research Institute (RRI), Kala Shah Kaku, Lahore, Pakistan

Integrated germplasm improvement- rainfed lowland 19 IR-Kesar: a brown planthopper (BPH)-resistant

19 Lioto, a short-duration rice variety suitable for variety for Cambodia

northern Zaire

Integrated germplasm improvement—upland 20 Brazilian Upland Rice Breeding Network: varietal

release, time span, and yield increase 21 Elite upland rice lines in Japan

Integrated germplasm improvement—tidal wetlands 22 Yield performance of some rice lines in acid

sulfate soils of Indonesia

Seed technology 23 Effect of different doses of gamma rays on

germination and survival of upland rice varieties

Crop and resource management

Soils 24 Puddling depth and soil texture influence

percolation rate (PR)

Physiology and plant nutrition 24 Characteristics of rice root growth under salt

stress

Fertilizer management—inorganic sources 25 Yield response of Basmati rice to applied P at

different soil P values 26 Effect of timing of basal N application on

transplanted rice yield and N recovery 26 Retention and movement of applied Zn in rice

soils

Fertilizer management—organic sources 27 Influence of green manure (GM) Sesbania

27 Biofertilizers enhance dissolved oxygen

28 Biomass and N content of Sesbania rostrata

aculeata on Zn and S translocation in rice

content (DOC) in water

mutant with long vegetative phase

lntegrated pest management—diseases 28 Analysis of genetic diversity and population

structure of bacterial blight (BB) pathogen in West Java, Indonesia

mycoplasma-like organisms (MLOs) of yellow dwarf (RYD) and orange leaf (ROL) in rice

30 Toxin produced by Sarocladium oryzae involved in inducing sheath rot (ShR) symptoms in rice

29 Use of DNA probes to distinguish

lntegrated pest management—insects 31 Farmers’ estimates of percent whiteheads

31 Managing thrips in the Mekong Delta, Vietnam 32 Parasitism of brown planthopper (BPH) and

green leafhopper (GLH) eggs by Anagrus flaveolus Waterhouse

33 Egg-laying behavior of African white rice borer Maliarpha separatella Ragonot

lntegrated pest management—other pests 34 Feeding behavior of parakeets on rice in Hill

region of Karnataka, India 35 Effect of selected genera of plant parasitic

nematodes on germination of rice seeds in eastern India

(WH)

Farming systems 35 Effect of preceding crops on rice yield

Socioeconomic impact

36 Impact of modern mangrove swamp rice varieties in Sierra Leone and Guinea

Research methodology

37 An empirical relationship between

38 A rapid method for screening rice-

39 Using single-site augering to determine root

N input and false smut intensity in rice

associated bacteria antagonistic to Rhizoctonia solani

distribution of rice

News about research collaboration

40 IRRI guidelines encourage marketing of hybrid rice seed to farmers

40 Thai farmers like mechanized harvesting system

41 New center for rice research in Iran 41 Potassium deficiency potentially linked with

disease problems in Vietnam 41 Weedy forms of rice present in Southeast Asia 41 China’s hybridization program benefits from

42 Chinese provincial researchers to be trained by INGER

IRRI

Announcements

42 42 43

44 44 44 44

45 45

45 45 45 45 45 46

Postdoctoral research fellowships at IRRI Rice dateline Send in your nomination for Outstanding Young Women in Rice Science Awards IRRI group training courses for 1994 Climate Change and Rice Symposium Wet seeded rice workshop 25th Meeting of the Rice Technical Working Group Temperate rice conference Rice conference for Latin America and the Caribbean McNamara Fellowship Program New IRRI publications Rice literature update reprint service Call for news New publications IRRI address

37 Lyophilized blast (BI) fungal mycelia are nonviable and suitable for international exchange

Errata

Instructions for contributors

Inside back cover

Germplasm improvement

Relationship among Latin American rice breeding sites for disease evaluation C. A. Moquete-C. and E. P. Guimarães, Centro lnternacional de Agricultura Tropical, Apartado Aéreo 6713, Cali, Colombia

Latin American countries exchange germplasm through several mechanisms, a major one being the International Network for Genetic Evaluation of Rice (INGER)-Latin America. Countries expect certain desirable traits when requesting for germplasm. One important characteristic is disease reaction. To characterize germplasm for distribution, INGER-Latin America uses a disease “hot spot,” located at the Santa Rosa Experimental Station (SRES), Villavicencio, Colombia.

released in the region through this mechanism. The efficiency of the exchange system needs to be improved, however, and the relationship among breeding sites needs to be better known. We estimated the level of coincidence among evaluations at SRES and four other breeding sites in Latin America.

breeding lines in Villavicencio and Palmira, Colombia; Cristina, Guatemala; Goiânia, Brazil; and Juma, Dominican Republic during 1991-92. We evaluated

More than 80 rice varieties have been

We tested 46 commercial varieties and

Table 1. Average disease reaction at 5 locations in Latin America. a 1991-92.

Location Bl b PB LSc Gd

Cristina 1.7** 2.7** 3.1 ns 1.8** Goiânia 2.6** 4.9** 2.3** 3.3** Juma 0.0** 2.5** 2.3** 1.4** Palmira 0.0** 0.0** 0.0** 1.2** SRES 3.4 3.7 3.4 4.0

a All values were compared with SRES, Villavicencio, using the t test. ** = difference significant at 1% probability. ns = difference not significant. b Evaluation of disease reaction was based on the Standard evaluation system for rice. BI = leaf blast, PB = panicle blast, LSc = leaf scald, and Gd = grain discoloration.

4 IRRN 18:4 (December 1993)

Table 2. Percentage of coincidence among the susceptible lines at SRES, Villavicencio, and the same lines in 2 other locations. a 1991-92.

Location BI PB LSc Gd

Cristina 33 (5) 85 (15) 27 (6) 0 (1) Goiânia 0 (2) 75 (24) 0 (3) 11 (4) SRES 100 (12) 100 (13) 100 (11) 100 (19)

a Values in parentheses refer to the number of susceptible lines.

disease reaction for leaf blast (B1), panicle blast (PB), leaf scald (LSc), and grain discoloration (Gd) using IRRI’s 1988 Standard evaluation system for rice.

Disease reaction was analyzed using the t test. Overall averages of each site were compared with that of SRES. To calculate the level of coincidence, we used only materials that were susceptible at SRES (score ³ 4). If all materials were used, the resistance reaction in a low disease-pressure site would be misleading. Percentage of coincidence was estimated as number of susceptible lines at a given location that coincide with those susceptible at SRES divided by total number of susceptible lines at SRES and the result multiplied by 100.

SRES had the highest average scores for all four diseases, except at Goiânia for PB (Table 1). Highly significant differences existed between SRES and all other sites for all diseases, except at Cristina for LSc. Palmira seemed to be a

location without disease pressure, confirming several reports about disease pressure at SRES.

We estimated the percentage of coincidence among the susceptible lines at SRES and the same lines at Cristina and Goiânia (Table 2). Palmira and Juma were not included because no lines in those places had susceptible reactions. The highest values were obtained for PB at Cristina (85%) and Goiânia (75%), suggesting a high degree of relationship of information on germplasm evaluation among the sites. Latin American countries can use data from the three sites to guide exchanges if PB is of concern. Differences in fungal races and environmental conditions can explain some of these results. The higher coincidence for PB than for B1 suggests that race and/or site by race-specific interactions are more important for B1 than for PB.

In vitro propagation of conserved rice germplasm

accessions. Another advantage is that plantlets in sterile media can be safely distributed to requesters worldwide.

A. Juliano, D. A. Vaughan, Chuan Yin Wu, and F. J. Zapata, IRRI

Some conserved rice varieties and wild rices are poorly adapted to the locations of genebanks and sometimes produce very few or no seeds. Several wild rice populations are sterile. As a consequence, seed stocks are limited for rejuvenation and distribution, and some conserved accessions are maintained in a vegetative state. In vitro propagation can be used more safely and efficiently than in vivo propagation for increasing plants of these

We conducted two experiments to determine the best protocol for in vitro propagation of conserved germplasm. The first used seeds to proliferate plantlets of wild Oryza species. The second used immature panicles of O. sativa to develop calli from which plants were regenerated.

accessions of wild rices representing O. rhizomatis (CC genome) and diploid (BB) and tetraploid (BBCC) accessions of O. punctata were used for in vitro propagation (see table). Dehulled seeds

In the first experiment, nine

Genetic sources

Proliferation of germplasm from seeds. See text for explanation.

In vitro shoot proliferation from seeds of wild rices.

IRGC a ACC. no. Species Genome Origin Ploidy level

101417 103897 103906 104064 104073 101409 104059 103410 103417

O. punctata O. punctata O. punctata O. punctata O. punctata O. punctata O. punctata O. rhizomatis O. rhizomatis

BB BB BB BB BB BBCC BBCC CC CC

a International Rice Germplasm Center.

Kenya Tanzania Tanzania Nigeria Cameroon Ghana Nigeria Sri Lanka Sri Lanka

Diploid Diploid Diploid Diploid Diploid Tetraploid Tetraploid Diploid Diploid

were surface-sterilized in 70% ethanol for 2-3 min, followed by 20% Chlorox

and inoculated into 125-ml erlenmeyer were maintained at 25 °C and 16-h were excised from 30-d-old seedlings liter at pH 5.8 (Fig. 1-A3). The seedlings (Fig. 1-A2). Hypocotyls and radicles liter, 0.1 mg IAA/liter, and 0.1 mg NAA/ 0.4% agarose and 3% sucrose at pH 5.8

tubes on sterilized MS medium plus Al). The seeds were germinated in test commercial bleach for 30 min (Fig. 1-

from multiple-shoot clusters and casein hydrolysate/liter, 2 mg kinetin/ after 70 d. Single shoots were separated plus 0.5% agar, 3% sucrose, 300 mg

An average of 4 shoots were produced flasks containing sterilized MS medium daylength.

~

transferred to a test tube containing a root induction medium (MS medium plus 0.4% agar, 6% sucrose, and 0.5 mg NAA/liter at pH 5.8) until roots were well established (Fig. 1-A4). Single shoots from multiple- shoot clusters could be repeatedly used to increase plants (Fig. 1-A7).

Plants derived directly from seeds and from seeds via in vitro culture were compared for various characters using five replications per accession. Most characters showed no differences between treatments. Number of days to flowering and maturity, however, were fewer in plantlets derived from in vitro culture due to their more advanced development than germinated seeds upon transfer to soil.

In the second experiment, we used Rayada (International Rice Germplasm Center Acc. 27588), a photoperiod- sensitive and long growth duration deepwater variety from Bangladesh. Prior to flag leaf emergence, young panicles (40-50 mm) were excised from all but the final enclosing leaf sheath (Fig. 1-Bl). These were surface-sterilized using 70% ethanol followed by 20% Chlorox commercial bleach. Immature panicles were cut into 3-10 mm long pieces and placed in petri dishes containing 20 ml callus induction medium (LS medium plus 0.8% agar, 3% sucrose, 2.5 mg 2,4-D/ liter at pH 5.8) and kept at 27 °C in the dark for 3-4 wk (Fig. 1-B2). Calli produced were transferred to a 125-ml erlenmeyer flask containing 45 ml plant regeneration medium (MS medium plus 0.6% agar, 3% sucrose, 2 mg kinetin/liter, 1 mg NAA/liter, 0.5 mg IAA/liter at pH 5.8) (Fig. 1-B3).

Regenerated plants, about 8 cm tall (Fig. 1-A3), were separated into single shoots and transferred to test tubes containing a root proliferation medium (MS medium plus 0.4% agar, 6% sucrose, 0.5 mg NAA/liter at pH 5.8) until roots were well established (Fig. 1-A4). Rooted plants were transferred to Yoshida's culture solution (Fig. 1-A5) and acclimatized in a glasshouse before transferring to soil in a nursery where photoperiod treatments were applied (Fig. 1-A6). Mature seeds were produced within 158 d after transfer to the nursery. In vitro production of plantlets can be continued until there are sufficient seed stocks of the accession (Fig. 1-A7).

IRRN 18:4 (December 1993) 5

Inheritance of thermosensitivity for seedling color in japonica variety Fan5 Dong Yanjun, Shi Shouyun, and Zhang Hongde, Crop Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021; Cheng Shihua and Sun Zongxin, China National Rice Research Institute, Hangzhou 310006, China

We isolated a mutant that is thermosensitive for seedling color in japonica variety Fan5. Expression of seedling color of Fan5 and four other japonicas was studied at temperatures of 20, 23.1, 26.1, 28, and 30.1°C in a growth chamber. Seedling color was examined after 10 d. Thermosensitive Fan5 showed variation in seedling color at different temperatures: white at 20°C, yellow-white at 23.1°C, yellow-green at 26.1°C, and green at 28 and 30.1°C. The other four japonicas were thermoinsensitive for seedling color at all five temperatures.

Crosses of Fan5 and japonica varieties and cytoplasmic male sterile (CMS) japonica line 7627 A were grown in 1991 in Hangzhou. In Oct 1992, P 1 , P 2 , F 1 , F 2 , and BC 1 populations were sown in plastic pots at 20°C.

Restorers and maintainers for cytoplasmic male sterile (CMS) lines in rice W. Wilfred Manuel and M. Rangaswamy, Rice Research Station (RRS), Ambasamudram, Tamil Nadu 627401, India

Hybrid rice can only be developed if effective fertility restorers for CMS lines are identified and maintainers are isolated to develop new CMS lines. We evaluated F 1 s of 51 hybrids, their 17 pollen parents, and 3 isogenic maintainers (B lines) of CMS lines for spikelet fertility. The experiment was laid out in a randomized block design with two replications during 1991 wet

Seedling color of thermosensitive Fan5, four thermoinsensitive japonica rice varieties, and their F1, BC1, and F2 populations grown at 20°C. Hangzhou, China.

Seedling color

Green White Material P

Parent Fan5 0 29 700 1S 37 0 N5047S 41 0 Zhenong 1S 16 0 7627 A 23 0

F 1 7001S/Fan5 15 0 N5047S/Fan5 17 0 Zhenong 1S/Fan5 21 0 7627 A/Fan5 a 9 0

BC 1 7001S/Fan5//Fan5 52 47 N5047S/Fan5//Fan5 38 29 Zhenong 1S/Fan5//Fan5 50 56 7627 A/Fan5//Fan5 44 39

F 2 7001S/Fan5 153 47 N5047S/Fan5 113 31 Zhenong 1S/Fan5 143 45

(1:1) 0.162 0.50-0.75 0.955 0.25-0.50 0.223 0.50-0.75 0.193 0.50-0.75

(3:1) 0.167 0.50-0.75 0.750 0.25-0.50 0.638 0.75-0.90

a F 2 from 7627 A/Fan5 was not tested due to poor seed setting in F 1 .

F 1 seedlings from all crosses were green, indicating that thermosensitivity for seedling color in Fan5 is recessive (see table). The segregation ratio of green to white in BC, was 1:1 and in F 2 , 3:1. Results showed a recessive nuclear gene controls thermosensitivity for seedling

color in Fan5. If the character can be transferred to CMS lines and their maintainers, it could be used as a morphological marker for purifying them by roguing green seedlings at lower temperature.

season at RRS. Each 1.7- × 0.2-m plot had a single row of 11 plants at 20- ×

Maintainer and restorer lines identifled for 3 CMS lines at RRS, Ambasamudram, Tamil Nadu, India, 1991 WS.

15-cm spacing. Fertilizer was applied at 100-50-50 kg NPK/ha and other Spikelet fertility a of hybrid

with particular CMS line recommended cultural practices were followed.

Pollen parent

replication for each genotype. Pollen ASD16 PR PR PR randomly selected plants in each ASD17 PR PR PR ASD18 PR R R

parents were classified as effective CO 37 PR R PR

restorers if spikelet fertility was more IR36 PR PR PR

than 80%, as weak or partial restorers if IR60 IR50 PR R

PR PR PR PR

20-80%, as weak maintainers if 5-20%, IR64 R PR R

and as effective maintainers if 0-5%. IET1444 PR PR PR TKM6 PR R R

Fourteen hybrids had more than 80% TKM9 PR PR PR

spikelet fertility, involving nine pollen TM4309 PR R R TNAU801793 PR PR PR

parents. These pollen parents were TNAU88013 R

identified as effective restorers for CMS ADT39 M PR PR

lines V20 A, IR58025 A, and IR62829 A (see table). These prospective restorers a R = restorer, PR = partial restorer, M = maintainer.

V20 A lR58025 A lR62829 A

Spikelet fertility was assessed on five ADT36 PR PR R


Breeding methods

Jaya PR R PR

Genetics

R PR

c 2

c 2

c 2

can be purified genetically and then used in developing hybrids.

spikelet fertility, so pollen parent ADT39 was identified as a potential maintainer for CMS line V2O A. This prospective maintainer line will be used in a backcrossing program to develop new CMS lines.

CMS lines V2O A, IR58025 A, and IR62829 A, which all have the same wild abortive cytoplasm but different nuclear genotypes, differed in maintainer and restorer frequencies. Genetic background of CMS lines seems to influence their maintaining and restoring abilities.

Restoration-maintenance behavior sometimes differed among pollen parents for CMS lines with the same cytoplasmic source, possibly because of nuclear and cytoplasmic interactions between pollen parents and CMS lines or the heterozygosity of pollen parents.

V2O A/ADT39 recorded 4.3%

Identifying restorers and maintainers for cytoplasmic male sterile (CMS) lines lR62829 A and lR58025 A in Myanmar Hla Min, Myanmar Agriculture Services, Thayawadi; Khin Than Nwe and Tin Tin Myint, Central Agricultural Research Institute (CARI), Yezin, Pyinmana, Myanmar

CMS lines IR62829 A and IR58025 A were crossed with seven high-yielding rice varieties in 1991 wet season at Hmawbi Research Station and CARI at Yezin. F 1 s and their parents were grown in 3-m rows at 20- × 20-cm spacing in 1992 dry season. Florets from each plant were collected before flowering and stained with KI solution to determine pollen sterility. Pollen sterility percentage was estimated by counting filled and unfilled grains from harvested F1 panicles.

Varieties were classified as effective maintainers of male parents if pollen fertility of the hybrid was less than 5%. Male parents were identified as restorers if pollen fertility of the hybrid was more than 80%. Partial maintainers were those with 6-30% pollen fertility

in the hybrid and partial restorers were IR50, effective restorers. We will use those with 31-79% pollen fertility. effective maintainer lines as male parents

Varieties Sinekeri 3, BG120 3,

in hybrid seed production next season. be effective maintainers for both CMS lines. Effective restorer lines will be used Hmawbi 2, and Kyawzeya were found to for backcrossing to develop new CMS

lines and Sintheingyi, Theedatyin, and

Identifying restorers and maintainers for cytoplasmic male sterile (CMS) lines lR58025 A and lR62829 A in Vietnam Pham Thi Mui and Bui Ba Bong, Cuu Long Delta Rice Research Institute, Omon, Cantho, Vietnam

We identified restorers and maintainers for promising CMS lines IR58025 A and IR62829 A in Cuu Long Delta of Vietnam. Improved lines and varieties adapted to Cuu Long Delta were crossed with IR58025 A or IR62829 A. F 1 hybrids were grown in the field during 1992 wet season and 1993 dry season. Hybrids and their male parents were transplanted in rows of 30 plants spaced at 20 × 20 cm.

To observe pollen sterility, florets from the upper part of the panicles were collected before flowering and pollen grains were stained with KI. Spikelet sterility was recorded on bagged panicles. When a hybrid showed 99-100% pollen sterility, its male parent was designated as a maintainer for the corresponding female parent (CMS line). When a hybrid showed more than 90% pollen and spikelet fertility, its male parent was identified as a restorer. Other male parents were considered to be partial restorers (see table). The frequency of maintainers for IR58025 A was higher than that for IR62829 A.

Most of the maintainers and restorers identified were adapted to Cuu Long Delta and are being used in a backcross program or to develop new F 1 hybrids.

Maintalner and restorer lines identified for CMS lines lR58025 A and lR62829 A in Cuu Long Delta, Vietnam, 1992 WS and 1993 DS.

lR58025 A lR62829 A

Maintainer Restorer Partial restorer Maintainer Restorer Partial restorer

OM43-26 OM59-7 OM576 MTL 58 MTL 61

lR50404 lR52280 lR19725

lR44595-70

OM53-71 IR72 lR44595-70 OM1037 OM987-1 OM80 OM547 OMCS6 lR42068 OMCS9 OM725 lR31917 lR35546 OM90-2 OM269 lR43158 lR35311 OM43-26

lR9729 OM987-1 IR64 IR64 16B OM547 lR42068 S818B

lR52287-15 lR42068 lR49517

Identifying and evaluating

male sterile (PGMS) lines in point (HP) of the range affects

Photoperiod sensitivity in fertility alteration of PGMS occurs only within a

photoperiod-sensitive genic specific temperature range. The higher

China multiplication of the sterile line. The

Ziguo Zhang, Hanial Zeng, and Jing Yang, Huazhong Agricultural University, Wuhan 430070, China occasionally exposed to low temperature

lower point (LP) affects sterility fluctuation of the PGMS line when

under long-day conditions. Both photoperiod and temperature We studied the percentages of fertile regulate fertility alteration of PGMS rice, pollen and spikelet fertility of PGMS including the original line Nongken 58 S. lines in China under different temperature


conditions during 1992 long-day and short-day seasons in Wuhan (30°30' N, 114° 04' E, 23 m altitude). Plants were grown in phytotrons for about 10 d, from the differentiation of stamen and pistil primordia stage to the meiotic division of pollen mother cell stage. We recorded percentage of fertile pollen during

heading and percentage fertility 30 d after heading of selfed-PGMS lines (Table 1).

Results show that HPs and LPs of PGMS lines are different. Lines can be divided into four groups based on combinations of HPs and LPs (Table 2).

The high HP-low LP group sterile lines (Nongken 58 S, 5088 S, 7001 S,

31111 S, and 1541 S) have stable sterilities under long-day conditions and can be easily multiplied under short-day conditions regardless of temperature changes. They can be used in the two-line hybrid production system for subtropical rice-growing areas.

Table 1. Fertility of PGMS lines under various conditions. Wuhan, China, 1992.

Fertility (%) Line Daylength a Fertility b

22°C 24°C 26°C 28°C 30°C 32°C

Nongken 58 S

5088 S

7001 S

31111 S

1541 S

Pei>ai 64 S

M901 S

HN5-2 S

8906 S

8902 S

8912 S

5047 S

Shuangguang S

9044 S

W6154 S

LD

SD

LD

SD

LD

SD

LD

SD

LD

LD

SD

LD

LD

SD

LD

SD

LD

SD

LD

LD

LD

SD

LD

LD

1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2

9.5 ± 15.6 0.3 ± 0.8

3.7 ± 5.6 0.5 ± 1.7

0.3 ± 1.5 0.0 ± 0.0

0.9 ± 0.4 0.0 ± 0.0

0.5 ± 1.5 0.0 ± 0.0 2.7 ± 4.1 0.0 ± 0.0

10.8 ± 25.4 0.0 ± 0.0 4.6 ± 8.8 1.3 ± 0.5

8.9 ± 9.2 4.5 ± 9.8

25.3 ± 17.2 17.3 ± 26.6

40.7 ± 19.2 15.73 16.0 ± 16.1 15.9 ± 23.6 31.5 ± 4.1 11.4 ± 13.4

19.9 ± 17.4 2.0 ± 2.8

17.2 ± 26.4 0.7 ± 1.6

2.3 ± 3.5 2.7 ± 9.9 0.2 ± 0.9 0.0 ± 0.0

47.3 ± 17.3 27.7 ± 15.2

0.2 ± 1.0 1.2 ± 2.0 0.0 ± 0.0 0.0 ± 0.0

18.5 ± 20.4 4.0 ± 5.4

0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0

17.7 ± 20.8 2.5 ± 4.6

0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0

26.1 ± 26.7

0.1 ± 0.5 0.0 ± 0.0 0.2 ± 0.2 0.0 ± 0.0

12.0 ± 14.5 8.2 ± 14.4 0.0 ± 0.0 0.0 ± 0.0

39.2 ± 32.6 0.0 ± 0.0

0.1 ± 0.9 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 2.3 ± 5.9 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

0.0 ± 0.0 0.1 ± 0.1 0.1 ± 0.1 0.3 ± 0.2

6.9 ± 9.8 1.9 ± 3.8

27.6 ± 25.9 35.4 ± 23.4 13.3 ± 12.2 18.4 ± 16.9

47.0 ± 22.1 15.5 ± 16.5 8.9 ± 14.5 0.0 ± 0.0

31.8 ± 26.8 18.9 ± 13.4 2.6 ± 2.7 0.0 ± 0.0

58.2 ± 3.8 48.5 ± 6.8 22.9 ± 9.9 17.5 ± 13.2

43.0 ± 18.9 37.4 ± 25.6

8.5 ± 14.8 1.4 ± 4.6 2.9 ± 2.7 2.4 ± 2.1

10.2 ± 20.0 17.1 ± 14.9 3.4 ± 7.8 3.8 ± 6.0

0.6 ± 2.0 0.0 ± 0.0

38.4 ± 24.6 24.1 ± 29.1 0.0 ± 0.0 0.0 ± 0.0 6.6 ± 10.6 1.7 ± 0.3 0.0 ± 0.0 0.0 ± 0.0 6.2 ± 16.9 2.8 ± 6.2 0.0 ± 0.0 0.0 ± 0.0

13.1 ± 21.0 1.1 ± 3.0 0.0 ± 0.0 0.0 ± 0.0 1.3 ± 0.9 0.0 ± 0.0 2.3 ± 10.6 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 2.1 ± 8.6 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 1.0 ± 1.0 0.2 ± 0.1 0.2 ± 0.4 0.0 ± 0.0 0.8 ± 3.2 0.0 ± 0.0 9.1 ± 13.2 4.6 ± 1.1

7.6 ± 7.2 0.0 ± 0.0 2.9 ± 1.1 1.1 ± 1.5

20.3 ± 23.1 9.6 ± 2.4 0.6 ± 1.9 0.0 ± 0.0 2.5 ± 6.0 0.5 ± 0.9

16.4 ± 17.7 7.4 ± 12.6

9.7 ± 17.9 1.8 ± 3.6

4.9 ± 13.6 0.0 ± 0.0

3.2 ± 5.6 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

1.7 ± 8.0 0.0 ± 0.0

5.8

16.2 ± 23.7 1.3 ± 2.5

2.2 ± 5.1 0.0 ± 0.0

0.9 ± 1.3 0.0 ± 0.0

4.8 ± 9.2 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

1.8 ± 4.3 0.0 ± 0.0

0.0 ± 0.0 0.0 ± 0.0

4.0 ± 2.5 1.5 ± 2.9

a LD = long-day season. Heading occurred 1-10 Aug 1992. SD = short-day season. Heading occurred 11-20 Sep 1992. b 1 =fertile pollen % ± S, 2 = spikelet fertility % ± S.


– –

–

Table 2. Temperature range of photoperiod sensitivity in fertility alteration in PGMS.

Line Low point (°C) High point (°C)

Nongken 58 S 24 30 5088 S 22 30 7001 S 22 28 31111 S 22 28 1541 S 22 (28) a

Pei>ai 64 S 22 (24) M901 S 24 (26)

8906 S 24 (26)

8902 S 28 30 8912 S 26 30 5047 S 26 (30) 9044 S 28 (32) Shuangguang S 28 32 W6154 S 28 (28)

a Numbers in parentheses were in other experiments.

HN5-2 S 24 (24)

The low HP-low LP group sterile lines (Pei'ai 64 S, M901 S, HN5-2 S, and 8906 S) have stable sterilities under long- day conditions (without impact of temperature) and under high temperature conditions (regardless of daylength). Their multiplications, however, are easily lost under short-day conditions when temperature rises occasionally. These PGMS lines can be used for producing hybrid seed in most rice-growing areas. Sterile lines can only be multiplied during certain seasons or at higher altitudes in tropical areas.

The high HP-high LP group sterile lines (8902 S, 8912 S, 5047 S, 9044 S, and Shuangguang S) can be multiplied easily under short-day conditions, but their sterilities are unstable under long- day conditions as temperature decreases. Because their sterilities are unstable, they are difficult to use in the two-line system. They can possibly be used in subtropical rice-growing areas of China.

The low HP-high LP group sterile lines (W6154 S and others) have stable sterilities under higher temperature without impact of photoperiod. Their sterilities, however, are unstable under long-day conditions when exposed to lower temperature. Their multiplication under short-day conditions can be affected when temperature rises occasionally. These lines can be used for hybrid seed production and multiplied during a specific season or at higher altitudes in tropical rice-growing areas. We do not recommend their use in the subtropics.

Inflorescence culture in rice (MS 2 ), 1.5 (MS 3 ), and 2 (MS 4 ) mg/liter

A. B. Mandal, P. Mohanraj, and A. K. Bandyopadhyay, Biotechnology Laboratory, Central Agricultural Research Institute (CARI), Port Blair 7441 01, India

We successfully induced calli and regenerated plants in salt-tolerant indica line IR3 1662-47-2-1 for exploitation of somaclonal variation. Young tillers were cut about 7-9 cm from the base of vigorous plants in pots. Tillers were thoroughly scrubbed with and dipped in 75% alcohol for 10 min. Leaf sheaths were stripped off under aseptic conditions.

Young inflorescences were divided into groups based on their length: DS 1 (0.5 cm), DS 2 (1 cm), DS 3 (2 cm), DS 4 (3 cm), DS 5 (4 cm), and DS 6 (5 cm). Inflorescences were cleaned with the commercial detergent Teepol (5% vol/ vol) for 5 min, rinsed in water, sterilized with 0.1 % aqueous HgCl 2 for 10 min, and then washed three times with sterile double-distilled water. Sterilized explants were placed on slant cultures with basal LS medium supplemented with 2,4-D and kinetin at rates of 0.5 (LS 1 ), 1 (LS 2 ), 1.5 (LS 3 ), and 2 (LS 4 ) mg/liter each, and on MS basal medium supplemented with naphthalene acetic acid and kinetin at rates of 0.5 (MS 1 ), 1

each. Cultures were kept in total darkness

at 25±2 °C. After 28 d, portions of calli were subcultured on the same medium without hormone. Remaining calli were directly placed on regeneration medium (LS basal + 2 mg kinetin/iter + 0.5 mg indole acetic acid/liter). For subculturing, culture tubes were kept in total darkness; for regeneration, cultures were maintained under 16:8 h 1ight:dark cycle. Light intensity was 2,000 lux.

LS 1 , MS 1 , MS 2 , MS 3 , and MS 4 failed to induce any calli, but direct plant regeneration without a visible callus stage was obtained in MS 2 , MS 3 , and MS 4 with 2-cm-long young inflorescences. LS 2 , LS 3 , and LS 4 induced callus formation. During peak callus formation, callus induction percentage and callus health varied significantly according to developmental stage of inflorescences (Table 1). Calli formed earliest in young inflorescences (0.5 and 1.0 cm), which grew vigorously and had high induction frequencies of healthy calli. Induction percentage was inversely proportional to developmental stage of the inflorescence. LS 3 was the best hormonal level for inducing calli.

In the subculturing experiment, all calli died within 16-22 d, suggesting

Table 1. Degree of callus-forming ability and callus health in lR31662-47-2-1.

Inflorescence length (cm)

Callus Peak callus- Callus induction forming period health Treatment

(%) (d) (1-6 scale) a

LS 2 0.5 1 2 3 4 5

LS 3 0.5 1 2 3 4 5

1 2 3 4 5

LS 4 0.5

82 78 70 68 50 44

100 100

90 84 62 52 90 86 82 74 60 47

12 - 15 12 - 15 16 - 18 16 - 19 25 - 26 40 - 42

2 1 3 3 5 6 1 1 2 4 6 6 1 1 4 5 3 3

a 1 = excellent, 2 - 3 =good, 4 - 5 = moderate, and 6 = poor.


- - - - - -

- - - - - -

Table 2. Regeneration ability of plants from hormones might be an integral developmental stage of the explant. inflorescence-derived calli of IR31662-47-2-1. component of media for successful Highest regeneration frequency occurred

Explant length (cm)

DS 1 (0.5) DS 2 (1) DS 3 (2) DS 4 (3) DS 5 (4) DS 6 (5)

Days to form Regeneration green plantlet (%)

23 74.2 20 65.0 26 40.6 25 25.2 23 22.8 21 19.0

subcultures. In the regeneration experiment, 2.4-D

was completely withdrawn and replaced with IAA. Appearance of green plantlets was fastest with 1-cm-long young inflorescences and slowest with 2-cm- long inflorescences. Regeneration frequency notably varied with

in 0.5-cm-long young inflorescences and lowest frequency in 5-cm-long inflorescences (Table 2).

Young inflorescences are a good source for rice tissue culture. They have efficient callus induction and redifferentiation frequencies.

perithecia produced varied greatly with

formation process of perithecium in fertile isolates with wide cross-fertility perithecial formation conformed with the combinations of isolates. In general, the continuous illumination. The process of

Evolution of rice blast (BI) fungus based on cross- fertility of Pyricularia grisea Sac. Chengyun Li, Yunnan Academy of Agricultural Sciences (YAAS), Kunming, China; Y. Fujita, Tropical Agricultural Research Center, Tsukuba, Japan; N. Hayashi, National Agricultural Research Center, Tsukuba; and Jiaru Li and Rui Shen, YAAS

We collected 500 monoconidial isolates of P. grisea from rice-growing regions of Yunnan Province, China. These isolates were crossed with standard isolates 57-R-33 (MAT1-1) and 57-R-28 (MAT1-2), both of which were isolated from Eleusine coracana (L.) Gaertn. Results showed that geographic environment and rice type influenced cross- fertility of P. grisea: in southern Yunnan, it was more than 60%, and in the high-altitude cold region where japonicas are grown, it was only 10%. Twenty-six isolates that produced perithecia and ascospores were selected for further study. (See table for location, hosts, mating type, perithecial formation by single culture of isolates, and rate of perfect state formation.)

with 16 isolates of MAT1-2. Although isolates crossed with the mating standard isolates produced ascospores, the cross-fertility of these isolates was remarkably different. Isolate YL 90-84 crossed with all fertile isolates. Y88-285 did not produce any ascospores in any cross combinations, although a few produced sterile perithecia. Number of

Ten isolates of MAT1-1 were crossed

also showed higher cross-fertility, producing more perithecia and ascospores compared with other isolates.

Isolates with greatest mating compe- tence, YL 90-84 (MAT1-2) and YL 90-7l, YL 90-90, YL 90-80, YL 90-77, and others (MAT1-1), were all isolated from upland rice in Xishuangbanna, southern Yunnan province. Single cultures of these isolates, except YL 90-84, produced sterile perithecia on oatmeal agar at 22 °C with

mating and also the perithecium-like structure produced by single cultures of Pyricularia from Eleusine indica (L.) Gaertn. and E. coracana (L.) Gaertn. The perithecia produced by single cultures had two common characteristics: they were derived from isolates with higher cross-fertility, and they formed two bands of perithecia. These isolates were all hermaphrodites. We speculate that Pyricularia might have evolved from

Location, host source, race, and mating type of Pyricularia grisea. Yunnan Province, China.

Isolate

YL 90-7 YL 90-10 YL 90-11 YL 90-13 YL 90-175 YL 90-51 YL 90-52 YL 90-84 YL 90-71 YL 90-74 YL 90-77 YL 90-80 YL 90-90 Y88-685 Y88-285 Y88-282 Y88-249 13-1 5-1 5-2 5-5 45-1 45-2 45-3 45-4 45-5

Location

Mojiang Mojiang Mojiang Mojiang Jingping Jingping Jingping Jinghong Jinghong Jinghong Jinghong Jinghong Jinghong Maguang Liuku Liuku Tengchong Tengchong Qujing Qujing Qujing Jinghong Jinghong Jinghong Jinghong Jinghong

Host source

Variety Type a

Dalixian 40 I Luoping ? Luoping ? Luoping ? Gaoshanzaogu ? Luopinggu ? Luoping ? Unknown U Unknown U Unknown U Unknown U Unknown U Unknown U

Yunjing 134 J Nuogu J 74-35 J 74-35 J Chujing 3 J Chujing 3 J Chujing 3 J Luexi U Luexi U Luexi U Luexi U Luexi U

D-you 63 I

Race

016-t 136 136 036 106 016 117 134-t 102 116 102 136-t 116

0 017 037-t

0 0

016-t 016-t 016-t 136 136 136 136 136

Mating

MAT1-2 MAT1-2 MAT1-2 MAT1-2 MATI-2 MAT1-2 MAT1-2 MAT1-2 MAT1-1 MAT1-1 MAT1-1 MAT1-1 MAT1-1 MAT1-2 MAT1-2 MAT1-2 MAT1-2 MAT1-2 MAT1-2 MAT1-2 MAT1-2 MAT1-1 MAT1-1 MAT1-1 MAT1-1 MAT1-1

P b R c

– 40.0 – 10.0 – 20.0 – 50.0 – 40.0 – 30.0 – 50.0 – 100.0 + 87.5 + 43.8 + 43.8 + 62.5 + 75.0 – 20.0 – 0.0 – 70.0 – 40.0 – 60.0 – 30.0 – 60.0 – 30.0 – 6.3 – 12.5 – 18.8 – 18.8 – 37.5

a I = indica, U = upland rice, J =japonica, ? = unknown. b P = perithecia production in single culture. + = produced, - = not produced. c R= rate of perfect state formation.


Pest resistance— diseases

homothallism to heterothallism and then to the infertile state in which the sexual function might have been lost.

of rice origin and has a long history of upland rice cultivation. The possibility that parasitic differentiation could be established from grasses to cultivated

Southern Yunnan Province is a center

rice (H. Kato’s hypotheses) might have occurred in this area. The Pyricularia in this area exhibit the same properties as those of grass isolates (E. indica, E. coracana). Many isolates produced a lot of perithecia and produced sterile perithecia in single culture (see table). The formation rate of Pyricularia

becomes gradually less from south to north—from temperate to cool to cold regions—until it cannot form. The trend from high to low fertility corresponds with direction of the spread of rice cultivation.

Reaction of some rice Reaction of rice breeding lines to blast (BI) in Guyana, 1991.

germplasm to leaf blast (BI) Breeding line score a reaction b Origin Breeding line score a reaction b Origin BI BI BI BI

in Guyana C. R. Paul, National Agricultural Research CT8008-3-5-5P-M 1 Institute, Mon Repos, East Coast

R ClAT

Guyana lR56446-94-3-1-2 1 R IRRI CT8008-3-5-7P-M 1 R ClAT Demerara; and J. S. Nanda, Guy/86/002,

lR56382-123-31 3 MR IRRI

Blast caused by Pyricularia grisea is an

NAR8 F 5 -1-3-2 3 MR Guyana CT8008-3-5-8P-M 1 R ClAT

CT8238-6-14-P-M 1 R ClAT NAR9 F 5 -1-3-2 5 MS Guyana

important rice disease in Guyana. We screened 377 breeding lines for leaf B1 Diwani 3 MR NAR126 F 4 -2-5-2 5 MS Guyana resistance during Aug and Sep 1991 . Surinam NAR151 F 4 -4-3 5 MS Guyana

Breeding lines were grown in Interna- Eloni 3 MR NAR210-1-1-4 1 R Guyana Surinam NAR210-1-4 1 R Guyana

tional Rice Blast Nurseries to score leaf lR8192-31-2-1-2 3 MR IRRI NAR218-2-4-4 3 M R Guyana

CT80083-5-2P-M 1 R ClAT lR54791-19-2-3 1 R IRRI

CT8008-3-5-6P-M 1 R ClAT lR56383-46-1-2-1 3 MR IRRI

CT8222-4-1-8P-M 1 R ClAT

NAR126 F 4 -2-1-1 3 MR Guyana CT8285-13-5-2P-M 1 R ClAT NAR12 F 2 -1-2-3 5 MS Guyana CT8285-13-1-3P-M 1 R ClAT

NAR8 F 5 -2-3-1 3 MR Guyana

B1 reactions. Highly B1-susceptible variety Rustic was used as susceptible check and in spreader rows. Varieties Diwani and 6039 served as resistant checks.

Entries were inoculated at the four- leaf stage with chopped infected leaves. Nursery beds were irrigated twice a day between 1000 and 1100 h, and 1500 and 1600 h. Beds were covered with polyethylene sheets at night to maintain high humidity.

Resistance to whitebacked planthopper (Sogatella furcifera) in rice varieties with different genes for brown planthopper (BPH) resistance R. Velusamy, M. Ganeshkumar, Y. S. Johnson Thangaraj Edward, and M. Gopalan, Tamil Nadu Agricultural University, Coimbatore, lndia

We evaluated 15 BPH-resistant rice varieties for resistance to S. furcifera using the standard seedbox screening test

lR44624-127-1-2-2-3 3 MR IRRI lR47761-27-1-36 1 R IRRI lR51678-93-2-2 5 MS IRRI lR52350-93-2-2 3 MR IRRI lR53306-36-1-3-1 1 R IRRI lR53306-64-1-3-2 3 MR IRRI IR53649-AC5-2 1 R IRRI

Pedigree 9 3 M R Guyana Pedigree 12 3 TX06

MR Guyana 5 MS USA

TX49 (Aromatic 3 MR USA

6039 Lemont)

3 MR Guyana

a Scored (0-9) using the Standard evaluation system for rice. b R = resistant, MR = moderately resistant, and MS = moderately susceptible.

Entries were scored on a scale of 0-9

(see table). scored 7-9. Sixteen lines were resistant, conducive to severe disease development rice when the susceptible check had moderately susceptible under conditions using the Standard evaluation system for 16 lines moderately resistant, and 6 lines

Resistance of BPH-resistant rice varieties to S. furcifera in the standard seedbox screening test (SSST) and modified seedbox screening test (MSST). a

Plant damage rating b

Variety Genes for resistance to BPH SSST MSST

lR47-B2-6 Bph1 9.0 a 9.0 a Mudgo Ptb18

Bph1 1.8 bc 1.0 a bph2 9.0 a 1.0 b

Rathu Heenati Bph3 1.0 c 1.0 b Gambada Samba bph4 1.0 c 1.0 b Babawee bph4 1.4 bc 1.0 b ARC10550 bph5 1.8 bc 1.0 b Swarnalata bph6 1.4 bc Ptb21

1.0 b

Ptb33 1.0 c 1.0 b

IR26 1.4 bc 1.0 b

IR36 IR56

9.0 a 1.0 b

IR62 9.0 a 1.0 b

IR64 1.0 b

TN1 1.4 bc 1.0 b

bph2 + Bph3 bph2 + Bph3

Bph1 9.0 a bph2 Bph3 Bph3 2.2 b Bph1

9.0 a

No gene 9.0 a 9.0 a (SSST) and modified seedbox screening a ln a column, means followed by the same letter are not significantly different at 5% level by DMRT; av of 5 replications. test (MSST). The experiment was laid out b Damage was rated on a 0-9 scale where 0-3 = resistant, 4-6 = moderately resistant, and 7-9 = susceptible.


Pest resistance — insects

in a split-plot design with screening methods as the main plot and varieties as subplots. Treatments were replicated five times.

In the SSST, seeds of BPH-resistant varieties and susceptible check TN1 were sown in rows in seedboxes (60 x 40 x 10 cm). At 7 d after sowing (DAS), seedlings were thinned to 15/row and infested with eight 2d-instar S. furcifera nymphs/plant. When all TN1 seedlings were dead, plants were rated for damage on a 0-9 scale where 0-3 = resistant, 4-6 = moderately

resistant, and 7-9 = susceptible. In the MSST, seeds were sown and

seedlings thinned as described for the SSST experiment. Plants were infested with four 2d-instar nymphs/plant at 20 DAS. Damage was rated at 25 d after infestation when TN1 was dead.

In the SSST, insects in the initial infestation killed TN1; in the MSST, the progeny of the infesting insects killed TN1.

There were distinct differences among BPH-resistant varieties in both tests (see

table). Mudgo and IR64 ( Bph 1 gene), Rathu Heenati and IR62 ( Bph 3 gene), Gambada Samba and Babawee (bph 4 gene), ARC10550 (bph 5 gene), Swarnalata ( bph 6 gene), and Ptb21 and Ptb33 ( bph 2 + Bph 3 genes) were rated as resistant in both tests. Varieties Ptbl8 and IR36 ( bph 2 gene) and IR56 ( Bph 3 gene) were susceptible in the SSST as seedlings, but were highly resistant as the older plants in MSST (see table).

Field screening of rice cultivars for resistance to leaffolder (LF) ( Cnaphalocrocis medinalis Guenée) and stem borer (SB) ( Sesamia inferens Walker) S. Ray, M. Singh, and G. Singh, Indian Council for Agricultural Research Complex for Northeastern Hill (NEH) Region, Sikkim Centre, Tadong, Gangtok 737102, India

LF and SB can be destructive rice pests in Sikkim. Infestations of LF and SB occur from late Aug through Oct. We observed peak infestation of LF at panicle initiation, the last week of Sep. Yield losses to both pests can be avoided by using resistant varieties.

Twenty-four cultivars with medium to late maturity from around India, including the NEH Region, were transplanted in 2-m 2 field plots during 1990 and 1991

kharif (monsoon) seasons with three replicates. All recommended crop management practices were followed except plant protection measures. For each entry, we recorded number of hills with LF and SB infestations at panicle initiation and total hills per plot.

Sikre, Khonorullo, Khusaro, RCPL 3-5, and Dhanse were found moderately resistant to LF, 13 cultivars were moderately susceptible, and 6 cultivars were susceptible. Sikre, Srinivasa, IRAT141, Sarassa, and RCPL3-4 were moderately resistant to SB, 15 cultivars were moderately susceptible, and 4 cultivars were susceptible (see table).

Screening of rice cultivars for resistance to LF and SB. Sikkim, India, 1990 and 1991 kharif seasons.

LF incidence SB incidence (% infested hills/plot) (% infested hills/plot)

Cultivar 1990 1991 Mean Reaction a

1990 1991 Mean Reaction

VL 23 23.1 8.3 15.7 S 6.4 3.3 4.9 MS Nagoba 8.6 9.5 9.0 MS 2.5 2.2 2.4 MS Sikre 0.0 4.5 2.3 MR 0.0 0.7 0.4 MR Srinivasa 7.3 10.6 8.9 MS 0.0 3.6 1.8 MR Zhapara 7.0 10.8 8.9 MS 1.2 4.2 3.3 MS DR92 11.3 13.6 12.5 S 2.6 12.8 7.7 MS Khonorullo 0.0 3.1 1.5 MR 7.4 1.6 4.5 MS TRUA 490 0.0 11.2 5.5 MS 14.1 2.1 8.1 S IC25697 5.9 2.2 4.1 MS 10.3 7.8 9.0 S Khusaro 2.0 0.8 1.4 MR 0.0 4.4 2.2 MS PP2-24-1557 12.3 5.5 8.9 MS 7.0 1.3 4.2 MS RCPL 3-5 3.2 5.5 4.3 MR 9.5 2.0 5.8 MS IRAT141 8.0 8.2 8.1 MS 2.3 0.7 1.5 MR IR36 10.0 5.7 7.9 MS 12.9 14.9 13.9 S Sarassa 11.3 6.9 9.1 MS 0.0 0.7 0.4 MR Jaya 16.7 13.3 14.8 S 2.9 9.9 6.4 MS ICPL 131 4.1 7.6 5.8 MS 3.1 1.5 2.3 MS Akhanpan 11.1 6.3 8.7 MS 17.5 11.5 14.5 S ARU3 13.3 7.8 10.6 S 1.1 6.6 3.8 MS CSR80 17.1 7.8 12.5 S 2.3 3.5 2.9 MS Attey 4.8 8.2 7.0 MS 1.2 3.4 2.3 MS Vikash 10.9 4.5 7.7 MS 4.4 3.5 3.9 MS

Dhanse 0.0 3.7 1.9 MR 7.2 6.8 7.0 MS RCPL 3-4 9.9 9.1 9.5 S 0.0 0.7 0.4 MR

a MR = moderately resistant, MS = moderately susceptible, and S = susceptible.

Evaluation of rice genotypes for resistance to orange- headed leafhopper (OHLH) in the Hill Zone of Karnataka, India V. V. Belavadi, B. Mallik, A. Manjunath, and Y. G. Shadakshari, Regional Research Station (RRS), Mudigere 577132, India

Orange-headed leafhopper ( Thaia subrufa M., Cicadellidae: Homoptera) is a serious pest of summer rice in the Hill Zone of Karnataka. Feeding by nymphs and adults causes leaves to become speckled. The speckles coalesce when infestation is severe, leading to hopperburn symptoms. Grain losses can range from 30 to 70%.

Rice genotypes were screened for resistance to OHLH in two phases at RRS. We mass-screened 243 varieties in phase one (1986-88). Each entry was planted in three rows with two replica-


Evaluation of rice varieties for resistance to OHLH. RRS, Mudigere, India.

OHLH Entry Yield (t/ha)

Damage score a Nymphs/leaf b (no.)

IET10131 1.2 4.7 4.4 IET10396 1.3 12.2 4.3 CTH1 4.2 26.0 4.2 IET10117 1.7 7.0 4.1 RR32 3.0 27.0 4.0 IET6983 2.7 14.0 4.0 Rasi 5.2 43.0 4.0 Madhu 5.0 33.0 3.9 Tibetan Sanna 1.3 14.0 3.2 IR20 4.4 37.0 3.2 Mangala 3.7 32.0 3.3

(susceptible check)

a Highest score recorded in 2 yr on a 0-6 scale. b Mean of 45 leaves.

tions. We scored damage from OHLH on 2 = 11-20%, 3 = 21-30%, 4 = 31-40%, the 2d leaf from the top on a 0-4 scale damage, 1 = <l0% leaf area damage,

counting nymphs, which were recorded susceptible (3.1-4). 15 leaves in each plot for scoring and (0-1), susceptible (1.1-3), and highly population. We randomly selected were classified as moderately resistant top of each entry to assess OHLH 51-75%, 4 = more than 75%. Varieties counted nymphs on the 3d leaf from the leaf area damage, 2 = 26-50%, 3 = 5 = 41-50%, and 6 = >51 %. We also where 0 = no damage, 1 = less than 25%

varieties were screened intensively during In mass screening, 9.8% of entries 1989-90 and 1990-91 summers in a were moderately resistant to OHLH, randomized block design with three 81.5% susceptible, and 8.6% highly replications in 6-m2 plots. Mangala was susceptible. Damage scores in phase the susceptible check. Damage was two ranged from 1.2 in IET10131 to scored on a 0-6 scale where 0 = no 5.2 in Rasi, IET10131 yielded more

In phase two, 10 moderately resistant 30 d after transplanting.

Resistance of rice varieties to OHLH damage based on damage score and nymphs/leaf. RRS, Mudigere, India.

grain than other varieties (see table). When OHLH nymph populations were

plotted against damage scores, IET10131, IET6983, IET10396, IETl0l17, and Tibetan Sanna emerged as resistant, while Madhu, CTH 1,1R20, and Rasi proved susceptible (see figure).

Resistance to gall midge (GM) Orseolia oryzae in Chinese rice varieties compared with varieties from other countries Tan Yujuan, Pan Ying, and Zhang Yang, Plant Protection Institute, Guangdong Academy of Agricultural Sciences, (GAAS), and Zhao Lixia and Xu Yenkang, Rice Research Institute, GAAS, China

China was reported to have four GM biotypes in 1983. Chinese GM biotype IV could damage six GM-resistant varieties from other countries that carried different GM resistance genes. Daqiuqi and other Chinese traditional varieties resist all Chinese GM biotypes.

We have bred three photoperiod- sensitive, GM-resistant varieties. Kangwen 1, Kangwen 2, and Duokang 1, respectively, have growth durations of

Table 1. Reactions of GM-resistant varieties to 2 GM biotypes. GAAS, China.

Growth Variety stage

Biotype 1 a Biotype IV b

Origin Samples Plants Samples Plants

(no.) infested (no.) infested (%) (%)

Seedling c Kangwen 2 GAAS 79 0.0 44 2.3 Dekang 1 GAAS 61 0.0 57 0.0 Kangwen 1 GAAS 87 0.0 44 81.8 Daqiuqi GAAS 67 1.5 Yangshanzhan d GAAS 117 0.6 Leuang 152 IRGMN e 86 0.0 38 63.2 OB677 IET2911 W1263 Muey Nahng 62M Ptb21 TN1 (susceptible check)

Tillering f Duokang 1 Kangwen 2 Kangwen 1 TN1 (susceptible check)

IRGMN IRGMN IRGMN IRGMN IRGMN IRGMN

GAAS GAAS GAAS GAAS

80 80 60 48 92 51

327 381 332 343

0.0 0.0 5.0

91.7 93.5 92.2

0.0 0.0 0.0

72.6

39 46 43 40 49 38

889 950

1039

84.6 47.8 16.3 60.0

100.0 92.1

0.0 16.8 14.7

a Insects were collected from Huaxian. b Insects were collected from Yangshan; data were recorded in Yangshan fields; infested by natural GM biotype IV population. c Infested on a hill basis. d Resistant donor of Kangwen 1. e lRGMN = International Rice Gall Midge Nursery (Thailand); f Infested on a tiller basis.


– –

– – – –

Table 2. GM-resistant reactions of Daqiuqi and its hybrid progeny. a GAAS, China.

Test item Parent and Resistant Susceptible Resistant: hybridized combination plants (no.) plants (no.) susceptible

Resistance Wanhuaai 1 of parent TN1 (susceptible check)

W1263 Daqiuqi

Resistance Wanhuaai 1/ heredity Daqiuqi

Wanhuaai 1/ Daqiuqi//Wanhuaai 1

Allelic W1263/ relationship Daqiuqi

W1263/Daqiuqi// Wanhuaai

0 0

73 74

F 1 30

F 2 313

B 1 F 1 40

F 1 97 F 2 442 T 1 66

70 80

2 0

0

104 3:1 0.008

47 1:1 0.563

7 60 15:1 27.857 19 3:1 0.317

a P = 0.05, c2 = 3.84.

132, 130, and 130 d; are 90, 83, and 93 cm resistant in regions where only GM tall; and yield 5.9, 7.0, and 6.6 t/ha in different GM biotypes. Kangwen 1 was

and kept in nylon cages with three which represent different ecosystems with varieties were infested with GM adults or highly resistant to GM at all 22 sites, house and field. Seedlings and tillers of Kangwen 2 and Duokang 1 were resistant IRRI screening method in the green- Fujian, Jiangxi, and Hunan Provinces. Chinese GM biotypes I and IV using the GM outbreaks in Guangzhou, Guangxi,

Resistance was evaluated with planted at 22 sites experiencing serious biotypes I and II occurred. Guangzhou. Since 1989, they have been

replications. Resistance was evaluated as average of silvershoot frequency based on a random sample.

differed distinctly (Table 1), but reactions to GM at seedling and tillering stages were similar. All varieties except Muey Nahng 62M and Ptb21 were resistant to Chinese GM biotype I. Only Kangwen 2 and Duokang 1 were resistant to Chinese GM biotype IV.

We analyzed the inheritance and allelic relationship of resistance to GM in varieties Wanhuaai 1 and Daqiuqi, and cross W1263/Daqiuqi. Parents and F 1 , F 2 , B 1 F 1 , and T1 progeny were infested at seedling stage with Chinese GM biotype I. Silvershoots and healthy plants were recorded per hill.

Results indicate that Daqiuqi, the resistant parent of Kangwen 2 and Duokang 1, has a single dominant gene for GM resistance (Table 2). This gene is nonallelic to gene Gm-1 of W1263. We think that the resistance gene of Daqiuqi is also not allelic to gene Gm-2 of Leuang 152. Further study is needed.

Reactions of varieties to GM biotypes

Resistance to green leafhopper (GLH) in hybrid rice R. Velusamy, Entomology Department; P. Jayamani, K. Thiygarajan, and M. Rangasamy, School of Genetics, Tamil Nadu Agricultural University, Coimbatore 641 003, India

We evaluated three hybrids and their parents for resistance to GLH Nephotettix virescens (Distant). Seeds of test lines

Reaction of hybrids and their parents to GLH.

Designation Damage rating a

lR62829 A/IR1019866-2 R 1 c lR58025 A/IR10198-66-2 R 1 c lR62829 A/Pusa 150 R 1 c lR62829 A 3 b lR58025 A 9 a

Pusa 150 R 1 c Ptb33 1 c TN1 9 a

a Mean of 5 replications. Means followed by a common letter are not significantly different at the 5% level by DMRT.

lR10198-66-2 R 1 c

were sown in 40-cm rows 2-3 cm apart in wooden trays (60 × 45 × 10 cm) in a greenhouse. Ptb33 served as resistant check and TN1 as susceptible check. The experiment was arranged in a randomized complete block design; each breeding line was replicated five times. Seedlings were thinned to 15 per row at 7 days after sowing and infested with 5-6 2d-instar

Screening rice accessions for resistance to thrips R. Rajendran. M. M. Zainudeen, N. Raju, and K. Chozhan, Tamil Nadu Rice Research Institute (TRRI), Aduthurai, lndia

We screened 177 rice accessions from the All India Crop Improvement Project for resistance to thrips Stenchaetothrips biformis (Bagnall) in the field at TRRI during Aug 1991 and 1992. Each test entry was planted in a 4-m-long row at 20- × 15-cm spacing. One row of susceptible check TN1 was planted for every 10 rows of test entries, with two replications. Damage was evaluated by

nymphs per seedling. Plant damage was scored on a 0-9 scale when the susceptible check scored 9.

IR58025 A/IR10198-66-2 R, and IR62829 A/Pusa 150 R and restorer lines IR10198-66-2 R and Pusa 150 R exhib- ited high levels of resistance to N. virescens (see table).

Hybrids IR62829 A/IR10198-66-2 R,

counting total leaves and damaged leaves in randomly selected plants at 25 d after planting. Mean infestation percentage was calculated and damage scored as 0-10% infestation = resistant (R), 11-20% = moderately resistant (MR), 21-50% moderately susceptible (MS), and 51-100% = susceptible (S).

Accessions BPT6038, BPT688 1, BPT7325, KAU42-40-4-1, MTU11351, RP2333-59-25, RP2543-12874-286-1, and RP1746-12360-340 were resistant. Nine accessions were moderately resistant (see table).


– –

– –

– – – –

c 2

Evaluation of rice varieties for lowland cultivation in Papua New Guinea M. S. Sajjad, Agriculture and Livestock Department, Food Management Branch, Erap Research and Development Centre, P.O. Box 1984, Lae, Papua New Guinea

We evaluated introduced varieties BR12- 5-5-1-1, IR19728-2-2-2-2, IR13429-196- 1-20, IR46, IR54, IR4744-295-2-3, and local varieties Wantok, Tambu, and Senis under lowland field condition at Bubia during 199 1.

We transplanted 20-d-old seedlings at 2 seedlings/hill, at a plant-to-row distance of 20 cm. The experiment was laid out in a randomized complete block design with four replications. Fertilizer was applied at 120-60-60 kg NPK/ha. All P and K and 50% N were applied basally. The remaining N was topdressed in two equal splits 20 and 40 d after transplanting. Normal cultural practices were followed during the growing period of crop.

Data on yield were recorded after harvesting a 15-m 2 area/variety per rep1ication. Data on yield components were recorded for 20 plants that had no missing hills around them/variety per replication.

Varieties Wantok, Tambu, IR13429- 196-1-20, IR46, IR54, IR4744-295-2-3, and BR12-5-5-1-1 yielded more than the others (see table). These varieties also had superior yield components, including grains per panicle, percent panicle fertility, and l,000-grain weight.

Reaction of rice accessions to thrips at TRRI, Aduthurai, India. Aug 1991 and 1992.

Infestation (%)

1991 1992 Accession Cross parents Reaction a

BPT6038 BPT6881 BPT7325

MTU11351 KAU42-40-4-1

RP2333-59-25 RP2543-12874-286-1 RP1746-12360-340 RP2548-1702-5 CR157-212 VRS100001 OR443-80-7 OR776-SSD-47 RB02-111* R650-1817 RNR52147

BPT6090 BPT6093 BPT6884 TNAU LFR842718 KAU8754 KAU8755 KAU8759 KAU8770 TN1 (check)

RP2333-315-16

BPT3291/ARC6650 MTU5182/IR50 MTU4870/IR50 MO 6/Pokkali 372

Ratna/ARC10659 Rasi/RP1579-38 RPA5854/RP79-9//Rasi/PTB12 ARC5723/ARC665O/ARC7328 Vijaya/PTB21 CNA 762260

Daya/lR36 Samaridhi/lR8608-298

IR8/Siam 29//IR8/PTB21 Ratna/ARC10659 BPT2685/ARC5984 BPT2685/ARC5984 MTU5182/IR50 Bhavani/ARC10550 IR36/Jyothi IR36/Pavizham IR36/Annapoorna BR51/23332 DGNG/Tsai-Yuan/Chan

lR19660-73-4/IR1416-131-5

IR36/OR 127-1

CR157-392/OR 57-21

4.2 5.0 5.8 7.0 6.9 9.0 5.3 7.0 7.6 8.2 9.3 9.0 9.8 9.0 9.9 10.0

10.2 10.5 10.5 10.7 11.1 15.0 12.0 12.0 12.1 17.0 13.0 17.0 15.3 16.0 15.8 19.0 16.3 15.0 23.70 25.0 28.30 27.0 28.5 29.0 28.6 25.0 29.0 27.0 31.0 32.2 33.7 34.5 38.9 37.0 89.9 90.0

R R R R R R R R

MR MR MR MR MR MR MR MR MR MS MS MS MS MS MS MS MS S

a R = resistant (0-10% infestation), MR = moderately resistant (11.20%). MS = moderately susceptible (21-50%), and S = susceptible (51-100%).

Performance of rice varieties under lowland field condition. a Bubia, Papua New Guinea, 1991.

Yield Plant productive panicle Grains/ Panicle 1,000-

(cm) hill (no.) (cm) (no.) (%) (g) Variety (t/ha) height tillers/ length panicle fertility grain wt

Wantok 8.9 a 109.1 a 17.0 a 26.8 b 177.3 a 90.0 a 26.6 a Tambu 8.8 a 102.2 b 18.0 a 27.6 a 159.0 a 91.0 a 25.2 b Senis 6.1 b 91.7 c 14.1 b 25.5 a 119.5 d 89.0 a 26.6 a lR19728-2-2-2-2 4.9 c 83.2 d 12.1 b 25.2 a 109.3 d 85.0 b 20.0 c lR13429-196-1-20 8.9 a 103.3 b 17.4 a 27.9 a 148.5 b 89.5 a 21.1 c

8.3 a 105.0 a 16.1 a 25.0 a 118.6 d 91.0 a 25.3 b IR54 IR46

lR4744-295-2-3 9.3 a 104.4 a 21.8 a 26.4 a 112.0 d 88.2 a 25.1 b

7.9 a 108.6 a 17.4 a 23.6 a 126.3 c 90.2 a 21.3 c

BR12-55-1-1 8.4 a 102.7 b 20.0 a 24.0 a 135.1 c 87.5 a 20.0 c

a ln a column, figures followed by a common letter are not significantly different at the 5% level by DMRT.


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Two newly developed glutinous rice varieties for Assam, India

Table 2. Grain yield of Kmj 3-292 and Kmj 3-296-3 in various locations, Assam, India.

Yield (t/ha) Location Year

Kmj 3-292 Kmj 3-296-3 Local glutinous T. Ahmed, G. R. Das, and A. K. Pathak, Regional Agricultural Research Station (RARS), Assam Agricultural University, Titabar RARS, Titabar 785630, India

RARS, Titabar 1985 4.0 3.5 2.6 RARS, Titabar 1988 5.4 3.4 2.8

1989 3.8 3.4 2.6

We developed high-yielding glutinous rice varieties Kmj 3-292 (Bhogali) and Kmj 3-296-3 (Rongili) from a cross between Ghew Bora, a traditional tall, glutinous rice, and Kmj 1-52-2, a locally developed semidwarf nonglutinous rice. Kmj 3-292 and Kmj 3-296-3 have been recommended for planting in sali (winter) season in Assam under flood-free, medium to shallow water condition.

Glutinous rices grown in Assam are generally tall, traditional, photoperiod- sensitive varieties with very low yield. Farmers accepted Kmj 3-292 and Kmj 3-296-3 because of their high yield and grain quality. (See Table 1 for important characteristics of these varieties.)

Kmj 3-292 is a semidwarf with an average height of about 100 cm. Kmj 3-296-3 is a tall (150 cm), stiff-strawed variety. Both were tested at different locations during sali season (Table 2). Average duration to 50% flowering was 129 d for Kmj 3-292 and 133 d for Kmj 3-296-3. Although mid-Jul is the best time for transplanting, these varieties can be planted until Aug (using 60-d-old seedlings) with little effect on normal yield.

Stickiness and acceptable taste are the important characters of glutinous rice in Assam. These high-yielding varieties are compatible with local glutinous rice varieties for stickiness, taste, and cooking time.

Table 1. Important characteristics of Kmj 3-292 and Kmj 3-296-3. Assam, India.

Character Kmj 3-292 Kmj 3-296-3

Panicle length (cm) Grain length (mm) L:B of grain Kernel length (mm) L:B of kernel 1,000-grain wt (g) Husk color Kernel color Endosperm type Abdominal white

24.2 9.7 4.3 6.8 3.50

25.0 Pigmented

White Glutinous Opaque

27.5 8.4 3.1 6.1 2.62

24.8 Straw White

Glutinous Opaque

All India Rice Improvement Project Chiplima 1991 4.6 6.0 Cuttack 1991 5.7 5.1 Karimganj 1991 3.0 3.6 Raipur 1991 2.2 2.9

Farms (av of 5 locations) 1989 3.3 3.6 2.5

Yield performance of rice hybrids in Cuu Long Delta, Vietnam

variety OM90-9 was used as a check.

6.6 t/ha (Table 1). Low yields of some Yields of hybrids ranged from 1.7 to

hybrids were due to high spikelet sterility

Van Luat, Cuu Long Delta Rice Research Institute (CLRRI), Omon, Cantho, Vietnam planthopper. Hybrid IR62829 A/

Nguyen Anh Tuan, Bui Ba Bong, and Nguyen and hopperburn, caused by brown

IR47310-94-4-3-1 R was ranked first at We evaluated 20 IRRI rice hybrids developed from cytoplasmic male sterile (CMS) lines IR58025 A and IR62829 A at three irrigated locations in Cuu Long Delta. Uniform trials using a randomized block design with three replications were conducted in 1993 dry season. Single seedlings were transplanted at 20- × 20- cm spacing in 8-m 2 plots. Fertilizer rate was 100-40-30 kg NPK/ha. High-yielding

two locations and first on average among hybrids studied. It matured in 105 d, 1 wk earlier than the check (Table 2).

significant yield advantage over the check, a few promising hybrids, including IR62829 A/IR47310-94-4-3-1 R,

IR58025 A/IR32358-90-3-3 R, will be evaluated further.

Although none of the hybrids showed

IR58025 A/IR54742-22-19-3 R, and

Table 1. Yield (t/ha) of rice hybrids at 3 locations in Cuu Long Delta, 1993 DS.

Location Hybrid

Omon Tanhiep Binhduc

lR62829 A/lR47310-94-4-3-1 R 5.8 7.3 6.8 OM909 (check) 5.3 6.5 7.4

lR58025 A/lR32358-90-3-3 R 4.8 5.7 6.7 lR58025 A/lR54742-22-19-3 R 4.9 5.3 7.5

lR62829 A/lR29723-143-3-2-1 R 5.7 5.0 5.8 lR62829 A/lR54742-22-19-3 R 4.5 5.0 6.5 lR58025 A/lR35366-28-3-1-32-2-2 R 4.1 5.5 6.2 lR58025 A/IR21567-18-3 R 4.7 4.5 6.4 lR58025 A/34686-179-12-1 R 3.9 4.5 6.5 lR58025 A/IR19058-107-1 R 3.8 4.9 5.4 lR58025 A/IR72 R 3.0 5.3 4.9 lR62829 A/lR32809-26-3-3 R 3.1 4.7 4.7 lR62829 A/lR44675-101-33-2-2 R 3.2 4.0 5.0 lR58025 A/lR32809-26-3-3 R 3.1 5.3 3.2 lR62829 A/lR40750-82-2-3 R 3.4 5.1 2.9 lR62829 A/lR28238109-1-3-2-2 R 2.8 4.9 2.7 lR58025 A/lR52256-5-2-2-1 R 2.1 3.6 3.8 lR58025 A/lR35454-18-1-2-2-2 R 1.4 3.3 4.3 lR58025 A/40750-82-2-2-3 R 1.3 3.4 3.8 lR62829 A/IR37839-101-1-1-1 R 1.5 1.8 3.5 lR58025 A/lR29723-143-3-2-1 R 0.4 1.8 2.9

LSD (0.05) 1.0 0.7 0.9

Av

6.6 6.4 5.9 5.8 5.5 5.4 5.3 5.2 5.0 4.7 4.4 4.2 4.1 3.9 3.8 3.5 3.2 3.0 2.8 2.3 1.7


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Performance of SBR80-643-14-1-1 in uniform variety trials, Bihar, India, 1985-89.

Year Entry Yield (t/ha)

Sabour Tiloundha Patna Pusa Av

1985 SBR80-643-14-1-1 2.4 2.6 3.0 2.1 2.6 BR9 Sugandha

LSD 450 CV (%) 15.8 11.7 25.6 16.1

1986 SBR80-643-14-1-1 2.0 3.3 2.6 2.6 BR9 Sugandha

LSD CV (%) 13.9 14.5

1987 SBR80-643-14-1-1 2.9 3.4 3.1 BR9 Sugandha 2.6

LSD CV (%) 9.4 12.6

1988 SBR80-643-14-1-1 BR9 Sugandha 2.6

CV (%) 11.6 15.6 LSD 470 380

1989 SBR80-643-14-1-1 2.7 2.4 2.7 BR9 Sugandha

LSD CV (%) 10.2 12.1

1.3 2.4 2.0 1.5 1.9 1.5

1.3 3.3 1.9 2.1 1.1

323 350

412

2.8 1.9

1.9 1.9 2.2

354

402 3.4 2.0

706

2.8 2.5 2.1

2.5 460

4.2 3.5 2.6 2.2 4.0 3.3

2.3 218

2.2 591

2.5

2.2

Performance of IRRI rice hybrids at Rice Research Institute (RRI), Kala Shah Kaku, Lahore, Pakistan S. S. Ali, S. J. H. Jafri, and M. Anwar Butt, RRI, Kala Shah Kaku, Lahore, Pakistan

Twenty-one hybrids using CMS lines IR58025 A and IR62829 A were evaluated at RRI with local checks KS282 and IR6. The experiment was laid out in a randomized complete block design with three replications conducted during 1992 kharif (monsoon) season. We transplanted 35-d-old seedlings on 15 Jul 92. Net plot size was 2 × 6.25 m 2 with a plant-to-plant distance of 23 cm. Ferti- lizer was applied at 100-50-0 kg NPK/ha. Recommended plant protection measures were adopted. We randomly selected 15

Xiang-Zao Xian No. 15: a high-quality variety in Hunan, China Yu Yinghong, Liu Jingmin, and Huang Jinxia, Hunan Rice Research Institute, Hunan 410125, China

Semidwarf 86-70 (selected from IR19274- 26-2-3-1-2) is a long-grained, high-quality, high-yielding variety with multiple pest resistances and wide adaptability. 86-70 was released as Xiang-Zao Xian No. 15 in Hunan Province in March 1993.

The variety has an average growth duration of about 118 d. Xiang-Zao Xian No. 15 performed well in 1990-91 regional trials in early rice areas. Average grain yield was 6.4 t/ha.

Xiang-Zao Xian No. 15 has grain length of 7.5 mm, 3.8 L-W ratio, 1.8% average chalkiness score, high translucency, 69 mm gel consistency, alkali spreading value of 7, 19.6% average amylose content, and 9.3% protein content. Cooked grain is soft and tastes good.

Hunan soft rice is the trade name of Xiang-Zao Xian No. 15. This variety won the Golden Prize at the First Agricultural Product Exhibition of China in Oct 1992. Xiang-Zao Xian No. 15 was grown on 30,000-40,000 ha in Hunan Province in 1992 and is spreading quickly in Hubei, Jiangxi, Zhejiang, and Fujian provinces.

Kamini: a quality rice released in Bihar, India R. Thakur, Plant Breeding Department, Rajendra Agricultural University, Pusa, Samastipur 848125, India; and M. A. Hassan, A. K. Roy, and N. C. Ghose, BAC, Sabour, Bhagalpur, India

In areas of Bihar, Uttar Pradesh, and West Bengal, high-quality scented rice varieties are cultivated for use in specialty foods. Their price is at least 2-3 times more than that of ordinary varieties.

There are many tall, photoperiod- sensitive, high-quality scented varieties grown around the region. They have short, fine grains and excellent cooking quality. Popular variety Sugandha, released in the 1980s, has become highly susceptible to blast (B1) and bacterial blight (BB). To identify high-yielding varieties to replace

Sugandha, all available land races were collected, purified, and tested in varietal trials.

One of these is Katarni, which is grown intensively in the Bhagalpur division of Bihar. SBR 80-643-14-1-1, one of the six ecotypes of Katarni, yielded more than checks and was released as Kamini. During 5 yr of yield trials, Kamini averaged 2.9 t/ha, compared with 2.5 t/ha for check Sugandha (see table). Growers highly preferred Kamini to other varieties.

Kamini is tall, photoperiod-sensitive, and tolerant of brown spot, B1, and BB. It has excellent aroma and cooking quality, especially for palao, a specialty rice food. It is a late aman (Jun/Jul-Dec) season variety suitable for rainfed lowland conditions of Bihar and eastern Uttar Pradesh.

Table 2. Agronomic characters of promising rice hybrids. CLRRI, Omon, Vietnam, 1993 DS.

Growth Plant Panicles/ Grains/ Spikelet 1,000- Hybrid duration height plant panicle Sterility grain wt

(d) (cm) (no.) (no.) (%) (g)

lR62829 A/lR47310-94-4-3-1 R 105 lR58025 A/lR54742-22-19-3 R lR58025 A/lR532358-90-3-3 R 109 OM90-9 (check) 112

98 15.3

107 10.6 106 12.1

74 31 26

91 29 26 105 101 11.9 74 36 26

68 26 25


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-

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-

Performance of IRRI rice hybrids at RRI, Kala Shah Kaku, Lahore, Pakistan. 1992 kharif.

Heterosisa

Maturity Panicles/m2 Plant Panicle Spikelets/ 100-seed Spikelet Sterile Yield for yield over Hybrid and check duration (no.) height length panicle weight sterility plants (t/ha)

(d) (cm) (cm) (no.) (g) (%) (%) KS282 IR6 (%) (%)

lR62829 A/IR10198-66-2R 96 362 99 28.5 156 2.04 16.0 3.10 2.1 3.7 –9.2 lR62829A/lR15324-13-3-3-2R 97 304 81 26.4 158 1.96 27.6 3.35 1.9 –9.5 –20.8 lR62829A/lR28238-109-1-3-2-2R 103 240 84 23.7 138 2.02 30.2 3.33 2.0 –2.3 –14.4 lR62829A/lR29723-143-3-2-1R 98 326 84 26.0 189 1.92 25.3 7.23 2.5 18.9 4.1 lR62829A/lR35366-62-1-2-2-3R 103 333 78 25.4 160 1.87 38.7 6.37 1.8 –14.0 –24.7 lR62829A/lR40750-82-2-2-3R 111 346 93 27.3 233 1.88 31.3 4.13 3.1 47.9 29.5 lR62829 A/IR9761-19-1R 96 310 77 24.4 149 2.03 24.1 4.17 2.4 14.8 0.6 lR62829 A/Pusa 150-9-3-1R 98 256 84 26.2 155 2.09 32.3 5.31 2.0 –2.1 –14.3 lR58025 A/IR10198-66-2R 108 230 103 27.6 160 2.56 21.0 2.00 3.3 61.0 41.0** lR58025A/lR15324-13-3-3-2R 96 208 101 29.0 185 2.38 23.4 3.11 2.2 5.3* –7.8 lR58025A/lR20933-68-21-1-2-1 R 111 234 108 29.3 161 1.92 21.1 0.00 2.1 3.9 –9.0 lR58025A/IR21567-18-3 R 108 243 99 25.6 129 2.74 37.6 5.33 2.1 2.2 –10.5 lR62829A/lR28238-109-1-3-2-2R 104 246 101 27.8 170 1.89 39.6 8.15 2.7 32.4 16.0 lR58025A/lR29723-143-3-2-1R 108 234 103 25.6 115 2.03 28.6 0.00 2.8 36.1 19.2 lR58025A/lR32419-28-3-1-3R 103 211 102 29.0 203 2.17 33.0 6.55 1.8 –11.8 –22.8 lR58025A/lR35366-62-1-2-2-3R 104 202 95 27.5 199 2.33 31.1 5.98 1.7 –16.8 –27.1 lR58025A/lR39323-182-2-3-3R 103 195 93 30.3 234 2.38 33.4 7.10 2.6 24.3 8.9 lR58025A/lR40750-82-2-2-3R 119 274 94 23.9 152 2.12 23.5 2.30 3.6 74.8 53.0** lR58025A/IR66R 105 272 106 24.3 144 2.30 26.5 2.71 2.3 13.1 –1.0

lR58025A/Pusa150-9-3-1R 93 240 101 27.6 148 2.34 31.4 3.13 3.0 47.1 28.8 KS282 103 333 99 25.2 145 2.76 20.1 0.00 2.1 IR6 104 400 102 27.4 161 2.75 12.6 0.00 2.4

lR58025A/IR9761-19-1R 98 202 96 28.1 155 2.04 18.9 4.11 2.2 4.0* –8.9

LSD (0.05) 1.1 CV (%) 7.4

a * = better than low-yielding check KS282. ** = better than high-yielding check IR6.

plants/genotype per replication to measure plant height, panicle length, and spikelets/panicle. We used 100 seeds from the different randomly selected plants in each replication to measure 100-seed weight. Panicles/m2

per replication were counted. To determine maturity, duration days were counted from the date of transplanting to the stage of physiological maturity when about 90% of the grains were mature. Percent sterile plants per plot were counted and yield at 14% moisture level was recorded in t/ha.

Panicles/m2 ranged from 195 to 400, plant height from 77 to 103 cm, and panicle length from 23.7 to 30.3 cm. Spikelets/panicle ranged from 115 to 234 and 1 00-seed weight from 1.87 to

2.76 g. Maximum spikelet sterility was observed in IR62829 A/IR35366-62-1- 2-2-3R. Only hybrids IR58025 A/ IR40750-82-2-2-3R and lR58025 A/ IR10198-66-2R significantly outperformed all other hybrids and checks. The IR58025 A combinations, however, significantly outperformed IR62829 A hybrids and checks for most traits.

Of the 21 IRRI hybrids, eight performed significantly better than high-yielding check IR6 and three performed significantly better than KS282 (see table). IR6 had more panicles/m2 and heavier 100-seed weight than other hybrid combinations. IR58025 A/Pusa150-9-3-1R matured in 93 d, IR62829 A/IR40750-82-2-2-3R in 111 d, and IR58025A/IR40750-82-2-2-

3R in 119 d. These hybrid combinations showed 47.1,47.9, and 74.8% more standard heterosis over KS282, and 28.8,29.5, and 53.1% over IR6, respectively. Cross IR62829 A/ IR40750-2-2-3R showed 3.8, 8.4, and 61.2% more standard heterosis over KS282 for panicles/m2, panicle length, and spikelets/panicle, respectively.

Severe attacks of leaffolder and whitebacked planthopper, partial spikelet sterility (50-75% fertile spikelets for most genotypes), incomplete panicle exsertion, late transplanting of seedlings, and water stress at flowering caused low yields of hybrids and checks.


IR-Kesar: a brown planthopper (BPH)-resistant variety for Cambodia R. C. Chaudhary, IRRI; M. Sarom, O. Makara, and P. K. Hel, Ministry of Agriculture, Phnom Penh, Cambodia

Early rice varieties with duration of less than 120 d are grown during wet season (WS) as normal and August-seeded crops. They are grown during dry season (DS) as water-receding crops, which are seeded from Oct to Jan with no or partial irrigation, and as normal DS crops under full irrigation during Jan-Mar.

Most of the varieties planted are photoperiod-insensitive modern ones, the most popular of which are IR36, IR42, and IR50. During the past 3 yr, IR66,

IR72, and Kru have been spreading quickly. Weakly photoperiod-sensitive traditional varieties are also grown.

BPH is a serious pest during DS and occasionally during WS. Varietal resistances of IR36, IR42, and IR66 are no longer effective against BPH. Kru and IR72 are only the moderately resistant varieties available, thus the need for additional resistant varieties was realized.

Breeding line IR48525-100-1-2 was introduced to Cambodia from IRRI in 1989. The line is a cross of advanced breeding lines IR24632-34-2 and IR31868-64-2-3-3-3. The superior performance of IR48525-100-1-2 was observed in various trials in both DS and WS since 1990 (Table 1). IR48525-100- 1-2 yielded as much as IR50, IR66, IR72,

and Kru. Under serious BPH infestation, however, IR48525-100-1-2 outperformed other varieties (Table 2). It also has some resistance to leaffolder, gall midge, and stem borer. IR48525-100-1-2 was named IR-Kesar and recommended for testing at more than 190 locations in Cambodia during 1993.

Table 2. Performance of IR-Kesar (lR48525100- 1-2) in advanced yield trial at Prey Phdau (Kampong Speu Province) Research Station under severe BPH infestation. 1991 DS.

Entry Yield BPH score a

(t/ha) (0-9)

lR48525-100-1-2 4.0 1.5 lR48563-123-5-5-2 1.7 6.5 lR48613-21-3-2-2 2.9 2.5 lR50363-8-1-1-3 2.4 7.0 lR50363-61-1-2-2 1.9 6.5

Table 1. Performance of IR-Kesar (lR48525-100-1-2) and checks for seedling vigor, duration, height,

lR52280-64-3-3-3 BPH damage score, phenotypic acceptability (PAcp), and yield in various trials. Cambodia, 1990-92. lR51009-58-1-1-2 lR51008-89-2-1-2 2.6 3.5

1.8 5.5 1.7 6.5

Kru (check) 3.3 2.2 PYT, a 1990 DS PYT, early b 1990

(2 locations) (2 locations)

lR52256-203-2-2-3 1.6 6.0

Vigor Duration (d) Height (cm) PAcp Yield (t/ha)

Vigor Duration (d) Height (cm) PAcp BPH d

Yield (t/ha)

Vigor Duration (d) Height (cm) PAcp BPH d

Yield (t/ha)

IR-Kesar IR50

116 105 94 76

4.5 5.5 3.8 3.2

AYT, c 1991 DS (10 locations)

IR-Kesar Kru

2.8 3.0 116 113

86 80

1.5 2.2 4.74 4.68

AYT, 1992 DS (9 locations)

IR-Kesar Kru

1.8 2.8 114 108

88 83 3.0 4.3 0.3 1.5 4.37 4.32

IR-Kesar IR66 IR72

4.0 6.0 7.0 118 110 118

93 89 81 4.5 4.5 4.0 5.3 4.4 4.2

AYT, early 1991 (14 locations)

IR-Kesar Kru

3.0 3.6 115 113

87 84 2.5 2.5

4.20 4.46

AYT, early 1992 (17 locations)

IR-Kesar Kru

3.7 3.7 122 114

79 78 3.3 3.6

2.8 2.7

a PYT = preliminary yield trial. b Early season = Jan-Mar. c AYT = advanced yield trial. c Scored using the Standard evaluation system for rice.

Mean 2.4 4.8

a Scored using the Standard evaluation system for rice.

Lioto, a short-duration rice variety suitable for northern Zaire B. Mateso, K. M. Kasongo, K. Mbuya, N. Anzolo, and E. Mbuluku, Centre de Recherches Agronomiques de I’lnstitut National pour I’Etude et la Recherche Agronomiques, B.P. 2015, Yangambi via Kisangani, Zaire

Farmers tend to grow maize, peanut, and cotton rather than rice during the first cropping season (Apr-Aug) in Bambesa Zone of northern Zaire to avoid severe damage to the rice crop by birds and big rodents ( Thryonomys swinderianus ) called simbiliki. Rice is grown with fewer problems during the second season (Sep- Dec) when rain is often inadequate. Varieties such as IRAT112 have a short growth duration and are appropriate for late planting during the second season.

in Bambesa Zone since 1985 because of its short growth duration (110 d) and

IRAT112 (RY150) has been cultivated


Integrated germplasm improvement-rainfed lowland

– –

– –

Table 1. Plant characterlstics of 4 selected breeding lines at Bambosa, Zaire, 1989-91.

Line/variety Characteristic

R66 PR36-1-31 PR36-1-7-2 PR36-1-2-2 PR36-1-1-2 IRAT112 (check)

Life cycle (d) 124 116 116 116 115 115 Plant height (cm) 145 110 92 107 104 80 Lodging (score)a 3 1 1 1 1 1 Grain length (mm) 9.20 9.89 9.51 9.77 9.51 9.55 Brazilian Upland Rice Grain width (mm) 2.98 3.24 3.07 3.12 3.07 2.88 Grain thickness (mm) 2.15 2.40 2.28 2.35 2.28 2.83 Breeding Network: varietal L-W ratio 3.08 3.05 3.09 3.13 3.09 3.32 release, time span, and yield W-T ratio 1.30 1.35 1.35 1.32 1.35 1,000-grain weight (g) 31.8 37.2 30.0 32.0 30.0 31.90 Translucency (%) 81.7 73.6 77.8 75.0 79.5 72.4 Disease reactiona

E. P. Guirnaraes, Rice Program, Centro

Leaf scald MR R R R R R Leaf blast MS MR MR MR MR MR

1.02 increase

lnternacional de Agricultura Tropical, Apartado Aereo 6713, Cali, Colombia

Grain yield (t/ha) 2.7 3.2 3.0 2.8 2.8 2.9

a Scored using the Standard evaluation system for rice,

Table 2. Performance of 4 selected breeding lines at 3 locations. Zaire, 1989-91.

Grain yield a (t/ha) and increase over check IRAT112 (%)

Location IRAT112 (check) PR36-1-3-1 PR36-1-7-2 PR36-1-2-2 PR36-1-1-2

t/ha t/ha % t/ha % t/ha % t/ha %

Yangambi 2.8 2.8 3 2.7 0 2.5 –8 2.4 –13 Bambosa 2.9 3.2 11 3.0 4 2.8 –1 2.8 –1 Kiyaka 2.6 2.9 11 2.1 –10 2.8 10 2.9 11

AV 2.7 2.9 8 2.6 –5 2.7 1 2.7 –1

a Yield is av of 3 yr.

good grain quality. It resists blast and

characteristics of the breeding lines, quickly. They prefer a medium-height IRAT112 (Table 1). Grain quality panicles. The result is that they tire similar for the breeding lines and tall farmers, who must stoop to harvest reaction to leaf blast and leaf scald were practice of hand harvesting difficult for life cycle, lodging tolerance, and IRAT112, however, makes the common

At the Bambesa site, yield potential, 2.8 t/ha. The short stature (80 cm) of 25- × 20-cm spacing. leaf scald and yields an average of which 4-5 grains/hill were sown at

(100-140 cm) variety that is tolerant of lodging.

Local cultivar R66 was crossed with IRAT112 at Yangambi Research Station with the aim of creating a medium- height, lodging-tolerant, short-duration variety with good grain characteristics. Four breeding lines were selected from R66/IRAT112 and compared with IRATl12 at three sites (Yangambi, Bambesa, Kiyaka) from 1989 to 1991 (Table 1). The experiment was laid out in a randomized block design with four replications. Plots were 3 × 5 m, in

- except for 1,000-grain weight, were also comparable with those of IRAT112. PR36-1-3-1 had an advantage over all other materials tested for 1,000-grain weight. Plant height, however, varied among lines, with PR36-1-3-1 averaging 110 cm. Performance of PR36-1-3-1 was good and yields stable across three locations (Table 2).

PR36-1-3-1 was released as Lioto to replace IRAT112. Increased plant height and tolerance for lodging are its major advantages over IRAT112.

The state rice research institutions of Brazil formed the Upland Rice Breeding Network in 1982 to develop suitable upland rice varieties for the country's different regions. The National Rice and Beans Research Center (CNPAF) coordinates the network.

Twelve upland varieties released between 1985 and 1989 were analyzed for time between crossing and varietal release, time required for yield trials, and average increase in grain yield of new materials compared with previously released varieties. Our primary information sources were publications containing data from varietal release trials prepared by state research institutions and CNPAF.

Time between crossing and varietal release averaged 8.8 yr (Table 1). The first variety released, Cuiabana, required

Table 1. Varieties released to the Brazilian Cerrados Region by the Upland Rice Breeding Network, 1985-89. a

Variety YC YR TD YT TY

Araguaia 1978 1987 9 1983 4

Cabaçu 1979 1988 9 1985 3 C. America 1978 1987 9 1983 4 Cuiabana 1978 1985 7 1983 2 Douradão 1978 1989 11 1986 3 EMCAPA 01 1976 1985 9 1981 4 Guapore 1980 1988 8 1985 3 Guarani 1978 1987 9 1983 4 Rio Paranaiba 1978 1987 9 1984 3 Tangars 1981 1989 8 1985 4 Xingu 1980 1989 9 1986 3

BR-4 1976 1985 9 1981 4

Mean 8.8 3.4

a YC =year of crossing, YR = year of release, TD = number

TY = number of years under yield trials. of years from crossing to release, YT = year of trial,


Integrated germplasm improvement— upland

Table 2. Average yields of varieties released to the Brazilian Cerrados Region by the Upland Rice Breeding Network compared across states and with checks.

Variety State Yield Yield of Yield (t/ha) check b increase

(t/ha) (%)

Araguaia Goias 2.9 (45) a 2.4 [1] 19 BR-4 Piaui 3.2 (6) 2.2 [1] 43

Amapá 1.6 (3) 1.5 [1] 3 Roraima 1.9 (4) 1.7 [1] 17

Cabaçu C. América Cuiabana Douradão EMCAPA 01 Guaporé Guarani

Rio Paranaiba

Tangara Xingu

Mean

Goias M. Grosso M. Grosso M. Gerais E. Santo Rondonia M. Grosso M. Grosso SuI Goias M. Gerais M. Gross SuI Goias M. Gerais M. Grosso Para

2.7 (36) 2.3 (12) 1.7 (6) 3.0 (17) 3.3 (6) 3.3 (8) 2.6 (12) 2.2 (7) 3.2 (38) 2.5 (11) 2.6 (7) 3.2 (38) 2.5 (11) 2.3 (21) 2.5 (9)

2.2 [1] 2.2 [3] 1.4 [1] 2.4 [2] 2.9 [1] 1.5 [1] 2.2 [3] 2.1 [3] 2.7 [1]

2.4 [1] 2.7 [1]

1.9 [1]

1.9 [1] 2.1 [3] 2.1 [1]

21 6

18 25 14 16 17

6 16 31 5

16 31 12 18 17.3

a Numbers in parentheses are number of yield trials. b Numbers in brackets represent check: 1 = IAC47, 2 = IAC25, 3 = IAC165.

only 7 yr. This reasonable amount of time

from crossing to release (Table 1). program uses an off-season site. 3.4 yr, which was 38.6% of total time was possible because the breeding

Time required for yield trials averaged

Average years required provides a minimum for the safe interpretation of results before release. Yield trials in the Cerrados can be conducted only during the normal growing season and must be replicated over time to better assess the genotype × environment interaction.

We estimated regional yield increases from the network-released varieties by comparing grain yields of new varieties with those of checks in each trial. Percent yield increase was then added and divided by number of varieties, resulting in a 17.3% yield increase (Table 2). Overall mean (average yield of varieties and checks) showed a 20.9% increase. The average was 19.1% when number of trials was considered.

The network provided farmers with several new varieties from 1982 to 1989. Grain yield increased significantly as a result. Total upland rice production would increase by about 1 million t if all farmers used the new varieties on the 3.6 million ha planted to upland rice in Brazil, where current average yield is 1.3 t/ha.

Elite upland rice lines in Japan H. Nemoto, M. Hirayama, K. Okamoto, and M. Miyamoto, Plant Biotechnology

Characteristics of Kanto-mochi 168 and Kanto-mochi 172, IAC, Japan.

Days to heading

Length (cm) Blast resistance a

Culm Panicle Leaf Panicle Line/variety Yield

(t/ha)

Institute, lbaraki Agricultural Center (IAC), Kamikunii, Mito, lbaraki 305, Japan Kanto-mochi 168 125 71 20.1 1 0 4.2

Kanto-mochi 172 126 76 20.5 0 0 4.5 The importance of upland rice is decreasing in Japan. The largest upland rice area grown was 184,000 ha in 1960. Upland rice is now cultivated in rotation with vegetables on about 13,700 ha (0.7% of total cultivated rice area in Japan).

Systematic upland rice breeding in Japan was started in 1929. Since then, about 50 varieties have been bred and released to farmers. Most of the breeding materials came from Japanese traditional upland rice sources, a limited genetic pool.

We started screening for drought tolerance in indica and tropical japonica varieties in 1978 to increase genetic

Tsukubahatamochi 124 79 20.8 0 0 4.0

a Blast resistance scored using scale where 0 = resistant and 9 = susceptible.

variation. We found some drought- Kanto-mochi 168 is more tolerant of tolerant traditional indica, African, and water stress than Japanese varieties and Chinese varieties and crossed them with

Kanto-mochi 172 was bred from the Japanese upland varieties. Kanto-mochi has outstanding cooking quality.

varieties, but its yield ability is excellent. mochi means glutinous in Japanese. of this line is not as good as that of other the area code of our breeding team and Tsukubahatamochi. The cooking quality characteristics of these lines.) Kanto is IRAT109 and Japanese upland variety 172 in 1992. (See table for important cross of African upland rice variety 168 was bred in 1991 and Kanto-mochi

Kanto-mochi 168 was selected from We are evaluating these lines in local the cross of JC81 (a traditional indica adaptability tests. They will be useful variety introduced from IRRI) and genetic donors in future upland rice Norin-mochi 4 (a Japanese upland breeding. variety) that was backcrossed twice.


Yield performance of some rice lines in acid sulfate soils of Indonesia H. Rosmini, Banjarbaru Research Institute for Food Crops, P. O. Box 31, Banjarbaru, South Kalimantan, Indonesia

We compared 17 IRRI rice lines, 5 Indonesian lines, and checks Kapuas and IR36 in yield trials during the 1991-92 wet season (WS) in acid sulfate soils at Terantang and Unit Tatas (Table 1).

at 25- × 25-cm spacing in 4- × 5-m 2 plots with three replications. Plots were fertilized with 90-60-50 kg NPK/ha.

IR24637-38-2-2, and IR31432-7-2 significantly outyielded IR36 in Terantang (Table 2). Yields in Unit Tatas were lower than those in Terantang

Two seedlings/hill were transplanted

IR13426-19-2, IR21820-154-3-2-2-3,

Table 1. Some chemical characteristics of acid sulfate soils at Terantang and Unit Tatas, Indonesia.

Characteristic Soil (0-20 crn)

Terantang Unit Tatas

Total N (%) 4.0 4.0 0.2 0.4

Organic C (%) 2.9 2.8

Exchangeable K Available P (ppm) 1.7 1.7

(meq/100 g) 0.6 SO 4

-2 (%) 0.2

AI +3 (meq/100 g) 13.3 14.2 Fe (meq/100 g) 6.4 6.2 Na (meq/100 g) 0.3 0.2 Particle size (%)

Sand 0.6 Silt 69.3 62.0 Clay 30 37

1.2

because of the higher acidity stress, but 11 lines, including local check Kapuas,

both sites and appear suitable for

IR21820-154-3-2-2-3 performed well at advanced trials. outyielded IR36. IR24637-38-2-2 and sulfate soils. We have selected them for

growing in tidal swamp areas with acid

Table 2. Grain yield, maturity, filled grains/panicle, unfilled grains/panicle, panicles/hill, and plant height of some rice lines. Terantang [T] and Unit Tatas [U], Indonesia, 1991-92 WS.

Line/check

lR21820-154-3-2-2-3 lR24637-38-2-2 lR13426-19-2 lR31432-7-2 Kapuas (check) BW267-3 lR6023-10-1-1 lR15865-430-3-1 lR33353-64-1-2-1 CR261-7039-236 B5344-Sm-61-2-1

B5332-3d-Mr-84-3-1 IR51500-AC9-7

IR9884-54-3-El-P1 lR2071-105-9-1 lR31429-14-2-3 lR21567-16-3 lR21567-9-2-2-3-1-3 B6996d-Mr-5-3

IR36 IR11288-B-B-69-1

B6992d-99-KA-2 lR21836-90-3 B6992d-Mr-84-3-1

LSD (0.05) CV(%)

Yield (t/ha)

T U

6.2 4.3 6.1 3.3 6.0 2.8 5.9 2.5 5.8 4.1 5.8 4.1 5.8 3.3 5.8 3.1 5.7 2.5 5.6 2.1 5.6 2.3 5.6 4.1 5.4 2.0 5.3 3.3 5.3 2.3 5.3 1.4 5.3 2.8 5.2 3.5 4.9 2.4 4.8 4.0 4.7 2.0 4.6 2.9 4.4 2.1 3.8 3.2

1.1 0.9 24.2 18.9

Maturity (d)

T U

116 124 115 125 116 127 119 125 117 125 116 123 118 126 113 123 115 123 117 123 119 129 106 122 121 126 113 128 132 129 118 123 127 122 123 132 118 125 116 125 114 111 117 125 123 129 109 117

5.4 2.4 2.8 1.2

Filled grains/ Unfilled grains/ Panicles/hill panicle (no.) panicle (no.) (no.)

T U T U T U

109 100

99 96

122 123 129

98 78

134 109

71 93 97

121 79 74

116 69 77

104 116

85 78

35.7 21.9

104 25 98 22 78 20 71 19

112 12 101 33 108 32

78 20 82 25 97 24 84 55 76 13 82 21 66 26 80 29 74 23 82 34 99 27 92 23 68 30 69 18

100 29 58 21 78 21

23 18 26 16 27 17 25 15 25 15 29 14 27 12 25 18 31 16 26 14 42 13 20 12 32 15 32 17 31 13 29 14 22 15 33 14 28 11 23 16 23 11 35 12 45 13 24 12

12 10 12 10 11 11 10 10 10 10 13 13 10 13 11 8 8

12 10 13 11 10 11 15

31.3 13.1 11.6 4.2 2.9 22.3 31.8 24.5 17.9 16.4

Plant height (cm)

T U

98 86 104 89

91 82 108 86

92 90 112 101 118 107

99 86 102 88 102 86 107 100 100 87 116 101

97 87 108 96

96 87 84 82 96 99

100 87 93 81 68 68

116 89 101 98

92 81

8.6 9.1 5.2 6.2


pH

0.1

IRRN REMINDER

Routine research. Reports of screening

trials of varieties, fertilizer, cropping

methods, and other routine observations

using standard methodologies to establish

local recommendations are not accepted.

Examples are single-season, single-trial

field experiments. All field trials should be

repeated accross more than one season, in

multiple seasons, or in more than one

location as appropriate. All experiments

should include replications and an

internationally known check or control

treatment.

Integrated germplasm improvement— tidal wetlands

1.0

Effect of different doses of gamma rays on germination and survival of upland rice varieties S. S. Mehetre, P. A. Patil, C. R. Mahajan, and P. M. Dhumal, Botany Section, College of Agriculture, Kolhapur 416004, Maharashtra, India

Improvement in either a single or a few polygenetically controlled traits is normally not achieved by hybridization within a short time. Alternatively, targeted recombinations through induced mutation can be achieved within a short time without much disturbance of yield and grain quality in well-adapted varieties. This study was conducted to determine the response of eight varieties to different doses of gamma ray with the aim of determining the optimum dose for mutation breeding.

Healthy seeds of uniform size and moisture content of each variety were irradiated at the Bhabha Atomic Research Centre, Trombay, Bombay, with gamma ray doses of 10, 20, 30, 40, and 50 kr. Treated seeds were sown in the field in factorial randomized block design with two replications. Survival percentage was calculated as a percentage of germination based on numbers of plants 15 d after sowing and at harvest. Percentage reduction in germination and survival was calculated over the unirradiated control (see table).

ANOVA indicated varieties did not differ significantly in seed germination (see table) and that dose and dose × variety effects differed significantly. Percentage plant survival differed significantly among varieties and dose treatments but variety × dose effect was nonsignificant.

unirradiated varieties. Germination Average seed germination was 74% in

Effect of different doses of gamma rays on Varieties for their percent germination, survival, and reduction over control and ANOVA of partitioned sum of squares for gamma ray doses, varieties, and dose × varieties effect for percentage germination and survival. a

Gamma ray dose Germination Survival kr/variety

% % RG b % % RS c

Dose Control 10 20 30 40 50

Mean of doses (Without control)

Variety Jaya Ghansal JS180 Kundlika ACK5 R24 HS17 Basmati

Mean

ANOVA

SV df

Replications 1 Varieties (V) 7 Error (a) 7 Dose (D) 5 V × D 35 Error (b) 40

74.0 64.8 12.3 65.6 11.3 50.1 33.3

5.6 92.3 3.2 95.1

37.9 48.9

41.3 34.2 40.7 35.0 35.0 34.7 41.7 39.0 37.7

42.2 56.0 51.8 75.0 53.3 43.2 46.7 49.9 52.3

Germination (%)

SS F

230 145 0.9 ns 146

15901 484.7** 69 2.1* 32

94.2 88.3 6.1 84.1 10.6 91.7 2.5 50.1 46.7 45.5 51.6

72.0 23.5

74.5 66.5 45.6 53.5 92.0 92.0 77.5 72.1 71.7

19.1 33.4 46.7 44.2

4.9 1.0

17.1 24.2 23.8

Survival (%)

MSS F

3322 2376 5.8**

406 7662 16.2**

667 1.4 ns 472

a *, ** = significant and highly significant at P = 0.05 and 0.01, respectively. ns = nonsignificant. b RG = reduction in germination. c RS = reduction in survival.

decreased from 64.8 to 3.2% as gamma

highest in ACK5 and R24 (92.0%), cant reduction in germination (see table). kr. Seedling survival percentage was of 40-50 kr resulted in a highly signifi- increased from 10 to 50 kr, except at 30 kr did not differ significantly, but doses from 6.1 to 51.6% as gamma ray doses Germination percentage at doses of 10-30 reduction in seedling survival increased ray doses increased from 10 to 50 kr. followed by Ghansal(56%). Percentage

Lowest germination (34.2%) was although they had low germination observed in Ghansal, followed by R24 percentages. Highest seedling mortality (34.7%). Jaya (41.3%) and HS17 (41.7%) was observed in JS180. were found less sensitive when compared Based on percentages of germination with Ghansal and R24. Highest reduction and seedling survival, gamma ray doses in germination percentage over respective of 10, 20, and 30 kr were found to be control was recorded in Kundlika (75%), optimum for mutation breeding in rice.


Seed technology

–

–

–

–

–

–

– –

Characteristics of rice root growth under salt stress S. K. Dutt and A. R. Bal, Central Soil Salinity Research Institute, Regional Research Station, Canning Town, South 24 Parganas, West Bengal 743329, India

We conducted a sand culture pot experiment to investigate the characteristics of rice root growth under salt stress. Seedlings of tolerant CSR-1 and sensitive M1-48 were grown at salinity levels of EC 2.5, 5.4, and 12.7 dS/m, created by adding NaCl, CaCl 2 ,

and Na 2 SO 4 in a 7:2:1 ratio to Hoagland’s solution. Four replicates were made.

CSR-1 had greater root volume than M1-48 at both tillering and flowering stages (see table). Roots of CSR-1 were concentrated in the 15-30 cm layer; those of M1-48 were mainly in the 0-15 cm layer. Salinity did not affect root distribution pattern. As salinity increased, root volume and maximum root length were significantly reduced in M1-48 but not in CSR-1, and root dry matter increased marginally in CSR-1.

2. Relationship between relative percolation rate (RPR) and puddling depth (PD).

Crop and resource management ~

Puddling depth and soil texture influence percolation rate (PR) R. Khera and S. K. Jalota, Soils Department, Punjab Agricultural University, Ludhiana 141004, Punjab, India

PR without a clay layer was 4 mm/h for silt loam, 44 mm/h for sandy loam, and 83 mm/h for loamy sand. PR

Previous research has emphasized intensity of puddling to minimize percolation losses. Hydraulic conductivity of the puddled layer and the hydraulic head gradient across it theoretically control PR. Thickness of the clay layer on the soil surface is likely to influence hydraulic head gradient. Differences in thickness are due to differential settling of soil particles after puddling, which depends on soil clay content and puddling depth.

We conducted two experiments to study the effect of puddling depth and soil texture on PR. In the first experiment, three soils from Punjab were used. Soils were silt loam (53% sand, 29% silt, and 10% clay), sandy loam

(71% sand, 11% silt, and 10% clay), and loamy sand (86% sand, 6% silt, and 8% clay) with bulk density of 1.45, 1.50, and 1.60 Mg/m 3 , respectively. Soil columns (95 cm long × 10 cm inside diam) were saturated with water and PR was measured in two replications. Water influx was kept at a constant head of 2 cm. Clay particles from a slug put on the top of the soil column settled into layers 0, 0.43, 0.86, 1.72, 2.50, and 3.44 cm thick. Bulk density of the layer was 0.74 Mg/m 3 .

In the second experiment, puddling depth for each soil was calculated using volume-mass relations and clay content to bring into suspension the same amount of clay as that on top of the columns in the first experiment. Relationships between relative PR and puddling depth were developed for the soils.

decreased linearly with thickness of clay layer irrespective of soil texture, which was also true when soil was puddled to bring a specific amount of clay into suspension. (See Figure 1 for the relationship for silt loam.)

The exponential function explained RPR (PR/PR maximum) and puddling depth relationship in the three soils (Fig. 2). The regression coefficient increased with coarseness of soil texture. The intercept value of 1 satisfies upper and lower limits of the function, meaning that when puddling depth is zero, PR equals maximum PR, and when puddling depth is infinite, PR is zero.

These results suggest that to reduce PR to a specific limit, greater puddling depth is needed in coarser soils than in medium- textured soils. Puddling depth rather than intensity appears to help improve control of percolation losses with minimum deterioration of soil structure.

1. Relationship

layer at the thickness of clay lation rate and between perco-

surface for silt loam soil.


Soils

Physiology and plant nutrition

Plant water content and relative water content of leaves in both varieties, but especially in M1-48, showed a downward trend with increase in salinity and age. Sodium concentration in roots increased significantly as salinity increased. Variety M1-48 accumulated more sodium than CSR-1 during tillering and flowering stages.

Yield response of Basmati rice to applied P at different soil P values G. Hassan, E. H. Chaudhary, S. M. Mian, K. H. Gill, and A. A. Sheikh, Rapid Soil Fertility Survey and Soil Testing Institute, Punjab, Lahore, Pakistan

We measured yield of Basmati 385 in response to 0, 33, 66, and 99 kg P/ha in 32 farmers' fields in West Punjab, Pakistan. All treatments received 125- 62-4.2 kg NKZn/ha. Soils ranged from loam to clay loam, 8.0 to 8.4 pH, 0.84 to 3.1 dS/m EC, 3 to 20 mg Olsen's P/kg, 0.51 to 1.03% organic matter, and 132 to 351 mg ammonium acetate extractable K/kg.

We transplanted 35-d-old rice seedlings at 25- × 25-cm spacing. All of the P and K and half of the N was applied at last puddling, Zn at 10 d after transplanting, and the remaining N at panicle initiation. Yield was recorded at 14% moisture level. Data collected during 1990 and 1991 dry seasons (DS) were pooled and grouped into categories of low, medium, satisfactory, and adequate based on Olsen's P values. Each category was statistically analyzed and average values tabulated.

Yield increased significantly up to 33 kg P/ha for all soil P test values, but significant responses to the next higher dose was observed only when test values were less than or equal to 11 mg P/kg (see table).

Marginal rate of return (MRR) is target return from the last dollar invested on the purchase of an input. Yield data were used for curve-fitting at MRR values of 0.5, 0.1, and 1.5 to establish P rate recommendations for a given soil P test value (see figure). These curves facilitate site-specific recommendations on P use for Basmati 385 that accommodate soil P status and economic motives of a farmer.

Effect of salinity on root growth characteristics of rice.

Salinity Maximum Root Root dry Water Relative Na Concentration

(dS/m) (%) (cm 3 /plant) (g/plant) of plant of leaves (% DM) Variety level root length volume matter content water Content in roots

(%) (%)

Tillering stage 2.5 30.2 150.0 6.4 87.7 97.4 0.52

CSR-1 5.4 29.0 148.1 6.8 86.7 96.3 0.66 12.7 31.6 145.9 7.6 85.9 95.3 1.08

2.5 30.5 102.5 4.1 87.1 94.8 0.65

12.7 18.3 63.0 1.8 68.0 76.1 1.45 M1-48 5.4 30.5 87.8 3.3 82.6 89.9 0.93

Flowering stage 2.5 31.1 180.6 8.2 86.8 97.9 0.54

12.7 30.8 175.6 9.1 85.9 90.2 2.28

2.5 32.0 115.1 4.8 87.0 96.3 0.79

CSR-1 5.4 28.7 179.1 8.3 86.0 95.1 1.99

M1-48 5.4 30.5 98.3 3.5 83.0 88.1 12.7 19.6 62.9 1.6 65.0 76.0 2.71

LSD (0.05) 0.8 1.7 0.4 1.2 1.6 0.32

Soil test relationship curves for P at various marginal rate of return (MRR) values.

P applied Grain yield (t/ha) at soil P test value of

Average yield of Basmati 385 at different soil P levels under graded doses of P. West Punjab, Pakistan, 1990 and 1991 DS.

(kg/ha) 7 mg/kg (9) a 8-11 mg/kg (11) 12-15 mg/kg (7) 15 mg/kg (5)

0 2.6 c 3.4 c 3.6 b 4.0 b 33 3.3 b 4.1 b 3.9 ab 4.6 a 66 3.8 a 4.3 ab 4.3 a 4.5 ab 99 3.9 a 4.5 a 4.0 ab 4.3 ab

a Figures in parentheses are number of experiments. 18 were performed in 1990 and 14 in 1991. Figures followed by a common letter are not significantly different at 0.05 LSD.


2.38

Fertilizer management-inorganic sources

Effect of timing of basal N application on transplanted rice yield and N recovery S. K. Sharma, I. S. Chakor, and Vivek, Regional Research Station, Himachal Pradesh Krishi Vishva Vidyalaya, Dhaulakuan 173001, India

We studied effect of timing of basal N application on grain yield and N recovery of transplanted rice during 1990 and 1991 kharif (monsoon) seasons. Soil was sandy loam with pH 7.3, bulk density 1.33 Mg/

, 0.7% organic C, and CEC 17.9 c mol/

Experiments were laid out in a randomized block design with four replications (see table for treatments). We transplanted 25-d-old seedlings of variety HPH741 and applied recommended doses of phosphate and potash at 17.6 kg P/ha and 33.2 kg K/ha. Half of the

Distribution of 65 Z n in soil columns.

Effect of timing of N application on transplanted rice yield and N recovery, Himachal Pradesh, India, 1990 and 1991 kharif seasons.

Rice grain yield (t/ha) Fertilizer recovery (%) Treatment

1990 1991 1990 1991

N applied at transplanting 6.0 5.7 37.5 36.8 N applied at 7 DT a 6.1 6.1 43.6 44.3 N applied at 14 DT 6.9 7.1 55.9 57.2 N applied at 21 DT 6.1 6.4 44.2 46.1 N applied at 28 DT 6.4 6.0 36.7 35.9 N applied at 35 DT 5.9 5.6 35.1 34.7

LSD (0.05) ns b 2.1 3.0 3.0

a DT = days after transplanting. b ns = not significant.

recommended dose of 90 kg N/ha as urea was applied basally as per treatments; remaining N was applied at panicle initiation. Rainfall was 710.9, 419.3, 278.1, and 2.2 mm in 1990 and 98.6,322.8,40.1, and 1.2 mm in 1991 during Jul, Aug, Sep, and Oct, respectively.

Basal N applied 14 d after transplanting (DT) produced the most rice, which was significantly different from other treatments in 1991 only. The lower N recovery and grain yield observed for N compared with basal N at 14 DT might be explained by greater leaching losses of N at transplanting (see table).

m 3

kg.

Retention and movement of applied Zn in rice soils A. Raja Rajan, Radioisotope (Tracer) Laboratory, Tamil Nadu Agricultural University, Coimbatore 641 003, India

We studied the retention and movement of applied Zn in rice soils as influenced by organic matter, N, and P. Soils used were a sandy clay (Aquic Haplustalf) with pH 6.4,0.33 dS/m EC, 0.71% organic C, 0.08% total N, 0.22% total P, 0.32% total K, and 77.50 ppm total Zn, and a sandy loam (Vertic Haplustalf) with pH 8.2, EC 3.4 dS/m, 0.42% organic C, 0.04% total N, 0.12% total P, 0.22% total K, and 80 ppm total Zn.

Farmyard manure (FYM) at 0.5 and 1.0% on a soil-weight basis, urea at 30 and 60 ppm N and superphosphate at 6 and 12 ppm P were mixed with air- dried, sieved soil samples packed to a uniform bulk density of 1.3 g/cm 3 in PVC columns (35 cm long x 5 cm wide).

Five ppm Zn was applied as 65 Zn radiotracer-tagged ZnSO 4 to the top of each column and leached with deionized water for 168 h. A constant water head of 2.5 cm above the soil

surface was maintained. Leachates

period and monitored for radioactivity. were collected every 24 h during the

Soil in the columns was then divided

cm). Radioassay of soil samples and into three layers (0-5, 5-15, and >15

Treatments of FYM, N, and P at the leachates was done on a gamma ray

scintillator. movement. No radioactivity was detected spectrometer with a NaI-Tl crystal various levels had no effect on Zn

More than 90% of Zn applied as in leachates, suggesting that applied Zn ZnSO 4 remained in the top 0-5 cm was not prone to leaching but rather to layer in both soils. Very little Zn fixation. reached the lower layers (see figure).


Influence of green manure Table 1. Percent translocation of 65 Zn from applied fertilizer measured at harvest stage. a

(GM) Sesbania aculeata on Treatment Zn and S translocation in rice

Clay loam Sandy loam

Grain Straw Root Grain Straw Root S. Mythili, K. Natarajan, S. P. Palaniappan, and R. Pushpavalli, Centre for Soil and Crop ZnSO 4 51.5 Management Studies, Tamil Nadu EDTA-Zn Agricultural University, Coimbatore ZnSO 4 + GM 641003, India

22.3 26.3 40.4 32.7 26.9

33.8 29.0 37.3 33.9 27.1 39.0 EDTA-Zn + GM 42.1 31.0 26.8 32.6 18.0 49.4 ZnSO 4 + gypsum + GM 56.5 16.4 27.1 53.2 15.0 28.6

53.3 27.2 19.6 29.3 41.1 29.5

We evaluated the effect of GM S. aculeata on translocation of Zn and S to the grain, straw, and roots of short- duration rice variety ADT36 using 65 Zn and 35 S radioisotopes in a greenhouse Clay loam Sandy loam experiment. Zn was applied to soils as Treatment ZnSO 4 or EDTA-Zn at 1.0 m Ci/g Zn and S as gypsum at 0.2 m Ci/g S. A black, calcareous clay loam (Vertic

Gypsum 36.4 40.7 23.0 39.0 49.1

Ustropepts) with pH 8.0, EC 0.51 dS/m,

200 ppm total S and a red, noncal- careous sandy loam (Typic Haplustalf) with pH 7.1, EC 0.13 dS/m, 0.45% Biofertilizers enhance Between 0600 and 1600 h, DOC ranged

a Mean of two replications. Data not statistically analyzed.

Table 2. Percent translocation of 35 S from applied fertilizer measured at harvest stage. a

Grain Straw Root Grain Straw Root

11.9 Gypsum + GM 42.3 39.6 18.2 45.0 41.0 14.1 Gypsum + ZnSO 4 + GM 38.6 42.6 18.9 45.9 40.8 13.2

0.56% Organic C, 58 ppm total Zn, and a Mean of two replications. Data not statistically analyzed.

organic C, 47 ppm total Zn, and 180 ppm total S were used. Recommended levels of NPK were applied.

highest percent translocation to the grain of total Zn absorbed in both the clay loam (56.5%) and sandy loam (53.2%) (Table 1). More Zn accumulated in straw with EDTA-Zn than with ZnSO 4 . Zn retention in roots was highest with ZnSO 4 + GM (37.3%) in the clay loam and with EDTA-Zn + GM (49.4%) in the sandy loam. This high retention of Zn in roots without translocation evenly to grain and straw, especially with GM, reflects excessive Zn consumption.

Similarly, an increased translocation to grain of absorbed S occurred with gypsum + GM in both soils, with 42.3% in clay loam and 45.0% in sandy loam (Table 2). Sulfur supplied from the GM might have helped in the higher absorption and translocation of S to grain as compared with its translocation to straw and roots. Information reported is from a tracer study; sufficient replications could not be included to establish facts by statistical significance.

ZnSO 4 + gypsum + GM recorded the

dissolved oxygen content (DOC) in water

from 3.7 to 7.1 ppm in the BGA nursery, from 1.3 to 5.5 ppm in the azolla nursery, and from 3.1 to 5.4 ppm in the control

A. Lakshmanan, S. Anthoni Raj, and where water was impounded without A. Abdul Kareem, Tamil Nadu Rice Research BGA or azolla. Most samples from the Institute (TNRRI), Aduthurai 612101, lndia

BGA nursery had higher DOC than did Continuous cultivation of blue-green algae (BGA) and azolla is suspected to cause pollution. A study of BGA and azolla nurseries under continuous submergence for more than a year, however, revealed an enhanced DOC in the water. DOC increased between 0600 and 1600 h but declined thereafter.

those from the control. DOC in the control was higher than that in the azolla nursery, except at 1600 h (Table 1). CO 2 evolution was 61 mg/h per m 2 in the azolla nursery, which was more than in the BGA nursery (46 mg/h per m 2 ) and control (10 mg/h per m 2 ) (Table 2). Although CO 2 emissions may contribute

Table 1. DOC and temperature in BGA and azolla nurseries at TNRRI, Aduthurai, India, Jun-Sep 1992.

Sampling time (h)

0600 0800 1000 1200 1400 1600 1800 Parameter

Dissolved oxygen a (ppm) Control 3.1 5.4 5.3 5.0 5.0 4.7 4.2 BGA nursery 3.7 4.5 6.0 6.8 6.9 7.1 4.2 Azolla nursery 1.3 2.2 3.9 4.2 4.5 5.5 3.3

Temperature (°C) Control 25 29 33 38 42 37 32 BGA nursery 25 29 34 38 41 36 32 Azolla nursery 23 28 30 34 39 34 31

a Mean analysis of 2 d.


Fertilizer management — organic sources

Table 2. Evolution of CO 2 in BGA and azolla to atmospheric pollution, increased DOC nurseries at TNRRI, Aduthurai, India, Jun-Sep in water associated with biofertilizers 1992.

CO 2 evolved (mg/m 2 )

12 h a 24 h Source

Control 120 (10) b 240 (10) BGA nursery 550 (46) 1100 (46) Azolla nursery 480 (40) 1460 (61) a 0600-1800. b Figures in parentheses denote CO 2 evolved (mg/h per m 2 ).

might alleviate problems related to stagnant water. Augmenting DOC in continuously submerged fields where BGA and azolla are grown might also eliminate accumulated reduced iron and sulfides, which are toxic to rice.

Biomass and N content of S. aculeata variety during short-day Sesbania rostrata mutant months of Jan and Feb and long-day

with long vegetative phase months of Jun and Jul. S. sesban was included in the Jun-Jul study. The

D. C. Joshua, S. Ramani, and M. S. Shaikh, Nuclear Agriculture Dlvision, Bhabha Atomic Research Centre, Trombay, Bombay 400085, India

TSR- 1 (Trombay S. rostrata- 1), the late- flowering mutant of S. rostrata, remains insensitive to critical inductive photoperiod up to 60 d after planting (DAP). It has the potential to produce sufficient biomass regardless of time of sowing.

We evaluated the performance of TSR-1, the parent cultivar, and local

experiment was laid out in a randomized block design. Net plot size was 2.3 m 2 . Plant height, fresh weight, percent N, and N/plant were determined at 50 DAP.

TSR-1 was significantly superior to its parent and S. aculeata for biomass and N/ plant during Jan-Feb (Table 1). During Jun-Jul, TSR-1 performed as well as its parent and the other species for all parameters; it had marginal superiority for N/plant (Table 2). TSR-1 can be grown for biomass production during months of long or short photoperiods.

Table 1. Data from yield trial of TSR-1, Jan-Feb, Bombay, India.

Plant height Fresh weight %N N/plant Variety/species (cm) (kg/Plot) (whole plant) (g)

S. rostrata

S. aculeata TSR-1

90.0 2.5 3.7 6.12 126.5 4.1 3.6 9.33

93.5 1.6 3.6 18.8

4.19 0.5 0.7 2.99 LSD (0.05)

Table 2. Data from yield trial of TSR-1, Jun-Jul, Bombay, India.

Plant Fresh %N N/ Variety/ height weight plant species (cm) (kg/plot) Leaf Stem (g)

S. rostrata 187.5 6.1 5.6 1.7 0.92

S. sesban 132.3 6.0 5.4 1.4 0.87 S. aculeata 165.3 5.9 5.2 1.9 1.12

LSD (0.01) 33.8 1.6 0.4 0.6 0.38

TSR-1 186.5 6.0 5.4 1.8 1.22

Analysis of genetic diversity and population structure of bacterial blight (BB) pathogen in West Java, Indonesia E. Ardales, M. Baraoidan, I. Yap, T. W. Mew, and R. Nelson, IRRI; M. Yunus, H. R. Hifni, M. Herman, and M. Bustaman, Central Research Institute for Food Crops, Bogor, Indonesia

BB, caused by Xanthomonas oryzae pv. oryzae (Xoo), is the most important disease of lowland rice in Indonesia in the wet season. To develop high- yielding varieties with durable resistance to BB, it is necessary to understand the pathogen population structure. We conducted an initial analysis of genetic diversity and population structure of Xoo in West Java using molecular marker techniques.

1. TNX1 haplotypes defined from the Indonesian Xoo isolates (A-D) and the predominant haplotype (Ill-B) observed for race 3 in Central Luron, Philippines. M = DNA molecular weight markers.


Integrated pest management— diseases

2. Dendrogram obtained by UPgMA cluster analysis of the six TNX 1 haplotypes defined from the Indonesian Xoo population showing their phylogenetic relationships.

A total of 125 Xoo isolates—51 from the collection maintained in the Plant Pathology Department, Bogor Research Institute for Food Crops, and 74 collected from several fields near Sukamandi and Kuningan in Aug 1992—were subjected to DNA typing by restriction fragment length polymorphism (RFLP) using the DNA probe TNX1 and by digestion with the restriction enzyme Pst I.

RFLP analysis using TNX1 revealed six distinct RFLP profiles or haplotypes (Fig. 1). The phylogenetic relationships among these haplotypes were determined by cluster analysis of similarity coefficients by the unweighted pair-group method, arithmetic mean (UPGMA) using the computer program NTSYS. Four distinct lineages were defined at 95% similarity level (Fig. 2). Lineage A, which accounted for 75% of the isolates, had three variants: A, A-1, and A-2. The majority of isolates (68%) were type A. Type A-1, which was observed in 28% of the isolates, was identical to the predominant TNXl haplotype observed for race 3 in Central Luzon, Philippines. The third variant, A-2, was a rare type and detected in only two isolates (1%) collected from the same field. The three other haplotypes—B, C, and D—were also rare and detected in only one isolate each.

Only 19 of the isolates analyzed (15%) had Pst I-digestible DNA. DNA

from the rest of the isolates was uncut by the enzyme. The Pst I restriction patterns observed from the Indonesian Xoo isolates were distinct from those seen from the Philippine Xoo isolates.

The total genetic or haplotypic diversity of the Indonesian Xoo population analyzed was estimated using Nei’s haplotypic diversity index and found to be low (H T =0.47), based on TNX1-RFLP data. This low level of genetic diversity could be due to rice crop uniformity and stable climatic conditions (no typhoons). The apparent simplicity of Xoo populations in West Java implies that BB in Indonesia might be easy to manage; however, the sample size

analyzed was not large, the collection was not from widely diverse locations, and the phenotypic variation of the population—in terms of virulence on rice hosts carrying different resistance genes—remains to be analyzed.

Further expansion and analysis of the collection, in terms of geographical and host genotype representation, are needed before we can draw firm conclusions. RFLP analysis of a more geographically diverse collection of isolates obtained from different islands of Indonesia is currently underway. Isolates representing each of the RFLP types or groups will be used for evaluating potential sources of resistance to BB in Indonesia.

Use of DNA probes to distinguish mycoplasma-like organisms (MLOs) of yellow dwarf (RYD) and orange leaf (ROL) in rice K. Nakashima, Tropical Agriculture Research Center, Tsukuba, Japan; P. Q. Cabauatan and H. Koganezawa, IRRI

The pathogens causing RYD (common in Asia) and ROL (common in Southeast Asia) cannot be distinguished morphologically from each other, although the diseases are different in terms of symptomatology and vector transmissibility. Their taxonomical relationship has not been clarified.

chromosomal and extrachromosomal We cloned Hind III-cut fragments of

DNA from the Tochigi line (Japan) of RYD-MLO. The homology of DNA probes with several lines of RYD-MLO and with a Los Baños line of ROL-MLO was examined by dot-blot hybridization. DNA probes were labeled with horseradish peroxidase using the Amersham enhanced chemo- luminescence (ECL) system. The DNA- blotted nylon membranes were hybridized with the probes at 42 °C for 16 h in ECL hybridization solutions. The membranes were washed twice at 42 °C for 20 min in 0.5 × SSC (7.5 mM sodium citrate, 75 mM sodium chloride, pH 7.0) containing 6 M urea and 0.4% sodium dedocyl sulfate (SDS), once at 42 °C for 20 min in 0.01 × SSC-0.1% SDS, and once at 42 °C for 20 min in 0.01 × SSC-

Summary of results from dot hybridization of RYD-MLO DNA probes to DNA preparations. a

Origin Chromo- Extrachromo- somal somal DNA

Code Sample probes probes

Country Area R30 R9 R11 R19 R72

H Healthy rice J RYD-MLO Japan Tochigi T RYD-MLO Thailand Chachoengsao L RYD-MLO Philippines Luzon P RYD-MLO Philippines Palawan M RYD-MLO Philippines Mindanao 0 ROL-MLO Philippines Los Baños, Laguna

Other MLOs b

+ + + + + + + + + + + – w –

++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ w w w

a ++ = strong hybridization signal, + = moderate hybridization signal, w =weak hybridization signal, - = no hybridization signal. b Sugarcane white leaf, sesame phyllody (Thailand), onion yellows, cineraria witches' broom, Japanese hornwort witches' broom, water dropwort yellows, gentian witches' broom, udo dwarf, tsuwabuki witches' broom, pelargonium witches' broom (Japan), peach estern X, and pear decline (USA).


– – – – –

– – – – – –

Detection of DNA of RYD- and ROL- MLOs in rice leaves using probes of RYD- MLO, R30, R9, and R11. a

a H = healthy, J = Japanese line of RYD, T = Thai RYD, L = Los

Palawan (Philippines RYD, M = Baños (Philippines) RYD, P =

Mindanao (Philippines) RYD. and 0 = Los Baños (Philippines) ROL.

0.1 % SDS. Signals were detected with ECL method.

Chromosomal DNA probe R30 (2.8 kb) hybridized with ROL-MLO as well as RYD-MLO. R30 also detected all MLO lines used in the experiments, including sugarcane white leaf, gentian witches' broom, onion yellows, water dropwort yellows, and others. RYD- specific chromosomal DNA probe R9 (3.4 kb) and extrachromosomal DNA probes Rll (2.6 kb), R19 (4.6 kb), and R72 (1.2 kb) hybridized with all of the RYD-MLO lines, but not with ROL- MLO. RYD collected from Mindanao, Philippines, gave weaker signals with extrachromosomal DNA probes than the other RYD lines (see table and figure).

These results indicate that the MLO causing ROL is genetically different from the RYD-MLO. ROL-MLO can now be distinguished from RYD-MLO by using DNA probes from RYD-MLO.


Toxin produced by Sacrocladium oryzae involved in inducing sheath rot (ShR) symptoms in rice T. Vasantha Devi and S. S. Gnanamanickam, Center for Advanced Studies in Botany, University of Madras, Madras 600025, India

ShR, caused by the fungal pathogen S. oryzae, has become a major production constraint as more densely planted, N-responsive, high-yielding rice cultivars are used in India. Reports conflict on the success of chemical control of ShR.

Association of a toxin with ShR symptoms had not previously been established. Some of our earlier work, however, confirmed reports by Japanese researchers of cerulenin production in culture. We found that artificially applying cerulenin induced rotting of rice sheaths like that induced by S. oryzae.

fields in Tamil Nadu, Karnataka, and Pondicherry states and obtained 40

We studied ShR incidence in farmers'

isolates of S. oryzae from infected tissues and seeds. Isolate No. 22, which came from the most severely ShR- infected field, was the most virulent on TKM9, IR20, and IR50 plants in greenhouse inoculations.

Production of cerulenin by S. oryzae isolates was assessed by the inhibition of Candida albicans KF-1 in potato dextrose agar (PDA) plates in repeated laboratory assays. Virulent isolates produced larger inhibition zones (Fig. l), and low virulent isolates produced smaller inhibition zones. Most virulent isolate No. 22 produced a 30-mm- diameter zone and least virulent No. 6, a 6-mm-diameter zone. Amending PDA assay plates with lauric and oleic acids at 1-1000 ppm reversed the action of cerulenin-induced inhibition and confirmed the presence of cerulenin, which inhibits fatty acid synthetase.

We generated cerulenin-negative mutants of isolates No. 22 and No. 6 using UV irradiation. The mutants did not inhibit C. albicans KF-I or other fungal pathogens of rice including Pyricularia grisea, Helminthosporium oryzae, Rhizoctonia solani, and Gaumannomyces graminis var. oryzae in

1. Candida albicans KF-1- inhibition assay for cerulenin production of S. oryzae and control (right).

2. Induction of ShR symptoms (indicated by arrows) by wild- type (a) and no induction by cerulenin-negative mutant (b) isolates of S. oryzae.

plate assays, but the cerulenin-producing wild-type isolates did. Grain inocula of the mutants did not induce ShR lesions on 55-d-old TKM9 and IR50 plants in the greenhouse; the wild-type isolates did (Fig. 2). The No. 22 mutant did not

induce ShR on TKM9 and IR50 and did the toxin produced by S. oryzae, may not affect grain yield (grains/panicle,

These results indicate that cerulenin,

induction. rice. No. 22 affected grain yield due to ShR action with other fungal pathogens of weight) in a field experiment. Wild-type ShR induction in rice and in its inter-

play a role in the pathogen's virulence in infected grains/panicle, and 1,000-grain

30% WH meant the farmer was expecting a yield loss of 30% compared with a

Farmers’ estimates of percent planted after 15 Aug. In previous seasons, season without SB damige. Farmers’ whiteheads (WH) they had been planted as early as June. estimates compared with actual yield

It was not clear how farmers estimated reductions were nonsignificant using t- A. A. Lazaro, E. G. Rubia, L. P. Almazan, and K. L. Heong, IRRI percent WH. A few counted damaged

On the other hand, computed percent tillers and then divided by total tillers of test.

We conducted a study to compare farmers’ estimates with actual counts of WH caused by stem borers (SB) in 24 ricefields in Muñoz, Nueva Ecija, Philippines, in Nov 1992. Varieties planted were IR64, IR42, C-1, and Bengawan. We marked a 40- × 40-hill area in the middle of each field and asked farmers to estimate percent WH in the area. We then counted WH and total tillers in the area and computed percent damage. We recorded yield at harvest and highest yield obtained from the same field in previous seasons. Percent yield reduction was computed as yield divided by highest yield from previous seasons multiplied by 100.

All farmers attributed the unusually high WH count in their fields in 1992 wet season (WS) to late planting resulting from the delayed arrival of irrigation water. All ricefields sampled were

one or two hills near the bunds. Others based their estimates on experience or intuition.

Farmers tended to overestimate by 5-44%. Seventy-five percent overestimated by more than 5%, and almost 30% of these overestimated by 20-30%. Only two farmers underestimated (see figure). A t -test comparison between estimates and actual percentages showed that estimates differed significantly from actual percent damage by a mean difference of 13% (SE = 2.77).

Overestimates can influence farmers' decisions in applying controls. Some admitted applying insecticides after seeing WH, although it is too late to spray for SB when damage is evident.

Farmers equated percent WH to percent yield reduction. They all expected about the same reduction in yield as the WH estimate they had given. An estimate of

WH differed significantly from actual reductions in yield. This means that farmers made good estimates of their expected yield losses due to SB. Actual percent damage, however, did not coincide with percent yield reduction, which disproved their statement that percent WH equals percent yield reduction.

yield losses greater than actual SB damage. The estimates they gave, however, were fairly close to percent yield loss they obtained. This means that factors other than WH caused greater yield reduction. Farmers attributed these differences to factors such as poor soil, lack of fertilizer, late planting, and unfavorable weather. Farmers need to pay more attention to these factors before worrying about SB.

About 70% of the farmers obtained

Managing thrips in the Mekong Delta, Vietnam Nguyen Bin, Le Minh Tue, and Tran Thi Hong Hoa, Plant Protection Department, An Giang Province, Vietnam; and K. L. Heong, IRRI

Thrips Stenchaetothrips biformis infestations in Vietnam usually occur about 10 d after sowing (DAS) and are highly visible. Farmers often react by

Distribution of spraying insecticides which can be farmers' estimates of

detrimental to the rice crop by making it more susceptible to brown planthoppers. percent WH in

Nueva Ecija, We evaluated several thrips manage- Philippines. ment tactics (see table) at the Dinh Thanh 1992 WS. experimental station in An Giang

Province from Dec 1992 to Mar 1993.

four replications; plots were 4 × 4 m 2 . Fertilizer was applied at 46 kg N/ha as urea and 40 kg P/ha as diammonium phosphate at 10 DAS, 46 kg N at 25 DAS, and 23 kg N at 45 DAS. Rice variety MTL 58 was seeded at 200 kg/ha.

Thrips infestations were assessed using three 20- × 20-cm 2 quadrats per plot. Percent rolled leaves at 1 and 2 wk after sowing (WAS) was not significantly different. At 3 WAS, percent rolled leaves was lowest in the BPMC-treated plots. Yields, however, were not significantly different across treatments (see table).

We used a randomized block design with


Integrated pest management-insects

Comparison of thrips management tactics in An Giang Province, Vietnam. Dec 1992-Mar 1993.

Rolled Management Cost/ha leaves at Yield tactic (US$) 3 WAS a (t/ha)

(%)

50 kg N at 20 DAS 11 Flood with water -

Flood with water 11 5-10 cm deep

and add 50 kg N at 20 DAS

(500 ml ai/ha) at 7 and 14 DAS

Spray with BPMC 17 (500 ml ai/ha at 7 and 14 DAS) and add 50 kg N at 20 DAS

Spray with BPMC 6

Control

P

90.7 a 4.5 73.1 b 4.8

72.2 b 5.2

45.8 c 4.9

45.8 c 5.3

91.3 a 4.8

<0.01 >0.05

a WAS = weeks after sowing.

Crops infested by thrips can look terrible. Applying BPMC reduced symptoms, as did flooding, but neither treatment significantly improved yields. BPMC treatment cost $6/ha. Farmer education is needed to avoid unnecessary treatments for thrips in the Mekong Delta.

emerging within 15 h of incubation in the laboratory were released for 24 h into 3-cm-diam, 30-cm- high mylar cages with a 60-d-old rice plant trimmed to four tillers. Each cage was infested with BPH and GLH adults at densities ranging from 1 to 9 per cage with 10 replications.

In preference experiments, mixed densities of BPH and GLH adults at oviposition on caged rice plants were used to test A. flaveolus reared on both BPH and GLH eggs. Each density was replicated 10 times. Data were fitted to the random parasitoid equation of Royama (1971) and Roger (1972):

where N a is number of hoppers attacked, N is hopper density, a is attack rate of parasitoid, T is total search time, and T h is handling time. Estimates of a and T h were obtained using Proc. NLIN of SAS.

For preference, data were analyzed using Manly’s index a:

where n 10 is number of items of food type i (BPH or GLH eggs) present at the beginning, r i is number of items of food type i in consumer’s diet, and m is number of food types.

Data fit the random parasitoid equation satisfactorily (Table 1) and showed a typical Holling type II response. Searching efficiency was significantly higher for BPH eggs than for GLH eggs. The handling time for BPH eggs was lower, resulting in a higher plateau of prey attacked. This implies that A. flaveolus had a much higher searching efficiency for BPH eggs.

In all cases, A. flaveolus showed strong preference for BPH eggs (Table 2). Values of a were always greater than 0.5, irrespective of the relative proportion of BPH eggs to total number of GLH eggs. Host preference switching was also not evident.

Parasitism of brown Table 1. Parameter estimates of the functional response equation for A. flaveolus feeding on eggs of BPH and GLH. IRRI, 1993.

planthopper (BPH) and green leafhopper (GLH) eggs by Anagrus flaveolus Waterhouse T. N. Vien and K. L. Heong, IRRI

With the exception of a few species, almost all hopper species attacking rice in Asia belong to families Delphacidae and Cicadellidae. Egg parasitoids belonging to families Mymaridae and Trichogram- matidae are some of the most important natural enemies that attack these hoppers. High parasitism, particularly by A. flaveolus, is often recorded in the field.

We measured parasitism of A. flaveolus on eggs of BPH and GLH and determined the parasitoid’s

Parameter Asymptotic CV F R 2

Eggs estimates SE (%) (%)

A. flaveolus emerging from BPH eggs BPH a' 3.374 1.515 23.72 907.9 95.38

GLH a' 0.046 0.021 109 46.9 51.89 T h 0.020 0.002

T h 0.139 0.170

A. flaveolus emerging from GLH eggs BPH a' 0.766 0.097 18.13 1567.2 97.47

GLH a' 0.076 0.024 77.41 88.1 66.70 T h 0.015 0.002

T h 0.106 0.060

Table 2. Analysis of preference of A. flaveolus feeding on BPH and GLH eggs. IRRI, 1993.

Preference for BPH, a a (x ± SE)

Estimated using ratio of a' values

Estimated using Manly’s index

preference when exposed to both. We trapped A. flaveolus in ricefields and

A. flaveolus from BPH eggs 0.989 0.981 ± 0.029 n = 87 A. flaveolus from GLH eggs 0.909 0.943 ± 0.004 n = 89

cultured them in an insectary. Females a a was significantly different from 0.5, p < 0.05.


N a = N{1- exp[aT/(1 + aT h N)]}

Egg-laying behavior of African white rice borer Maliarpha separatella Ragonot A. Pollet, Entomology Laboratory, Gadjah Mada University, Yogyakarta, Indonesia

We used a simple analysis of spatial distribution of egg masses to study the egg-laying behavior of M. separatella.

M. separatella is a very common stem borer (SB) of lowland rice in Africa. The insects rest on wild plants in ricefield borders during the day and fly into ricefields at night to mate or lay eggs. M. separatella has a limited flight range. Females have relatively high fecundity rate (500-600 eggs/female). They usually lay eggs in masses of 40-50 eggs each during an 8-10 d period.

IR5 during the 1985 wet season (WS) in central Côte d'Ivoire. We sampled a 30-m 2 ricefield (3 subplots of 10 x 1 m) every 3d day from 31 Apr to 3 Jun, when no new egg masses were found.

We tested for goodness of fit. Mean of studied data was 2-3 times greater than their variance (0.67 compared with 0.27); thus fitting the observed data to a Poisson distribution was impossible (see table). Using the method of Bliss and Fisher (1953), we fit data to the negative binomial law by computing the following intermediate parameters:

process based on maximum likelihood theory), and

Egg population was studied on variety

k = 0.168 (obtained using an iterative

Observed distributions of numbers of egg masses per m 2 of ricefield and expected frequencies computed for the negative binomial and Poisson distribution. Values and probabilities of their corresponding c 2 and other statistics are shown. Central Côte d'lvoire, 1985 Ws.

Square meters Medium A × no. of egg masses Observed Negative binomial Poisson

n n' n "

0 1 2 3 4 5 6 Sum

P ( c 2 ) df Mean Variance k

281 29 10

3 5 1 1

330

0.27 0.65 0.168

280.98 29.04 10.46

4.66

1.17 0.62

329.21 3.9 0.691 3

2.28

250.80 67.72

9.14 0.82 0.06 0.00 0.00

120.87

2

328.54

<0.005

Distribution of egg masses on rice mapped for half of the 30-m 2 field, based on observations every 3 d from 29 Apr to 3 Jun a . Central Côte d'lvore. 1985 WS.

a No egg masses were found on 3 Jun, so no data are shown.


c 2

from which results all expected frequencies n' i (see table) using the next recurrent formula

where k, p, and q are parameters of the negative binomial (q-p) -k , m x is the mean of data from the n unit samples (n = 330 m 2 ), P 0 is probability of the first expected frequencies of n' 0 and n' i and n' i-1 are any two successive expected frequencies with indices of i-1 and i.

Observed frequencies n i were similar to the expected values n' i that could have been obtained if all egg masses were distributed according to negative binomial distribution (see table). The corresponding (3.9), gave too great a risk a (0.691) of being wrong when rejecting the null hypothesis.

The observed data must therefore be contagiously aggregated. Considering the holistic behavior of the insect, that they are not social insects, and that observed egg mass numbers are too small, such a grouping of data does not result from

females forming a group on a given night to lay eggs (see figure) and is not frequently done at random. It also could not result from accumulated eggs laid night after night in the same place by a few females.

Females can lay more than one egg mass a night, and all of these masses are located very close to one another. Different groups of egg masses resulted from the same number of individual females (see figure). Other experiments in different areas of Côte d'Ivoire supported these results.

Feeding behavior of parakeets on rice in Hill Region of Karnataka, India A. K. Chakravarthy. K. Krishnappa, and N. E. Thyagaraj, Regional Research Station, Mudigere 577132, Karnataka, India

Roseringed parakeet Psittacula krameri Scopoli and blossom-headed parakeet Psittacula cyanocephala Linn. are the two main bird species that feed on rice in the Hill Region of Karnataka.

parakeets to 4 ha of rice at Mudigere (13.0° 7' N and 75.0° 37' E) during Nov- Dec 1990. We used binoculars to observe the birds. We saw birds alighting on trees bordering ricefields at 0640 h. Most perched on tree branches or fence wires. At about 0720 h, three or four birds started to ricefeed in the fields. At about 0730, foraging groups of up to 20 birds of both species flew into the fields.

Individuals hovered by rice plants, cut, and then picked panicles. Each bird picked six to eight panicles during a period of 5-30 min, returned to its site, fed on the grains, and then flew back to the fields.

From 1000 to 1500 h, parakeets sought cover in trees adjacent to the ricefields. After 1500 h, five to six birds resumed feeding, which continued until

We studied damage done by


about 1745 h. Birds then returned to their roosting sites.

preening, beak cleaning, and resting. Individuals and groups spread over a wide area in a field but stayed within sight of each other. In 95% of the situations, the 55 flocks observed congregated only at field borders.

Foraging range of feeding flocks was 3-4 km and feeding range, 1.5-2.0 km. Flock size varied from 50 to 113 birds/ha (n = 55). Rice feeding lasted up to 24 d. Parakeets depredated stacked panicles soon after harvest. Birds preferred harvested panicles to panicles on the standing crop because they could feed conveniently on grains without hovering.

Foraging activity was interspersed by

Effect of selected genera of plant parasitic nematodes on germination of rice seeds in eastern India B. P. Hazarika, Indian Council for Agricultural Research Complex for Northeastern Hill Region, Manipur Centre, lmphal 795004, India

Rice in eastern India is seeded shortly after the premonsoon showers. In this situation, nematodes attack emerging seedlings and cause mortality.

We recorded seed germination in soils inoculated with nematodes to study their potentiality (Table 1). Results showed that only H. mucronata reduced seed viability significantly. We found that nematodes penetrated the seeds, affecting the embryos or inhibiting the emergence

Panicle loss was computed as parakeets/ ha × panicles/parakeet/day × feeding days. Panicle loss was converted to grain weight by counting and weighing all grains/panicle from a random sample of 100 panicles on eight different observation days.

Total yield loss was categorized as depredative loss (grain consumed) and extra-depredative loss (grain spilled). Mean depredatory loss of 71.4% differed significantly (P = 0.05) from the mean extra-depredative loss of 14.2% (n = 8).

Farmers lost 0.3 t/ha to parakeets. Considering that average harvest in Mudigere is 2.5 t/ha, yield loss caused by parakeets is economically important. Rice crops from milk grain stage to harvesting need to be protected from parakeets.

Table 1. Effect of selected genera of plant parasitic nematodes on germination of Jaya seeds in eastern India.

Treatment Germination Reduction (%) (%)

Uninoculated 96.0 – Meloidogyne 94.5 1.5 (6.8) a

(100 2d-stage juveniles)

Hoplolaimus (100) 90.5 5.5 (12.9) Pratylenchus (100) 90.0 6.0 (14.2) Hirschmanniella

(100) 81.5 14.5 (22.4)

a Figures in parentheses indicate angular value = 15.3 at LSD (0.05).

of coleoptiles and plumules. Reduced viability due to nematode pathogens was due to mechanical injury and penetration of pathogens into root tissues, which caused rapid mortality in germinating

Integrated pest management— other pest

c 2 n' i = k + i-1

i × R × n' i-1

Table 2. Frequency distribution of selected genera of plant parasitic nematodes on rice in eastern India.

seedlings. We found that Pratylenchus and M. graminicola accounted for 7-18%

Type and no. Meloidogyne Hoplolaimus Pratylenchus Hirschmanniella of the nematode infestation of rice roots of samples by the 4th day after infestation (DAI) and collected Frequency x a Frequency x Frequency x Frequency x up to 40% by the 7th DAI.

Upland rice - year one Frequency of parasitic nematodes in

Soil 61 18 221 16 42 22 94 20 68 the rhizosphere of upland rice in order of Root 54 33 303 20 39 19 148 33 172 prevalence were genera Meloidogyne,

Pratylenchus, Hirschmanniella, and Hoplolaimus; in rainfed lowland rice, Upland rice - year two

Soil 43 33 304 36 69 25 87 30 120 Root 38 30 408 30 111 24 263 25 20 Hirschmanniella, Pratylenchus,

Rainfed lowland rice - year one Meloidogyne, and Hoplolaimus (Table 2).

Soil 35 13 118 14 86 18 49 30 116 Root 42 21 279 11 195 7 198 32 479

Soil 44 14 33 9 114 8 82 28 332 Root 44 29 212 27 373 26 388 20 622

Rainfed lowland rice - year two

a x = larval and adult population/100 g soil or 1 g fresh weight of root tissue.

from 1988 to 1992 in fixed plots laid out These cropping systems produced in randomized block design. Intensity of

tillers, panicle lengths, and test weights the crop rotations ranged from 200 to Effect of preceding crops on significantly higher rice yield, effective

rice yield than the other systems (see table). 400%.

M. S. Sidhu, R. K. Sharma, and S. Singh, Agronomy Department, Punjab Agricultural University, Ludhiana 141004, Punjab, India

Rice was planted on about 2 million ha in the Punjab State, India, in 1991-92. Rice usually follows nonrice crops. We evaluated the yield and yield attributes of rice grown after crops of wheat, winter maize, field pea - green gram, Swede rape - green gram, potato - transplanted winter maize, Indian rape - transplanted Swede rape - green gram, potato - sunflower, and Indian rape - sunflower

Soil of the experimental field was calcareous, sandy loam with pH 8.1 and 0.28% organic C. All crops received the recommended fertilizer package and practices except sunflower after potato, which was grown without applied fertilizers.

Mean grain yield of rice following wheat was lowest at 4.8 t/ha. Maximum rice yield of 6.5 t/ha was obtained in potato - transplanted winter maize - rice sequence, although it was at par with rice yield from Swede rape - green gram - rice and potato - sunflower - rice systems.

Winter maize - rice, field pea - green gram - rice, Indian rape - transplanted Swede rape - green gram - rice, and Indian rape - sunflower - rice systems all produced about 5.2 t rice/ha.

Farmers can obtain higher rice productivity by selecting suitable preceding cropping systems, such as potato - transplanted winter maize, Swede rape - green gram, and potato - sunflower. These systems can also help improve soil fertility and contribute to crop diversification.

Effect of preceding crops on yield attributes and grain yield of rice. Punjab, India, 1988-92.

Grain yield (t/ha) Preceding crops

Effective Panicle 200-grain tillers/ length weight

1988-89 1989-90 1990-91 1991-92 Mean plant (no.) (cm) (g)

Wheat 5.0 5.9 5.6 3.4 4.8 8.5 22.4 Winter maize

5.25

Field pea - green gram 5.6 6.0 5.2 3.9 5.2 8.1 22.8 5.25 Swede rape - green gram 6.6 7.1 6.6 5.2 6.2 9.5 23.7 5.50 Potato - transplanted winter maize 6.8 7.4 6.6 5.9 6.5 9.6 23.7 5.75 Indian rape - transplanted Swede rape -

Potato - sunflower 5.50

6.5 7.0 6.3 6.0 6.2 9.6 23.9 6.00 Indian rape - sunflower 3.7 7.0 5.5 4.7 5.2 8.2

LSD (0.05) 0.6 22.7 5.25

0.3 0.8 0.9 0.6 0.8 1.2 0.60

5.4 6.2 5.7 3.7 5.2 8.6 23.0 5.25

green gram 4.0 6.9 5.4 4.8 5.2 8.8 22.2


Farming system

Socioeconomic impact Impact of modern mangrove swamp rice varieties in Sierra Leone and Guinea A. A. Adesina and M. Zinnah, West Africa Rice Development Association (WARDA), 01 B.P. 2551, Bouake, Côte d’lvoire

Guinea and Sierra Leone account for 46% of the total cultivated area of mangrove swamp rice in West Africa. WARDA and Sierra Leone Rice Research Station started a major rice improvement program in 1976 that targets about 200,000 ha of mangrove swamps cultivated to rice in the region. Several modem varieties (MVs), including ROK5, ROK10, Kuatik Kundur, and CP4, have been developed for and diffused across mangrove swamp rice ecologies.

We studied diffusion and adoption patterns and economic benefits of these varieties for smallholder farmers in the principal mangrove swamp rice areas in Guinea (Coyah Region) and Sierra Leone (Great Scarcies Region).

Farmers ranked the 10 most important mangrove swamp rice varieties that they grow. Based on frequency of farmers in Sierra Leone growing the varieties, ROK5 was ranked 3d, ROK10 5th, and Kuatik Kundur 7th. In Guinea, ROK5 was the only MV of any importance. Farmers ranked it as the 5th most important variety grown.

adopting at least one of these MVs increased from 5% in 1986 to 52% in 1990. In Guinea, adoption of MVs was a more recent phenomenon: in 1989, only 1% had adopted a MV; in 1990, 17% had (see figure). In Sierra Leone, 11% of total mangrove rice area was planted to MVs in 1988 and 21% in 1990. In Guinea, rice area under MVs increased from 2% in 1989 to 9% in 1990. Mean share of total rice area under MVs in the two counties rose from 9% in 1988 to 16% in 1990.

Farmers’ perceptions of specific varietal characteristics of MVs, including ease of cooking, ease of threshing, tillering capacity, and yield, determine adoption behavior. Results run contrary to widely accepted views in the adoption-diffusion

In Sierra Leone, percentage of farmers


Adoption and impact of improved rice varieties: regional impacts in the Coyah Region of Guinea and the Great Scarcles Region of Sierra Leone, 1986-90.

Item 1986 1987 1988 1989 1990

Share of total mangrove rice area in improved varieties (rate of adoption) (%) Guinea 2 9 Sierra Leone 4 5 11 18 21

Farm-level impact (US$ million) Guinea 0.06 Sierra Leone 0.92 1.2 2.5 4.2 4.9

0.3

Share of income from mangrove rice coming from improved varieties (%) Guinea 0 0 0 3 13 Sierra Leone 6 7 16 25 28

Cumulative impact (1 986-90) (US$ million)

Guinea 0.36 Sierra Leone 13.7

Total 14.1

Cultivation of improved swamp rice varieties in Guinea and Sierra Leone, 1986-90.

literature that it is farmer and farm-specific

Cumulative farm-level economic impact adoption behavior of farmers. costs when adopting MVs. or institutional factors that condition rare, so farmers had no additional variable

Economic impact of MVs was studied of MVs (see table) was estimated to be at farm level in villages and at the regional US$14 million in the Great Scarcies Region level. Farm-level economic benefits were from 1986 to 1990, and $0.4 million in computed using data on incremental

economic benefits since 1990). Future changes in area under MVs, average yield Coyah Region (which mainly captures

the possibility of even greater adoption. fertilizers and herbicides, was extremely countries during the past several years and cash inputs to produce MVs, such as increase in farmers growing MVs in both area under MVs, and rice price. Use of increase substantially given the dramatic varieties, farm households’ cultivated rice economic impact of MVs in Guinea should differences between MVs and local

- - -

- - -

Research methodology Lyophilized blast (BI) fungal laboratory restricts exchange of fungal mycelia are nonviable and suitable for international

isolates.

exchange Purified DNA is currently the only

accepted material for international exchange among rice-growing regions.

R. Scott, B. Consignado, R. Nelson, and R. Zeigler, IRRI; and H. Leung, Plant

We determined that freeze-dried hyphae of

Pathology Department, Washington State B1 fungus are nonviable and can be safely

University, USA exchanged instead of pure DNA. We tested the viability of intact lyophilized mycelia

In the study of populations of rice B1 (84 samples) and ground lyophilized fungus Magnaporthe grisea (anamorph mycelia (58 samples) from different field Pyricularia grisea, P. oryzae), DNA strains of M. grisea. Hyphal plugs of fingerprinting based on restriction M. grisea were started and grown on fragment length polymorphism (RFLP) modified Fries medium (per liter: 30 g and randomly amplified polymorphic sucrose, 5 g ammonium tartrate, 1 g DNA (RAPD) has proved highly NH 4 NO 3 , 1 g KH 2 PO 4 , 0.5 g MgSO 4 , 0.1 g informative. Plant pathologists studying B1 recognize the need to analyze

CaCl 2 , 0.1 g NaCl, 0.5 g yeast extract, and

lyophilized. Dried mycelia were pul- of M. grisea into the region of the host rinsed with sterile distilled water, and about introducing nonindigenous strains

Mycelia were harvested by suction, solution to limited resources, concern prevent conidiation. fungal populations seems the ideal tinuously submerged and agitated to equipped laboratories for comparison of about 150 rpm. Mycelia were con- assays. While collaboration with well- (28-30 °C) on a rotary platform moving at resources to perform RFLP and RAPD shaken for a week at ambient temperature few institutions have the necessary Erlenmeyer flasks. Flask cultures were and worldwide. Unfortunately, relatively 50-ml volumes in 125- or 250-ml populations of the fungus both regionally 0.5 g casein hydrolysate) dispensed in

verized manually under liquid nitrogen. Both intact and ground mycelia were then inoculated onto Fries medium and prune agar plate (per liter of prune infusion: 30-40 g prunes, 5 g lactose, 1 g yeast extract, and 20 g agar), and observed for fungal growth. None of the lyophilized mycelia incubated on either medium for 5 d at 30 °C initiated B1 fungal growth.

We conclude that freeze-dried fungal mycelia are nonviable and therefore suitable for international exchange. For shipment, we recommend that mycelia be packed individually in sterile coin packets and sealed collectively in evacuated plastic bags with activated silica gel or any suitable solid desiccant. Mycelial powders should be wrapped in greased or weighing sheets prior to packing in coin packets to avoid cross-contamination. If kept moisture-tight, mycelia can be stored and shipped at ambient temperatures for at least a week. For long-term storage, we suggest shelving samples at subzero temperatures. Blast researchers for whom DNA extraction is impractical should find the possibility of exchanging lyophilized mycelia particularly useful.

An empirical relationship between N input and false smut intensity in rice Harkirat S. Dhindsa, Biological Science Department, Faculty of Health Sciences, The University of Sydney, Lidcome, New South Wales 2141, Australia; and Harjinder S. Dhindsa, Regional Rice Research Station (RRRS) Kapurthala, Punjab, India

A strong correlation between N input and false smut ( Claviceps oryzae-sativae ) incidence has consistently been reported in the literature. An empirical model that quantitatively describes this relationship might assist in predicting the disease.

We conducted an experiment at RRRS, Punjab Agriculture University, Gudaspur, Punjab, to characterize this relationship. Data were recorded for rice cultivars PR109 and PR106, which were transplanted in 5- × 2-m plots. The experiment

Table 1. Observed (Obs) and predicted (Pred) percent incidence of false smut, RRRS, Punjab Agricultural University, Gurdaspur, Punjab, India.

Plants Tillers Grains Cultivar Nitrogen

(kg/ha) Obs Pred Obs Pred Obs Pred

PR109 29 92

154 217 279

E R 2

P

PR106 29 92

154 217 279

E R 2

P

11.4 16.2 22.9 30.5 36.2

8.6 14.3 18.1 23.8 30.5

11.1 16.9 23.1 29.6 36.6

0.027 0.996

<0.01

8.9 13.4 18.5 24.1 30.3

0.035 0.996

<0.01

14.9 15.9 1.4 22.7 20.9 3.3 29.3 28.6 4.2 36.3 39.0 4.7 53.4 52.1 5.8

0.060 0.984

<0.01

12.8 12.8 1.3 19.3 19.3 2.0 24.8 24.9 2.5 29.6 29.6 2.9 33.5 33.5 3.2

0.002 1.0

<0.01

1.5 3.0 4.2 5.0 5.6

0.065 0.977

<0.01

1.3 2.0 2.5 2.9 3.2

0.006 1.0

<0.01


Table 2. E values for five functions.

PR109 PR106 Function

Plants Tillers Grains Plants Tillers Grains

Lesion length of rice ShB in detached leaf test. Guangzhou, China, 1991.

Lesion length (mm) a

Bacterial isolate Antagonism Inhibition of to lesion

infection extension

12542 0 a 1.3 a Rh71 0 a 2.5 a RH72 1.7 a 41.0 c Jinggangmycin b 2.3 a 4.2 ab RH62 4.3 a 2.7 a 11541 7.5 a 24.1 bc RH921 9.7 a 9.5 ab RH715 11.7 a 6.0 ab RH121 15.8 a 8.5 ab RH22 16.5 a 0.5 a RH92 17.2 a 6.8 ab RH131 43.2 b 4.3 ab 9642 45.7 bc 11.0 ab RH76 51.8 bc 9.2 ab Check 57.7 bc 30.7 c 8343 67.2 c 39.8 c a Results reported are based on two experiments where each treatment was replicated three times. In a column, means followed by a common letter are not significantly different at 5% level by DMRT. b Antibiotic made in China.

isolates obtained through this rapid screening method reflect biological control ability in the field. Our next step is to test selected isolates in the greenhouse and field to confirm their effectiveness as biological control agents.

Damping-off incidence, assessed as percent diseased mungbean plants, was measured 5 d after inoculation. Eighteen of the 288 antagonistic isolates tested reduced damping-off incidence to 50% of that of the control and were considered effective.

The ability of these 18 isolates to protect rice leaves from R. solani infection and to restrict lesion expansion was verified with the detached-leaf technique (Rosales et al 1993). Antagonism to infection was tested by spraying rice leaves with bacterial suspension and then placing mycelia discs of R. solani on each leaf. Inhibition of lesion expansion was tested by infecting rice leaves with R. solani and then spraying bacterial suspension on leaves. We conducted the two experiments in randomized complete block design. Each treatment was replicated three times. Inoculated leaves were incubated in moist chambers at 28-30°C. Lesion length was measured 5 d after applying the bacteria.

Ten of the 18 isolates protected rice leaves from infection, and 11 inhibited ability to inhibit lesion expansion (see table). Further evaluation is needed if

y = mx+c e y = ax b

y = ab x

y = ax b

y = ax 2 + bx + c

0.041 0.185 0.052 0.097 0.027

0.085 0.201 0.050 0.110 0.060

0.156 0.054 0.202 0.056 0.065

0.035 0.163 0.071 0.073 0.035

0.039 0.082 0.081 0.030 0.002

0.051 0.063 0.087 0.018 0.006

was laid out in a split-plot design with three replications. Five levels of N were the main plots and cultivars the subplots.

Soil had 29 kg available N/ha, 1.2 kg available P/ha, and 45 kg available K/ha. To compensate for P deficiency and to maintain N levels of 29, 92, 154, 217, and 279 kg/ha, 25 kg P/ha and one-third of the N were applied before puddling. The remaining N was applied equally at 3 and 6 wk after transplanting.

We randomly selected three 1-m 2

areas in each plot at crop maturity and recorded disease incidence. Percentage of infected plants, tillers, and grains in both cultivars were calculated (Table 1).

Five equations (exponentials: e y = ax b , y = ab x , y = ax b , and polynomials) were used to describe the relationship between nitrogen (x) and disease incidence (y). Functions were fit to data using standard error or estimate: E = [(1 /N) S {( (fp - fo)/

fo } 2 ] 1/2 , where fp (predicted) and fo (observed) are data from N measurements.

E was used to compare regression models (Table 2). A threshold of E = 0.1, which corresponds to an average error of 10% between observed and predicted data, was chosen for selecting the relationship. The best fit was obtained with a quadratic function with error variance of 0.02-0.07.

A quadratic function (y = ax 2 + bx + c) was used to predict disease (Table 1). Residuals (9%) were located randomly on both sides of the predicted curve.

For this data set, a quadratic model best described the relationship between N level and false smut intensity. This type of regression model could be used to predict disease incidence provided other conditions match closely. Planners can use these predictions to estimate crop losses.

A rapid method for screening rice-associated bacteria antagonistic to Rhizoctonia solani Lin Birun, Wu Shangzhong, Xu Xianming, Yang Qiyun, and Zeng Liexian, Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, P. O. Box 510640, Guangzhou, China; and T. W. Mew, IRRI

Screening isolates is an important step in developing biological control agents for R. solani, the causal agent of sheath blight (ShB) of rice. We developed a rapid and simple method for screening large numbers of isolates for antagonism to R. solani.

Bacterial isolates were isolated and tested for antagonistic effect on R. solani by dual culture on potato sucrose agar medium. We used 208 bacterial isolates that strongly inhibited in vitro R. solani mycelium growth to determine the effect of seed bacterization. Seeds of mungbean (another host of R. solani ) and R. solani inoculum were spread on sterilized petri dishes. Bacterial suspension was sprayed on each dish. Dishes were kept in a growth chamber.


row × 10 cm deep) were excavated to a depth of 35 cm in four replications. Each monolith was sectioned vertically in five 2-cm-thick segments (see figure). Soil from each segment was washed on a 1-mm mesh screen. Roots were cleaned

and dried at 60°C to constant weight. RMD was calculated as mg roots/cm 3

soil and regressed against horizontal distance (d) from the plant base using a polynomial function. Average RMD (Dˆ) was computed by integrating the polynomial fitted to the horizontal root distribution (RMD f[d]) in the unit soil strip and dividing it by distance between two limits.

Using single-site augering to determine root distribution of rice K. Kumar, O. P. Meelu, Yadvinder-Singh, and Bijay-Singh, Soils Department, Punjab Agricultural University (PAU), Ludhiana 141 004, Punjab, India

Simple auger sampling method is generally used to determine root distribution of field-grown plants. We formulated and tested a method for determining average root mass density (RMD) of rice using single-site sampling (SSS). Root data were obtained from experiments on N and green manure effects on rice in loamy sand and sandy loam soils at PAU Research Farm, Ludhiana. Plots were puddled by disking twice followed by planking in standing water. Six-wk-old rice seedlings of cultivar PR106 were transplanted in mid- June 1992 at 15- × 20-cm spacing.

Roots were sampled by monolith excavation and by auger at 20,40, and 75 d after transplanting (DT). Because rice seedlings were inserted 5 cm below the soil surface during transplanting, the 0-5 cm soil layer contained no roots and was removed before sampling. Soil monoliths (10 cm toward midrow × 15 cm along the

Estimated position for centering the auger and root mean square deviation (RMSD) of root mass density (RMD) for different sampling schemes at different plant growth stages.

Soil Av RMD Estimated RMSD Stage Treatment layer R 2 (D^) position for

(cm) (mg/cm 3 ) centering the Schemes auger (cm) A B C (A+B)/2

Loamy sand 20 DT N (60 kg/ha) 5-15 0.88* b

N (120 kg/ha) 5-15 0.93* GM a 5-15 0.91*

40 DT N (60 kg/ha) 5-15 0.98*

N (120 kg/ha) 5-15 0.99* 15-25 0.67*

GM 5-15 0.98* 15-25 0.82*

75 DT N (60 kg/ha) 5-15 0.91* 15-25 0.58 25-35 0.90*

N (120 kg/ha) 5-15 0.99* 15-25 0.36 25-35 0.93*

GM 5-15 0.99* 15-25 0.97* 25-35 0.93*

15-25 0.42

0.22 0.22 0.32 0.38 0.05 0.90 0.03 0.65 0.07 0.61 0.08 0.03 1.09 0.08 0.04 1.27 0.13 0.06

3.1 0.79 0.47 3.5 0.50 0.24 3.6 0.35 0.28 3.5 0.27 0.44 3.0 0.30 0.10 3.5 0.34 0.22 3.8 0.30 0.04 3.4 0.25 0.32 4.0 0.10 0.12 3.1 0.32 0.74 3.5 0.15 0.21 3.2 0.10 0.15 3.5 0.49 0.50 3.0 0.19 0.17 3.6 0.05 0.08 3.4 0.45 0.38 3.0 0.15 0.08 3.7 0.11 0.05

0.12 0.04 0.09 0.11 0.03 0.15 0.05 0.13 0.02 0.15 0.05 0.07 0.10 0.08 0.08 0.08 0.17 0.08

0.11 0.05 0.10 0.10 0.04 0.12 0.07 0.14 0.02 0.10 0.09 0.04 0.12 0.10 0.04 0.04 0.13 0.10

Sandy loam 20 DT N (60 kg/ha) 5-15 0.97* 0.26

N (120 kg/ha) 5-15 0.98* 0.28 GM 5-15 0.97* 0.30

40 DT N (60 kg/ha) 5-15 0.98* 0.49 15-25 0.81* 0.07

N (120 kg/ha) 515 0.99* 0.94 15-25 0.82* 0.09

GM 5-15 0.92* 0.74 15-25 0.81* 0.14

75 DT N (60 kg/ha) 5-15 0.90* 0.70 15-25 0.58 0.18

N (120 kg/ha) 5-15 0.99* 1.28

25-35 0.99* 0.08 GM 5-15 0.97* 1.29

15-25 0.98* 0.25 25-35 0.98* 0.09

25-35 0.90* 0.13

15-25 0.82* 0.18

a GM = green manure. b * = significant at P = 0.05.

3.3 0.85 0.69 0.13 0.11 3.4 0.43 0.09 0.10 0.11 3.4 0.10 0.13 0.09 0.07 3.5 0.43 0.51 0.18 0.21 4.0 0.11 0.19 0.10 0.15 3.5 0.33 0.27 0.13 0.07 4.0 0.14 0.17 0.11 0.07 3.5 0.65 0.35 0.13 0.14 3.2 0.08 0.05 0.05 0.03 3.1 0.71 0.33 0.15 0.11 3.7 0.33 0.21 0.10 0.05 3.0 0.12 0.11 0.09 0.07 3.6 0.59 0.41 0.09 0.09 3.2 0.10 0.11 0.05 0.04 3.3 0.05 0.10 0.05 0.05 3.4 0.55 0.28 0.16 0.12 3.5 0.19 0.15 0.05 0.07 3.2 0.12 0.10 0.04 0.07

Sampling schemes for monolith excavations and single-site augering. a


a* = plant

D Ù = 1/10 0 ò 10 RMD f(d)

The Dˆ in each layer and treatment was interpolated on the horizontal root distribution curve to determine the center for single-site augering (see table). For a given soil layer, RMD determined by centering a 5-cm-diam auger using this sampling scheme (C in figure) was compared with other possible single-site sampling schemes (A and B in figure). Auger samples were collected from nine replications for all schemes. Reliability of a sampling scheme was assessed from root mean square of differences in RMD with the given scheme from Dˆ.

RMD was greatest close to the plant base and decreased with increasing distance to a point. Then RMD increased again due to contribution of roots from

the adjacent row. RMD distribution for all treatments and stages followed the same pattern. A quadratic polynomial generally best explained the relationship between horizontal root distribution and distance.

The position for centering the auger for SSS, computed from interpolation of Dˆ on the horizontal root distribution curve, was between 3 and 4 cm from the plant box for both soils irrespective of sampling stage and treatment (see table).

When compared with other SSS methods, RMD determination using scheme C resulted in minimum root mean square deviation (RMSD) from Dˆ. RMSD of scheme (A + B)/2 was comparable with scheme C, but sampling

at two sites requires more labor and time and is highly destructive.

Results suggest the horizontal root distribution in the top 10-cm soil layer may be sufficient for determining the sampling site for centering the auger. In puddled and flooded soils, a small ring should be hammered around the sampling site a day before sampling and the water removed from within.

Single-site augering estimates of RMD are very close to those of monolith excavations. The simplicity and precision of the single-site auger method allows more replications and rapidity of sampling-with reduced labor and destruction of experimental plots—than do other methods.

News about research collaboration IRRI guidelines encourage marketing of hybrid rice seed to farmers Farmers in developing countries will pay for hybrid rice seed-if it benefits them at harvest.

A policy statement by the IRRI Board of Trustees makes all breeding lines, elite germplasm, and parental lines produced by the Institute’s breeding program freely available to both public and private organizations. IRRI’s hybrid rice materials will be provided to national agricultural research systems for their use and for sharing with private organizations in their countries.

“IRRI recognizes that the private sector is likely to play an important role in developing hybrid rice technology,” says S. S. Virmani, an IRRI plant breeder who specializes in hybrid rice. “To expedite the process of getting hybrid rice seed to farmers, IRRI realized the need to have guidelines to govern the distribution of IRRI hybrid materials.”

property protection (patents) for its rice breeding materials. IRRI expects recognition, however for the use of its materials when a hybrid rice variety is released.

The Institute will not seek intellectual

Virmani believes that the value-added institutions and private benefits of hybrid rice-just like hybrid

that a) the material is not intended maize and cotton-will make the organizations on the understanding

organization, b) IRRI retains the seed companies. for exclusive use by any single technology attractive to both farmers and

IRRI’s policy on intellectual property right to distribute the same material rights and hybrid rice is as follows: to other organizations, and c) the

IRRI adheres to the policy of free use of IRRI materials will be availability of breeding lines, elite

produced in its breeding program variety is released. germplasm, and parental lines recognized when a hybrid rice

organizations for the development and will not seek intellectual Collaboration with profit-making

property protection on these of hybrid rice technology will materials. proceed after consultation, where IRRI will provide hybrid rice appropriate, with the authorities in parental lines (and other elite the respective host country. materials) to both public sector

Thai farmers like mechanized harvesting system Farmers in northeastern Thailand may soon be harvesting their rice faster— with fewer workers and less expense.

increasing costs to farmers in some Asian countries. At the same time, rice prices are declining. IRRI agricultural engineers have been developing efficient mechanized rice harvesting systems for small farms to reduce harvest costs.

Researchers from IRRI and the Agricultural Engineering Division of the

Serious labor shortages at harvest are

Thai Department of Agriculture field- tested the IRRI-designed stripper gatherer harvesting system on small farms near Khon Kaen. The farmers liked the machine’s maneuverability. Its 80-cm working width efficiently harvested both lodged and erect rice on small plots; farmers agreed that the grain loss was acceptably low.

“Farmers were most impressed by the machine’s ability to harvest and thresh simultaneously,” says Boru Douthwaite, a consultant in the IRRI Agricultural Engineering Division. Farmers have been suffering severe grain losses due to


threshing delays of up to a month. The machine weighs only 190 kg, so

workers can transport it over canals and to out-of-the-way fields where large combines cannot go. Local manufacturers are interested in producing the machine, which costs about US$1,600.

New center for rice research in Iran The Agricultural Research, Education, and Extension Organization of Iran has established a Rice Research Institute to concentrate on the country’s second most important cereal crop. It is located at Rasht, Gilan Province, and Seyyed-Ali Elahinia is the manager. Until now, rice research was divided among several of

Potassium deficiency potentially linked with disease problems in Vietnam Heavy outbreaks of sheath blight, blast, and some previously unknown rice diseases are plaguing farmers in the intensively cultivated lowlands of Vietnam. Many farmers are using fungicides in futile attempts to restore plant health.

On-farm experiments indicate these rice plants are severely deficient in potassium, making them highly vulnerable to diseases. If this finding is confirmed, it will have important implications for sustainable yield increases and productivity of rice in the intensively cropped lowlands.

The Overseas Development Administration-funded project was conducted by IRRI in collaboration with the Silsoe Research Institute of the United Kingdom.

Iran’s discipline-oriented research institutions.

Agricultural and Natural Resources Research Organization and IRRI. This collaboration includes rice germplasm exchange and improvement, degree and nondegree training, and participation of Iranian scientists in IRRI conferences, workshops, and networks.

Elahinia is the liaison between Iran’s

Vietnam’s cropping intensity is perhaps the highest in Asia-one reason why the country is the world’s third largest rice exporter.

Scientists of the Plant Protection Research Institute and the University of Cantho in Vietnam are studying the problem with IRRI researchers. They are focusing on the relationship between rice plant nutrition and disease development. They want to know whether nutrient deficiencies or imbalances actually contribute to disease severity.

If their research is successful, it will provide Vietnamese rice farmers with an integrated crop management strategy that reduces rice disease problems and the need for fungicides. The research project is funded by the Australian International Development Assistance Bureau.

China’s hybridization program benefits from INGER Participation in International Network for Genetic Evaluation of Rice (INGER) activities has accelerated China’s efforts in rice research and hybridization during the past 14 years. China now boasts of more than 13 million ha of riceland devoted to the direct use of INGER materials for production and for its expanding rice hybridization program.

“With the test materials from INGER, parental sources for rice breeding in China have been greatly enriched,” says Xiong Shenmin, director of the China National Rice Research Institute (CNRRI). Breeders at CNRRI have used INGER material Milyang 46 of South Korea to develop hybrid rices Shanyou 10, Xieyou 46.11-You 46, and D-You 46. Shanyou 10 was planted to more than 400,000 ha of riceland in 1991. It is expected to become the most commonly planted late-season hybrid rice in the country at about 800,000 ha.

Breeders from the Lixiahe Institute of Agricultural Sciences in Jiangsu Province used BG90-2 of Sri Lanka to develop varieties Yangdao 1 and Yangdao 2. Breeders at Nanjing Agricultural University used BG90-2 as a parent source to derive Nannongshon—a variety highly resistant to bacterial leaf blight and rice blast and moderately resistant to rice planthoppers. The Jiangsu Academy of Agricultural Science has developed Ya-You 2, an indica/ japonica hybrid rice. One of its parents originated from BG90-2/IR2F.

Weedy forms of rice present in Southeast Asia Rice farmers in Southeast Asia are experiencing more weed problems, a result of their shifting from transplanting seedlings to the more efficient direct seeding. Wild Oryza species and weedy forms of rice are the greatest threat as they mimic cultivated rice, according to Keith Moody, IRRI weed specialist. He found weedy rice in farmers’ fields in June in Malaysia and the Philippines. Up to now, this problem had been confined to Europe and the Americas.

Weedy rices are difficult to control because they look like cultivated varieties and have the same response to herbicides. Planting contaminated seed is a major cause of the problem. Once an area is infested, the weedy rices easily spread. They can cause major damage to the quantity and quality of farmers’ rice harvest.

Moody recommends an integrated control approach, combining preventive, cultural, and chemical methods. He urges farmers to use certified seed or seed that is clean and of good quality. Crop rota-

tion and good water management are important, too.

Researchers of national agricultural research systems and IRRI will be collaborating, Moody reports, to identify contaminated areas, assess yield and quality losses, and develop control strategies. Without this research, Moody predicts weed control costs will increase and, as a result, many farmers will switch to other enterprises or abandon valuable rice-producing lands that are needed to feed Asia’s rapidly increasing population.


Chinese provincial researchers to be trained by IRRI IRRI is joining with the Ministry of Agriculture of China to train its provincial-level staff to conduct on-farm adaptive research. The goal of the World Bank-funded project, according to E. L. Matheny, head of the IRRI Training Center, is to carry out on-farm trials that demonstrate farming recommendations

specific to China’s prefectures and counties.

Fifty researchers from 10 provinces will be trained in the Philippines by IRRI; they will then share this knowledge with prefecture- and country-level agronomists in their provinces.

The Training Center has designed a special 4-month course that emphasizes farming systems research methodologies and basic training skills. The training will be in two sessions, the first began in July

and the second will be in early 1994, each for 25 researchers. Two postdoctoral fellows from the Chinese Academy of Agricultural Sciences will be part of the training team.

95, IRRI specialists will assist the provincial staff members in organizing and implementing adaptive research training. They will use IRRI training materials that have been modified and translated into Chinese.

In the project’s second phase in 1994-

Announcements Postdoctoral research fellowships at IRRI The International Rice Research Institute invites applicants for postdoctoral research fellowships in the following fields: Plant breeding. Identification of genes controlling root system development in rice. The work involves developing a

A candidate must have a recent Ph D in soil science, soil microbiology, environmental sciences or related discipline and be from a rice-growing country in Asia. Experience in gas chromatography is required. Experience in computer modeling or use of computer models, data base management, and

statistics is desirable. The two-year position is available immediately.

Send letter outlining research experience, knowledge of analytical methodologies, curriculum vitae, and at least two letters of recommendation to H.-U. Neue, Head, Soil and Water Sciences Division, IRRI.

marker-aided selection scheme for deep roots, collaborating in studies on root

Rice dateline morphology of cultivars adapted to drought-prone environments, and assisting in screening of breeding materials.

IRRI and at the drought resistance screening site in Ubon, Thailand. A working knowledge of Thai language will be helpful.

Send curriculum vita, university transcripts, and three letters of recommendation to S. Sarkarung, Plant Breeder, IRRI Cooperative Project with the Ministry of Agriculture and Cooperatives, P.O. Box 9-159 BKN, Bangkhen, Bangkok 10900, Thailand. Fax: (66-2) 561 -4894. E-mail: 157:CG1405.

Soil science—ethane emission. Investigation of mechanisms governing production, oxidation, and fluxes of methane emission from ricefields through laboratory, greenhouse, and field research. Assist in analysis and evaluation of ongoing field and laboratory experiments on trace gas emission.

The research will be conducted at

10 Jan- International Course on Computer 4 Feb Applications in Irrigation,

Southampton, UK .................................................... Course Administrator Effective Irrigation

Management Short Courses Institute of Irrigation Studies

The University, Southampton S09 5NH, UK

24-26 Jan Third Workshop on Rice Supply and Demand Project, Bangkok, Thailand .......................................................... M. Hossain, IRRI

25-26 Jan 11th Training Course on Photosynthesis and Productivity in a Changing Environment, Bangkok, Thailand .......................................................................... D. Hall

Division of Life Science Kings College, University of London

Campden Hill Road, London, W8 7AH, UK

10-11 Feb PhilRice-IRRI Work Plan Meeting, IRRI ................................................... G. L. Denning/F. A. Bernardo, IRRI

21-22 Feb First International Workshop on Rice Research Prioritization, IRRI ................................................................................ M. Hossain, IRRI


21-24 Feb

28 Feb- 5 Mar

28 Feb- 5 Mar

6-9 Mar

14-15 Mar

14-18 Mar

21-22 Mar

21-25 Mar

Temperate Rice-Achievements and Potential, Yanco Agricultural Institute, Yanco, New South Wales, Australia .................................... Conference Convenor

Temperate Rice-Achievements and Potential NSW Agriculture, P.O. Box 1490

Griffith NSW 2680, Australia

Rainfed Lowland Rice Thematic Conference and Steering Committee Meeting, India ................................................................................... R. Zeigler, IRRI

Physiology and Biochemistry of Tolerance for Drought and Submergence, Lucknow, India ............................................................... V. P. Singh, IRRI

25th Meeting of the Rice Technical Working Group, New Orleans, Louisiana USA ............................................... S. Linscombe

P. O. Box 1429 Crowley, LA 70527-1429, USA

Thailand-IRRI Work Plan Meeting, Bangkok, Thailand ....................................... D. Puckridge/G. L. Denning/

F. A. Bernardo, IRRI Climate Change and Rice Symposium, IRRI ................................................................. S. Peng/B.S. Vergara, IRRI

Global Change Impact on Agriculture and Forestry, Rice Ecosystem Workshop, IRRI ................................................................................... M. Kropff, IRRI

9th International Rice Conference for Latin America and the Caribbean and 5th National Rice Research Meeting of Brazil Goiania, Goias, Brazil ............................................ B. de Silveira Pinheiro

EMBRAPA/CNPAF Caixa Postal 179

7400 Goiania, GO, Brazil

Send in your nomination for Outstanding Young Women in Rice Science Awards Time is ticking away! Nominations for the 1994 Outstanding Young Women in Rice Science Awards must be received at IRRI by 1 Feb 1994. Established in 1990, these recognitions encourage greater participation of women in rice research and promote their professional improvement. DANIDA, the Danish International Development Agency, is funding the 1994 program.

years of age or younger (born on 1 Jan 1954 or later) and actively conducting research in any endeavor of rice science in a public or private institution located in the five regions of the developing world’s rice-producing areas. Recipients are selected by regions: Africa, South Asia, West Asia, Southeast Asia, and Latin America and the Caribbean. Awards are made without regard to race, color, religion, national origin, or political persuasion of nominees.

Each nomination must be submitted by the head of the employing research institution or agency. It must be in English and include a description of the individual’s research work and previous accomplishments (not to exceed 1,000 words).

nied by

The awards are for women who are 40

Each nomination must be accompa-

two of the individual’s published papers or technical reports issued between 1989 and 1992, a curriculum vita or biodata statement and a certification of birth date (with English translation if needed), five copies of a current photograph, black-and-white or color, suitable for publication (minimum size: 2 × 2 inches or 5 × 5 cm), and

references to support the nomination.

The selection committee appointed by

recommendations from three

the IRRI director general will evaluate the nominations and choose the 1994 awardees. Their selections will be based on the originality and relevance of the


nominee’s rice research and the scientifi- cally rigorous manner in which it has been conducted. The decisions of the committee are final, and no award will be made for any region in which the nominees fail to demonstrate excellence in rice research.

All nominations and supporting materials must be received by IRRI by

5:00 p.m., 1 Feb 1994. Incomplete submissions are not acceptable. Nomina- tions should be sent to the Chairperson, Outstanding Young Women in Rice Science Awards, c/o Information Center, IRRI.

when received, will become the property of IRRI, and will not be returned.

All nominations will be acknowledged

For further information about the program and procedures, send a letter to the address above or fax (63-2) 818- 2087.

IRRI group training courses for 1994

IRRI will conduct 14 short-term group training courses during 1994.

IRRI provides a limited number of scholarships for participation in these courses. To be considered for an IRRI- funded scholarship, a scientist must be affiliated with a national institution that has an official collaborative agreement with IRRI in rice-related research and training projects. Scientists interested in an IRRI-funded scholarship should apply directly to his or her institution and not to IRRI.

IRRI also accepts scientists from other institutions and agencies for the courses if they are working in rice or rice-related areas. Their applications to participate in courses must be endorsed to IRRI by their employer and specify a funding source to cover costs. IRRI’s

Date Course

21 Feb-1 Apr

21 Mar-15 Apr 25 Apr-3 Jun 6 Jun- 1 Jul 18 Jul-9 Sep

25 Jul-16 Sep

10 Oct-2 Dec 3 Oct-4 Nov

17 Oct-4 Nov 17 Oct-11 NoV 31 Oct-11 NoV 7 Nov-2 Dec

14-25 NoV 14-25 NoV

Irrigation and Water Management

Hybrid Rice Seed Production Engineering for Rice Agriculture Training on Video Production Integrated Pest Management (University of the Philippines

Integrated Nutrient Management Rice Seed Health Rice Production Research (Pathum Thani Rice Research

Upland Rice Breeding Geographic Information Systems Scientific Programming Simulation and Systems Analysis for Rice Production

Gender Analysis Research Management

(Kasetsart University, Thailand)

at Los Baños/National Crop Protection Center/PhilRice)

Center, Thailand)

(SARP)

group course training fee is approx-

For additional information, contact the include participants’ roundtrip headquarters unless otherwise indicated. imately US$1,200/month; this does not

The courses are conducted at IRRI

international airfare, enroute expenses, or Head, Training Center, IRRI. shipping allowance upon return home.

Climate Change and Rice Symposium An international symposium on climate change and rice will be held at IRRI on 14-18 Mar 1994 to review the broad issues of global climate change and its effect on agriculture. The symposium will be a forum to summarize research on the specific impact of climate change on rice and rice ecosystems.

Twenty-seven invited speakers will present papers on production and emission of trace gases by rice soils and the effects of UV-B, CO 2 , and temperature on rice. Other participants are encouraged to present posters on these topics.

Vergara, Climate Change and Rice Symposium, IRRI.

For details, contact S. Peng or B. S.


~

Wet seeded rice workshop

IRRI will host a workshop on Constraints, Opportunities, and Innovations for Wet Seeded Rice on 24-27 May 1994 in Bangkok, Thailand. Discussion topics will include environmental characterization, germplasm evaluation, input use efficiency (water, nutrients, labor), pest management (weeds, diseases, insects,

25th Meeting of the Rice Technical Working Group The 25th Meeting of the Rice Technical Working Group will be in New Orleans, Louisiana, USA, on 6-9 Mar 1994. People interested in submitting papers should note this schedule:

snails), and social and environmental implications.

Workshop goals are to exchange information, assess technology for different environments, determine research priorities, and develop a work plan.

Scientists involved in wet seeded rice research are encouraged to attend the workshop. Send requests for details to K. Moody, APPA Division, IRRI.

Abstracts must be received by 1 Feb 1994. Interpretative summary will be included in the program. Submit only two papers for presentation as senior author, indicating which is the oral and which is the poster presentation.

Individuals submitting only one paper must present it orally.

For more details, contact Steve Linscombe, Local Arrangements Chairman, P.O. Box 1429, Crowley, Louisiana 70527-1429, USA. Tel: 318- 788-7531. Fax: 318-788-7553.

McNamara Fellowship Program

The Robert McNamara Fellowship Program awards 10 fellowships to support innovative and imaginative postgraduate research in areas of

equivalent at time of application, must carry out the research work under the auspices of an adviser in the host institution of choice in a World Bank- member country, and must have a working knowledge of the language spoken in the country where he or she

economic development. Each fellowship will carry out the research. covers a 12-month period normally

Program, Room M-4029, World Bank Criteria for fellowship eligibility: must

Send applications and correspondence Temperate rice conference beginning 1 Jul and ending 30 Jun. to the Robert S. McNamara Fellowship

A technical conference, Temperate be a national of a World Bank-member

Agricultural Institute, Yanco, New South be held 21-24 Feb 1994 at the Yanco must have at least a master's degree or

Washington, D.C. 20433, USA. Rice—Achievements and Potential, will country, be not more that 35 years old, Headquarters, 18 18 H. Street, N.W.,

Wales, Australia. The McCaughey Memorial Institute is the sponsor. Themes are breeding and genetics, quality, storage and processing, rice agronomy and management, crop protection, economics and marketing, environment and sustainability, and extension and education.

Conference Convenor, Temperate Rice— Achievements and Potential, NSW Agriculture, P.O. Box 1490, Griffith NSW 2680, Australia.

For more information, contact the

New IRRI publications 1992 Program report

Rice in human nutrition

Pesticides, rice productivity, and farmer's health: an economic assessment

1993-1995 IRRI rice almanac

Rice literature update reprint service

New publications Agricultural policy and sustainability: case studies from India, Chile, the Philippines, and the United States. Published by World Resources Institute (WRI).

Biodiversity prospecting: using genetic resources for sustainable development. Published by WRI, USA; Instituto Nacional de Biodiversidad, Costa Rica; Rainforest Alliance, USA; and African Centre for Technology Studies, Kenya.

Rice conference for Latin America and the Caribbean

Photocopies of items listed in the Rice Order from WRI Publications, literature update are available from the P.O. Box 4852, Hampden Station, IRRI Library and Documentation Service. Baltimore, MD 2 12 11, USA.

The 9th International Rice Conference for Reprints of original documents (not to Latin America and the Caribbean and the exceed 40 pages) are supplied free to rice 5th National Rice Research Meeting of scientists of developing countries. Rice Brazil will be held in Goiania, Goias, scientists elsewhere are charged US$0.20 Brazil 21-25 Mar 1994. They are jointly

Genetic Evaluation of Rice (INGER) for orders payable to Library and plus postage. Make checks or money sponsored by the International Network for for each page or part of a page copied,

CNPAF) of Brazil. Center for Rice and Beans (EMBRAPA/ Address requests to Library and Latin America and the National Research Documentation Service, IRRI.

productivity of rice in the region are to be

Documentation Service, IRRI. E-mail: Alternative methods for increasing IN%“[email protected]”

analyzed. Topics for discussion include genetic improvement and commercial achievement of biological yield potential, cropping systems for efficient use of available resources, diversification of uses and markets to increase consumption, and organization of research to integrate public and private resources.

For more details, contact Beatriz de Silveira Pinheiro, EMBRAPA/CNPAF, Caixa Postal 179,7400 Goiania, GO, Brazil. Tel: (5562) 261-3022. Fax: (5562) 261-3880.

Call for news Individuals, institutions, and organizations are invited to tell readers about upcoming events in rice research or related fields in the Rice dateline. Send announcements to the Editor, International Rice Research Notes, IRRI.

Fertilisers, organic manures, recyclable wastes, and biofertilisers. Management of nutrient interactions in agriculture. Fertiliser management in food crops. Methods of analysis of soils, plants, waters, and fertilisers. Edited by H.L.S. Tandon. To order, contact Fertiliser

Development and Consultation Organisation, 204 Bhanot Comer, 1-2 Pamposh Enclave, New Delhi 110048, India. Fax: 91-11-6862196.

Man-made lowlands. History of water management and land reclamation in the Netherlands. Edited by G.P. Van der Ven. Send orders to Uitgeverij Matrijs, P.O.

Box 670, NL-3500 AR Utrecht, The Netherlands.


IRRI address International Rice Research Institute P.O. Box 933 Manila 1099 Philippines Tel: (63-2) 818-1926 Fax: (63-2) 818-2087 Telex: (ITT) 40890 RICE PM E-mail: IN% “postmaster@ IRRI.CGNET.COM”

Errata Efficiency of natural selection against cold-induced sterility in bulked families, by J. P. Tilquin and J. F. Detry, 18 (1) March 1993, 33.

In figure, read F 6 , F 7 , and F 8 ; in text, read “were subjected to natural selection in F 4-8 ” and “F 6-8 , trials showed sterility levels below that of Ambalalava.”

Comparative efficiency of Sesbania, Gliricidia, and urea as N sources in wetland rice, by Kundu et al, 18 (3) (Sep 1993), 27.

with 3.4. In column 6 of the table, replace 7.4

Combined effects of pests in farmers’ fields: methodological outlines of a yield- loss data base in rice, by N. P. Castilla et al, 18 (3) (Sep 1993), 41-42. A simple methodology for analyzing rice sheath blight (ShB) epidemiologic processes under semicontrolled conditions, by R. M. Leaño et al, 18 (3) (Sep 1993), 42.

In both notes, S. Savary’s affiliation was incorrectly printed. It should be IRRI-Institut Français de Recherche Scientifique pour le Développement en Cooptration (ORSTOM).


Instructions for contributors

NOTES

General criteria. Scientific notes submitted to the IRRN for possible publication must • be original work, • have international or pan- national relevance, • be conducted during the immediate past three years or be work in progress, • have rice environment relevance, • advance rice knowledge, • use appropriate research design and data collection methodology, • report pertinent, adequate data, • apply appropriate statistical analysis, and • reach supportable conclusions.

Routine research. Reports of screening trials of varieties, fertilizer, cropping methods, and other routine observations using standard methodologies to establish local recommendations are not accepted. Examples are single-season, single-trial field experiments. All field trials should be repeated across more than one season, in multiple seasons, or in more than one location as appropriate. All experiments should include replications and an internationally known check or control treatment.

Multiple submissions. Normally, only one report for a single experiment will be accepted. Two or more items about the same work submitted at the same time will be returned for merging. Submit- ting at different times multiple notes from the same experiment is highly inappropriate. Detection will result in the rejection of all submissions on that research.

IRRN categories. Specify the category in which the note being submitted should appear. Write the category in the upper right-hand corner of the first page of the note.

GERMPLASM IMPROVEMENT genetic resources genetics breeding methods yield potential grain quality pest resistance

diseases insects other pests

stress tolerance drought excess water adverse temperature adverse soils other stresses

integrated germplasm improvement

irrigated rainfed lowland upland deepwater tidal wetlands

seed technology

CROP AND RESOURCE MANAGEMENT

soils soil microbiology physiology and plant nutrition fertilizer management

inorganic sources organic sources

crop management integrated pest management

diseases insects weeds other pests

water management farming systems farm machinery postharvest technology economic analysis

ENVIRONMENT SOCIOECONOMIC IMPACT EDUCATION AND COMMUNI-

RESEARCH METHODOLOGY CATION

Manuscript preparation. Arrange the note as a brief statement of research objectives, a short description of project design, and a succinct discussion of results. Relate results to the objectives. Do not include abstracts. Do not cite references or include a bibliog- raphy. Restrain acknowledg- ments.

Manuscripts must be in English. Limit each note to no more than two pages of double- spaced typewritten text. Submit the original manuscript and a duplicate, each with a clear copy of all tables and figures. Authors should retain a copy of the note and of all tables and figures.

Apply these rules, as appropriate, in the note: • Specify the rice production ecosystems as irrigated, rainfed lowland, upland, deepwater, and tidal wetlands. • Indicate the type of rice culture (transplanted, wet seeded, dry seeded). • If local terms for seasons are used, define them by characteristic weather (wet season, dry season, monsoon) and by months. • Use standard, internationally recognized terms to describe rice plant parts, growth stages, and management practices. Do not use local names. • Provide genetic background for new varieties or breeding lines. • For soil nutrient studies, include a standard soil profile description, classification, and relevant soil properties. • Provide scientific names for diseases, insects, weeds, and crop plants. Do not use common names or local names alone. • Quantify survey data, such as infection percentage, degree of severity, and sampling base. • When evaluating susceptibil- ity, resistance, and tolerance, report the actual quantification

of damage due to stress, which was used to assess level or incidence. Specify the measurements used. • Use generic names, not trade names, for all chemicals. • Use international measurements. Do not use local units of measure. Express yield data in metric tons per hectare (t/ha) for field studies and in grams per pot (g/pot) for small-scale studies. • Express all economic data in terms of the US$. Do not use local monetary units. Economic information should be pre- sented at the exchange rate US$:local currency at the time data were collected • When using acronyms or abbreviations, write the name in full on first mention, followed by the acronym or abbreviation in parentheses. Use the abbreviation thereafter. • Define any nonstandard abbreviations or symbols used in tables or figures in a footnote, caption, or legend.

Tables and figures. Each note can have no more than two tables and/or figures (graphs, illustrations, or photos). All tables and figures must be referred to in the text; they should be grouped at the end of the note, each on a separate page. Tables and figures must have clear titles that adequately explain the contents.

Review of notes. The IRRN editor will send an acknowledg- ment card when a note is received. An IRRI scientist, selected by the editor, reviews each note. Reviewer names are not disclosed. Depending on the reviewer's report, a note will be accepted for publication, rejected, or returned to the author(s) for revision.

(continued on back cover)

Documents

International Rice Research Notes Vol.18 No.4