National Cooperative Testing · The National Cooperative Testing Project for rice (NCT) was started in 1954 by the Bureau of Plant Industry (BPI), University of the Philippines College

National Cooperative Testing Manual for Rice

Guidelines and Policies

RICE TECHNICAL WORKING GROUP National Seed Industry Council

Department of Agriculture

Foreword

Rice breeding aims to develop varieties that are high-yielding, resistant to pests and diseases, have good grain quality, and well adapted to the different rice growing ecosystems in our country. It takes 5 years to develop promising rice lines. It takes another 2-3 years to test them in multi-location yield trials before they are recommended for release as new varieties. From here on, the seeds of these new varieties are increased from breeder seeds to certified seeds before the farmer will finally be able to avail of them. Furthermore, it may take another 2 years before a new variety will become popularly or widely planted. In total, it takes about ten years from conception to popularization of a variety (Figure 1). Selected parents based on the desired characters in the progeny are crossed during hybridization (pollination). The female parent is first emasculated by removing the anthers (pollen) and then pollinated by the male parent. The F1 progenies are then planted and initial selection is done in the F2 population. A series of selections in succeeding generations is done until a homogenous population is attained. The popular variety, Burdagol, was developed by a farmer in Mindanao through pure line selection. The farmer apparently made this selection from the field and developed a homogenous population from that selection. Burdagol was then entered in the NCT pipeline and proved equal to or better than existing commercial varieties. Burdagol was approved as PSB Rc34. Pure line selection method was also used with traditional Philippine varieties like PSB Rc16 (Ennano), PSB Rc36 (Ma-ayon), PSB Rc38 (Rinara), PSB Rc40 (Chayong) and PSB Rc3 (Ginilingan Puti). From the different accessions and types of these traditional varieties, the most promising were selected and entered in the NCT. The development of new varieties is now being hastened with the employment of biotechnology tools. Genetic engineering and marker-aided selection are now being fine-tuned as tools in the rice breeding program. These should cut down the development time of promising lines by about 2 years. Biotechnology also enables the incorporation of new or exogenous genes needed to improve the performance of the rice plant. The last stages of evaluation before a promising line is recommended for release as commercial variety are conducted in the National Cooperative Test (NCT). The promising line is tested nationwide in comparison with prevalent commercial varieties as check varieties. Its yield performance, pest and disease resistance, and grain quality are assessed in the NCT. The Rice Technical Working Group (RTWG) evaluated the results of the NCT and identifies the most promising lines during their semi-annual and annual meetings. These lines are submitted to the Technical Secretariat of the National Seed Industry Council (NSIC) which in turn recommends to the NSIC for approval as new variety. Santiago R. Obien Executive Director

Policies And Guidelines for NCT of Rice The National Cooperative Testing Project for rice (NCT) was started in 1954 by the Bureau of Plant Industry (BPI), University of the Philippines College of Agriculture (UPCA), and the Bureau of Agricultural Extension (BAEX) as nationally conducted cooperative trial for rice varietal improvement. It is a continuation of the concerned agencies efforts to develop new and improved rice varieties for the Philippines. Initially, the NCT conducted yield trials for lowland and upland rices in five to eight locations. The objective was to determine the relative merits of several varieties in the different regions of the country. It was also aimed at reducing the number of varieties for propagation and distribution to each region (Torres and Hernaez, 1956) Presently, the NCT is implemented by the Rice Technical Working Group (RTWG). The RTWG is a technical working group of the National Seed Industry Council (NSIC) mandated under the Seed Industry Development Act of 1993 (RA 7308) to: (1) conduct field testing and performance evaluation of promising rice lines and hybrids, and nominate to the NSIC new improved rice varieties for cultivation (2) formulate procedures for varietal evaluation and identification; and (3) perform other related functions that may be assigned to it by the Executive Director of NSIC.

Agencies involved The members of the RTWG come from the participating agencies/entities in the NCT. These include researchers from the primary rice breeding institutions in the Philippines namely: (1) Philippine Rice Research Institute (PhilRice) of the Department of Agriculture (DA), (2) the University of the Philippines at Los Baňos (UPLB), and (3) the International Rice Research Institute (IRRI). The other members of the RTWG come from the BPI and other DA stations, selected Agricultural Colleges and Universities (ACUs), Philippine Nuclear Research Institute (PNRI) and some private individuals or agricultural corporations.

Organization The RTWG is headed by a chairman and the NCT is orchestrated by a National Coordinator. There are five coordinators representing each of the following areas of concern: Advanced Yield Test, Disease Resistance Test, Insect Resistance Test, Grain Quality Evaluation and Environmental Stress Evaluation. Researchers of government and private agencies/institutions involved in rice breeding or field testing may join the RTWG upon the recommendation of their respective agencies and upon the approval of the majority of the members of the group present in the RTWG midyear or annual meeting. The group shall meet regularly in April and November of each year. Special meetings may be called by NSIC or by the chairman or majority of the RTWG coordinators. In the regular meetings, results of the various tests conducted in the preceding season will be discussed. Selections for nominations to the Technical Secretariat of NSIC for naming and release of varieties, if there are any, as well as those selections for seed increase, will be decided upon during the meeting. Other matters relating to rice varietal development, testing, seed production and distribution, recommendations, and financial support will also be discussed. The RTWG nominates promising lines to the Technical Secretariat of the NSIC. The Technical Secretariat deliberates on the nominations and recommends for approval to the Council promising line as a commercial variety (Figure 1).

Entries for Testing Entries for testing come from the participating entities in the RTWG. Testing of entries entered by profit-oriented private companies will be covered by a separate Memorandum of Agreement. Entries may be pure lines, hybrids or multilines. These shall be accompanied by essential information such as the original source of varieties, parents and cross combination, type of pollen control (hybrids), filial generation, preliminary yield trial data from sponsoring agency, disease and insect pest reactions, number of days from sowing to heading and plant height. The RTWG shall determine the check cultivars and entries to be accepted for testing. Variety checks for grain quality should be grown along with the advanced test in selected locations. Promising selections in advanced tests or those recommended for seed increase shall be the entries in on-farm adaptation trials.

Number of entries Entries shall be classified according to their intended agro-ecological environments (eco-system) such as irrigated-lowland (transplanted and direct seeded); drought prone or flood prone rainfed-lowland; saline prone; upland; and cool elevated (rice terraces) areas. In addition, there shall also be separate groups for hybrid rice and special purpose rice. In irrigated lowland, entries shall be grouped according to maturity and method of crop establishment. There can be one or more check varieties or each group. The maximum number of entries for each environment-maturity group is summarized in Table I. Grain quality evaluation of all entries shall be conducted regularly in UPLB, and Phil-Rice-Maligaya. However, in other places in the country, this will be done whenever necessary. Entries in “rice terraces” group shall also be evaluated whenever necessary. Grain quality evaluation shall be the responsibility of PhilRice and UPLB.

Test Locations Tests should be conducted in the various major rice producing areas in the country. Sites for advanced yield trials are given in Table 2.

Calendar of Activities The following timetable shall be followed to meet the required activities.

Season

ACTIVITY

Dispatching Of Seed

Planting Harvesting Data Submission

Group Meeting

Dry Nov-Dec Dec-Jan Mar-Apr Aug1 Nov

Wet May-June June-July Oct-Nov Jan1 Apr 1 October for data on grain quality 2 February for data on grain quality

The National Coordinator will receive and package the entries and send them along with the planting plans, data and research information sheets, and summary forms to participating stations. The coordinator for the different areas of concern are responsible for consolidation and analyses of data obtained and preparation of reports. The national coordinator/chairman of the RTWG shall coordinate these activities.

Table 1. Maturity and maximum number of entries to be tested under different ecosystem in the advanced yield trials, Phase I and II.

Ecosystem Maturity Maximum Number of Entries

Advanced Yield Trials, Phase I

Irrigated lowland (IL)

Group I <115 15

Group II 116-130 15

Group III >130 15

Hybrid Rice 100-130 15

Drought-prone rainfed lowland (DRL)

Group I

100-130

15

Flood-prone rainfed Lowland (FLR)

Group I

No restriction

15

Saline-prone (S) Group I

No restriction

15

Upland (UL) Group I

No restriction

18

Rice Terraces (RT) RT-I

No restriction

12

Special Purpose Types No restriction 10

Advanced Yield Trials, Phase II

Irrigated lowland (IL)

Group I <115 10

Group II >116 10

Table 2. Sites for advanced yield trials. Irrigated Lowland (Phase I)

PhilRice Maligaya

PhilRice Los Baňos

PhilRice Midsayap

PhilRice San Mateo

BIARC, Pili, Camarines Sur

WESVIARC/CPU, Iloilo City Irrigated Lowland (Phase II)

Libmanan, Camarines Sur

PSU, Sta. Maria, Pangasinan

TCA, Camiling, Tarlac

Abulog Expt. Station, Cagayan

DA-San Luis, Aurora

MinSCAT, Victoria, Or. Mindoro

SPCP, Aborlan, Palawan

PSPC, Mambusai, Capiz

ASCA, Banga, Aklan

PhilRice RTR, Agusan del Norte

CMU, Musuan, Bukidnon

WMSU, Zamboanga City

Bohol APC, Tagbiliran City

UEP, Catarman, Northern Samar

DEBESMAC, Mandaon, Masbate

SSPC, Tandag, Surigao del Sur

WESMIARC, Ipil, Zamboanga del Sur

USM, Kabacan, North Cotabato

DES, Dinagras, Ilocos Norte

MSU, Marawi City Hybrid

PhilRice Maligaya, Muňoz, N.E.

PhilRice San Mateo, Isabela

Hagonoy, Davao del Sur

Sto. Cristo, Gapan, N.E.

B.M. Domingo, Aurora Isabela

SKPSC, Tacurong, Sultan Kudarat

Cargill Phils. Inc., Gen. Santos City

APC-Iguig, Cagayan Upland

Arakan Valley, South Cotabato

WESMIARC, Ipil, Zamboanga del Sur

Tupi, South Cotabato

CMU, Musuan, Bukidnon

MSU, Marawi City

La Granja, La Carlota City

Bohol APC, Ubay, Bohol

Ilagan, Isabela

Gamu, Isabela

Gabaldon, N.E. Rainfed Lowland a. Dry Seeded

MMSU, Batac, Ilocos Norte

BIARC, Pili, Camarines Sur


RES, Babatngon Leyte

Ilagan, Isabela

APC-Iguig, Cagayan

b. Transplanted (DP)

UPLB, College, Laguna


BUNAS, San Idelfonso, Bulacan

CVIARC, Ilagan, Isabela

PhilRice San Mateo, Isabela

PSPC, Mambusao, Capiz

PSU, Sta. Maria, Pangasinan

TCA, Camiling, Tarlac

Saline

Camalaniugan, Cagayan

Calabanga, Camarines Sur

DA-Guiguinto, Bulacan

Libmanan, Camarines Sur

Brgy. Maug, Butuan City

Paranas, Samar

Cold Tolerance BSU, La Trinidad, Benguet DA-Benguet, Tublay

Banaue, Ifugao Tinglayan, Kalinga Bontoc, Mt. Province Lagawe, Ifugao Special Purpose PhilRice Maligaya, Muňoz, N.E. WESVIARC, Hamungaya, Iloilo City Dinagras, Ilocos Norte

Dropping of Entries Dropping of entries will be discussed by the RTWG during its regular meetings.

Dropped entries may be retained for further testing in certain location for regional recommendation.

As a general rule, entries in the irrigated lowland advanced tests with an average

yield of 5 percent lower than the group check (or group mean) for 2 seasons (at 90 kg/N) are dropped from further test. Susceptibility to disease or insect pests, poor grain quality and poor agronomic characteristics are also basis for dropping entries.

Nominations to the National Seed Industry Council A selection may be nominated to the Technical Secretariat of the National Seed Industry Council (NSIC) as a commercial variety or all regions (national recommendations), specific regions of the country (regional or location specific recommendation), and for registration. For national recommendation, a selection must have satisfied a minimum of three advanced yield tests (Table 3) and at least two seasons in Phase II. For regional recommendation, evaluation in at least two locations for at least two seasons within a particular region is needed. Recommendation for rainfed lowland, upland, saline and cool elevated areas are regional in nature, while those for special purpose rices will be for variety registration. A new selection may be nominate to the Technical Secretariat of the NSIC on the basis of superior yield, better agronomic and grain characteristics or higher levels of resistance to diseases and insect over existing varieties. Those with average yield of 10% or higher than the group check or the mean, may be recommended for approval. A selection not distinctly superior than existing varieties may also be recommended for release as a variety if it carries new genes for resistance against the major diseases and pests or has a different genetic background. Sister lines can only be a recommended if they posses superior agronomic characteristics than those previously recommended and belong to different maturity group. Sufficient breeder seeds (50 kg) should be available at the time a selection is recommended for release as variety. Recommended selections should have a narrative description and other information based in nursery tests and field observations such as: grain yield, number of days from sowing to maturity, mature plant height, response to lodging, and reaction to diseases and insects. It should also include grain quality data derived from physical tests, physico-chemical evaluation , cooking parameters and sensory evaluation, and agro-morphological data derived from distinctness, uniformity, stability test (DUST).

Table 3. Minimum number of advanced tests at different locations and seasons

required before an entry can be considered for recommendation.

MINIMUM NUMBER OF TESTS*1

ENVIRONMENT Seasons Season-location combinations Locations Wet Dry W/D

Irrigated lowland a) Phase I b) Phase II

6 2 1 - 18

20 1 1 - 40

Hybrid Rice 6 2 2 - 24

Rainfed lowland a) dry seeded b) transplanted

6 2 - - 12

8 2 - - 16

Saline prone 6 2 2 1 24

Rice Terraces 5 2 2 - 20

Upland 10 2 - - 20

Special purpose rice 4 - - 2 8 *1

This will mean that the selection (s) has been recommended for seed increase, if not then they cannot be recommended as NSIC named variety.

Naming of Varieties All rice varieties recommended to the NSIC shall follow the nomenclature approved by the Philippine Seed Board (PSB) in 1990. Each variety will be coded PSB Rc plus a number (e.g. PSB Rc 50). Irrigated and rainfed lowland varieties will be assigned even numbers; and upland varieties, odd numbers. Furthermore, a local name shall be assigned to each variety. Irrigated-lowland and rainfed lowland varieties will be given popular names of rivers and lakes and upland varieties will be given popular names of mountains. Stop gap varieties will retain their breeding line numbers. Traditional and farmers varieties shall retain their local name.

Seed Production PhilRice shall maintain breeder seeds of all Seed Board approved rice varieties. These breeder seeds shall be increased to foundation seed in quantities adequate to meet the national requirement. Foundation seeds of appropriate varieties will be allocated to different experiment stations, selected member ACUs and qualified seed producers to produce registered seeds. For popularly planted rice varieties, the breeding institution shall maintain at least 50 kg and make it available to PhilRice upon request.

Directions for Conducting Field Performance Tests OBJECTIVES

1. Advanced yield trials, Phrases I and II are conducted to determine the yield potential, range of adaptability and field reactions to major insect pests and diseases of promising rice selections.

2. To identify those that could be considered for national or regional

recommendations.

EXPERIMENTAL SITE, DESIGN AND LAY-OUT A field uniform in soil texture, depth and fertility and more or less representative of the soil type in the area should be chosen for the experiment. The field should have not been used previously for fertilizer or intercropping experiments. Fields for upland trial should be well drained and may be level to slightly sloping. For irrigated-low-land test, adequate irrigation and drainage facilities are necessary. It is suggested that the same area be utilized for advanced tests every season. For irrigated lowland with fertilizer recommendation split plot design will be used. A minimum of 5m2 harvestable area for Maligaya, Los Baňos, Midsayap with recommended size of 3m x 4m. For other trials, a randomized complete block design with at least three replications shall be used. Plot size, number of rows, rat of seeding and distance of planting for advanced and on-farm adaptations tests are given in Table 4.

Table 4. Plot size, number of rows, rate of seeding and distance of planting for advanced yield tests, Phase I and II.

Plot Size

(m) LxW

No. of Rows

1 No. of Hills/

Row or Seed Weight/Row

2

Plant Spacing (cm)3

Between Rows Within Rows

Transplanted

1.Irrigated lowland 3.0x4.0 15 20 20 20

2. Drought and saline 4.0x6.0 20 30 20 20

3. Cool elevated 4.0x6.0 20 30 20 20

Direct seeded

Irrigated Lowland 3.0x4.0 15 g/row

1. Rows are made parallel to the length of the plot. 2. Hills/row and weight/row pertain to transplanted and direct-seeded culture, respectively. 3. Distance between rows is valid only for transplanted culture.

In laying out a trial, a replication should be as square as possible. A 12-entry/18-

entry advanced test should have three replications with two sub-blocks for each replication. A block is equivalent to a replication for a 6-entry advanced test. Sample layouts are shown in Fig. 2, 3, 4, 5, 6, 7, 8 and 9. There should be at least three border rows around each plot. Alleys along labeled plot ends should be at least 0.5 m wide. There should be no vacant rows between entries. In lowland fields, it is important that all plots in a replication be located in the same paddy. A paddy does not have to contain all replications. The following should be observed for all field trials:

a) Draw a field plan showing the location of the plots, alleys and border rows before

planting. b) Number the plots consecutively from the left to right in all replications. c) Place stakes bearing the plot number at the first left-most row of each plot. d) Use labels and indelible ink that can stand the weather for the duration of the crop. e) Label all plots before distributing the seedlings (or seed packets) for planting. f) Check the entries and the plots for any possible mistake before transplanting the

seedlings or sowing the seeds. g) Always remind the planters to plant the selections on designated plots only.

CULTURAL MANAGEMENT PRACTICES Follow the cultural management practices used in the area. It is important that the field should be well-prepared before planting. In transplanted trials, dapog or wetbed seedlings may be used Transplant 10 to 14 day old dapog seedlings at 4-5 seedlings per hill and 25 day old wedbed seedling at 2 to 3 seedlings per hill. Keep some seedlings at the end of the plot near the plot label to replant missing hills. Replant missing hills about one week after transplanting. Do not replant missing segments nor thin plants in dry seeded rice. Fertilizer applications Depending on the soil fertility of a specific location, the following N fertilizer levels will be applied:

a. For NCT Phase I sites at PhilRice Maligaya, PhilRice Los Baňos and PhilRice Midsayap (transplanted/direct seeded).

Two N levels during the dry season – 90 kg N/ha and 150 kg N/ha – only 90 kg N/ha will be applied during the wet season.

Total N rate Days after Transplanting

0 max tillering before PI

90 kg N/ha 45 kg 20 kg 25 kg

150 kg N/ha 85 kg 25 kg 40 kg

1 = time of application of N for the proposed changes are still under consideration 2 = Stage should be defined based in (maturity) the physiological growth stage of the

material.

b. For NCT Phase I sites at PhilRice San Mateo, BIARC and WESVIARC

1 N level (90 kg/ha) applied at basal (45 kg), maximum tillering (20 kg), before panicle initiation (25 kg),

c. For NCT Phase II

One N level (90 kg N) applied at basal (45 kg), maximum tillering (20 kg), before panicle initiation (25 kg),

d. For Hybrid Rice

Two N Levels during the dry season – 90 kg N/ha and 150 kg N/ha – only 90 kg N/ha will be applied during the wet season.

Total N rate Days after Transplanting

0 Max littering Before PI Flowering

90 kg N/ha 20 kg 20 kg 30 kg 20 kg

150 kg N/ha 35 kg 35 kg 45 kg 35 kg

For P and K requirements, basis will be soil analysis.

e. For rainfed, saline, cool elevated, upland, and special purpose rices trials, fertilizer rates of 60-30-30 kg/ha (N2, P5O, K2O) may be applied depending upon local situations. Apply 40 kg N and all P and K at planting and before covering the seeds in the furrows. The remaining N (20 kg) should be applied as top dress about a week before panicle initiation. Where weeds are known to be serious, fertilizer application may be withheld altogether until after the first handweeding.

Water Management In irrigated lowland, shallow water depth should be maintained starting at about

three days after transplanting and gradually increased to 3 to 5 cm until the hard dough stage. During weeding the field may be partially drained.

The field should be saturated and not allowed to dry specially during the

reproductive stage when the crop is most vulnerable to moisture stress. Under rainfed lowland conditions, accumulated water should be retained in the paddy except when it has become too deep.

Weed Control A pre-emergence herbicide may be applied at recommended rate and uniformly in the experimental field two to five days after transplanting to control the weeds. Maintain a shallow water depth of 3 to 5 cm for at least two weeks after applying the herbicide. It is suggested that subsequent weeding be done by hand. If for certain reasons the herbicide failed to control the weeds, rotary weed the field.

Early weed control is important particularly in rainfed lowland and upland trials. Apply liquid Butachlor as pre-emergence herbicide in well saturated soil within three to five days after sowing. While herbicide may be used in rainfed lowland and upland trials manual weeding is preferable. Early weed growth can be checked with the use of wheelhoes passed between the rows. Use dulos or trowel for weeding within the rows. Weeding may start 10 days after seedling emergence. Hoes or tractor-mounted cultivators may be used to weed the alleys and the spaces around the experimental field. Second handweeding may be done a month after seedling emergence. Spot weeding after the last handweeding should be done as often as necessary.

Insect and Rat Control Seedlings in the seedbed should be adequately protected from insect pests by applying systematic insecticides. However, insecticide application in the field should be based on the need and should be regulated to determine the differences in the level of resistance among the entries. Insecticide application will be made only when infestation warrants (See Appendix 2, Guide to Decision Making, Appendix 3 for the appropriate insecticide). To control rats effectively, maintain general cleanliness of the surroundings especially the dikes and irrigation canals in the lowland field. Practice sustained baiting immediately after transplanting using chronic rodenticides (See Appendix 2). The following guide is recommended:

a. Mix the rodenticide with low grade milled rice or “binlid” following strictly the instructions of the manufacturer.

b. Place poisoned baits in suitable containers like bamboo tubes, coconut husks, or

cans designed to prevent the baits from getting wet and from being taken by domestic animals. The baits should be placed in at least five strategic locations for every hectare of rice field.

c. Check baiting stations regularly and replace consumed and moldy baits.

DATA COLLECTION Advanced tests, Phase I. One border row on each side of all plots for all

experiments and two hills or 0.3 m segment at each end of the row for transplanted or direct-seeded trial, respectively. Record data using Forms 1, 2, 3 and 4 (Appendix 4-7).

1. Days from sowing/emergence to heading. The rice crop in a plot is considered

heading when about 50% of the tillers have emerged panicles. 2. Resistance to lodging. Record lodging incidence at heading, two weeks after

heading, two weeks after heading and at maturity using the following:

Numerical Score Qualitative Scale Description

1 Resistant All plants are standing

3 Moderately Resistant

About one-third of the plant population are leaning at an angle of about 30º

5 Intermediate About 50% of the plant population are leaning at an angle of about 45º

7 Moderately Susceptible

More than 50% of the plant population are leaning at an angle of 60º

9 Susceptible All plants are lying on the ground.

Lodging due to the crushing effect of neighboring lodged plants due to typhoon should also be marked so as not to confuse from the inherent character of an entry under normal weather conditions.

3. Number of productive tillers

Irrigated and transplanted rainfed lowland; Count panicle bearing tillers in two 4 – hill samples in two adjacent rows in the plot. The number of productive tillers per hill is taken from the average of eight hills.

Direct seeded rainfed and upland; Count the number if tillers bearing panicles on two one meter sampling area from the different middle rows of the plot. Take the average number of productive tillers of the two samples.

4. Plant height. This is the average of the two samplings measured in centimeters from ground level to the tip of the panicle, excluding awns if any, of the tallest tillers from two representative hill or plants from a plot. Measurements may be taken on hills or sampling areas by counting the number of tillers.

5. Grain yield

Transplanted irrigated lowland and rainfed lowland. Exclude border rows and hills damaged by rats and birds for yield determination. On the other hand, hills affected by diseases and insects are included. All hills immediately adjacent to plants which showed insect or disease damage are harvested for yield. Count the number of hills harvested. Thresh, dry and clean the grains.

Compute corrected plot yield as follows:

Corrected plot = Weight of harvest (g) x No. of possible x MF

Yield (g) No. of hills harvested hills per plot

e.g. The number of possible hills per plot of transplanted irrigated lowland is 600 and of transplanted rainfed lowland is 640. Yield (kg/ha) = Corrected plot x No. of possible hills per plot x 1000g/kg

yield (g) harvested plot area (m2)

Where MF is the moisture factor so that yields would be based on 14 percent moisture. MF for the different moisture contents has been calculated and summarized in Appendix 11. While it is highly desirable that yields be based on 14 percent moisture, MF may be ignored and assumed equal 1,000 in stations where no moisture meter is available, provided the grains are sufficiently dried.

Upland and direct-seeded irrigated lowland. Yield is determined from the plot harvest, excluding border rows and end segments resulting from causes not inherently due to the selection/variety. Vacant segments resulting from insect and disease damage are included in the plot yield determination. Thresh, dry and clean the grains.

The corrected plot yield for upland is calculated as:

Corrected plot = Weight of grains (g) x Total possible x MF

Yield (g) Total length of rows length (m) per harvested (m) plot Hectare yield is computed as for direct seeded irrigated lowland.

Corrected plot = Weight of grains (g) x MF

Yield (g) Total length of rows harvested (m)

6. Disease and insect pest. The disease ratings to be sustained to the coordinator should indicated the screening method used. NCT sites that use the induced method of screening will submit the reaction of the test entries to blast, sheath blight, bacterial leaf blight and tungro (greenhouse or modified field methods) diseases. All sites that rely on the natural occurrence of diseases will submit the field reactions of the test entries to blast (leaf or neck), bacterial blight, bacterial streak, narrow brown leaf spot, brown spot, sheath rot, sheath blight and viral (tungro, grassy stunt and ragged stunt) diseases. The plant pathologist or his assistant in the station will conduct the scoring and the ratings submitted to the coordinator for compilation.

Entries will also be rated for resistance to insect pests like the brown planthopper, green leafhopppers, stemborer, whorl maggots, and other prevalent insects whenever the level of infestation in the field is adequate. As in ratings for diseases, evaluation for insect resistance shall be done by the entomologist or his assistant assigned to the station.

Advanced yield tests, Phase II Yield data are taken in all plants except the border row on each side and 0.3 m segments on both ends of all plots. Thresh and clean the harvest. Weigh and determine the moisture content of the grains on the same day. Yield at 14% moisture content is determined as follows:

Yield (kg/ha) = Plot yield (kg) x 10,000 m2/ha x MF

Effective plot size (m2)

where MF = 100 – Moisture content at harvest 86 In the absence of moisture tester, sundry for 2-3 days then store at room temperature for five days before weighing. Record the number of days from sowing/emergence to harvesting for transplanted/direct-seeded rice. The rice crop is considered mature if at least 80% of the grains are yellow. Resistance to lodging, plant height and reactions to diseases and insect pests shall be determined as in advanced tests, Phase I.

OTHER CONSIDERATIONS FOR TRIALS IN SALINE-PRONE AREAS The degree of salinity of the test site will be determined every week starting at transplanting. Separate analysis will be made for soil and soil water. Three samples per paddy will be taken. Soil salinity test kits will be provided by the Department of Soil Science, UPLB-CA. Test procedure is as follows:

1. Soil analysis. Mix 2g of soil and 2ml of distilled water. Allow to stand still until clear solution is observed. Obtain 5 drops of soil water and follow the procedure for soil analysis.

2. Conductivity meter – where available, the conductivity meter will be used in monitoring soil salinity. Pull the seedlings a day before transplanting and keep it in the seedbed (non-saline) areas.

OTHER CONSIDERATIONS FOR TRIALS IN COOL ELEVATED AREAS Recording the atmospheric and water temperatures during the various crop growth stages helps interprete the temperature effects to the test entries and provide a temperature profile of the test site. Meteorological data available at any PAGASA station nearest to the test site can also be integrated in the report. If not available fill in the following temperature/growth form by checking the appropriate category of temperature on a general basis.

TEMPERATURE/GROWTH FORM

Location:

Growth stage Mean Temperature

Low 18ºC or below

Medium 19-24ºC

High 25ºC or above

Seedling

Tillering

Flowering

Maturity

OTHER CONSIDERATIONS FOR TRIALS IN DROUGHT-PRONE RAINFED LOWLAND AREAS The interpretation of data from rainfed lowland trials is highly dependent on the surface hydrology. A simple set of instruments can enable the researcher to record the pattern of water adequacy on the surface and in the upper soil profile over the growing season. The periods of drought or flooding can then be determined and the trial can be classified as drought-prone or favorable.

1. Monitoring water table. Water table is determined using a piezometer made of a 5-cm diameter polyvinylchloride (PVC) tube. There are three piezometers varying in length to be installed. The length of each tube is: 1-45 cm, 2-65 cm and 3-105 cm. Each tube has slits or openings for water passage. A cloth is wrapped around the area with openings and at the bottom to exclude mud during installation.

Tubes are installed in the field using a 5-cm diameter soil auger1 to bore holes to the desired depth (Fig. 10). Tubes may be in the alley at the middle location in the field trial. The top of the tube must be covered to keep out rainwater and dirt (Fig. 11). The water table is measured three times a week with a dip stick (Fig. 12). The observer blows gently into the tygon surface and reading is taken to determine the distance to the top of the tube. The water table depth is the difference between the tube length and reading obtained.

2. Monitoring water depth. Depth of standing water is measured with a bamboo stake marked at 1 cm intervals (Fig. 13). The bamboo stake is installed together with the tubes.

3. Monitoring daily rainfall. If it is possible, daily rainfall should be recorded. 4. Summary of data. All data should be entered in a field hydrological monitoring form

(Table 5). Data to be entered in each column are: Plot the hydrograph as shown in Fig. 14. When standing water is present on the surface, plot the water level as the reading of the bamboo stake. Plot the water depth only during periods when the surface has drained. Water table depth readings may not be accurate when paddy has standing water, so water table depth readings are the most significant when standing water is not present.

Column 1 : Date on which data are taken Column 2 : Rainfall for the date in mm (recorder the following morning) Column 3 : Weekly sum of rainfall Column 4 : Water level in the paddy. Height of water above the ground

surface in cm Column 5 : Soil moisture score 1 – flooded, standing water 3 – no standing water but soil saturated 5 – soil is drained but moist 7 – surface is dry but soil below the upper 2 cm is moist 9 – surface dry and dusty down to 5 cm or more; wide cracks in heavy soils 6-8 – water table depth. Level of standing water in the observation well below the top of the tube is recorded in the upper left hand corner of the box. The level of standing water below the soil Record data for yield and other agronomic characteristics and field reactions to insect pests and diseases.

Experiment:_______________________________ Field location no.: __________________________ Month: __________________________________ Researcher: ______________________________

Rainfall Water Table Depth (cm) Tensiometer reading (cm)

Date

Daily

Weekly Total

Water Level (cm)

Soil Moisture

Score

20cm

40cm

80cm

10cm

20cm

40cm

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Table 5. Field hydrological monitoring form

Screening for Resistance to Major Rice Diseases

INTRODUCTION One way of minimizing crop loss is the use of improved varieties with resistance to major diseases. Unlike other methods of controlling diseases, it is most simple and economical approach. More over, it can be combined with other control methods with minimal detrimental impact on the environment. Screening for disease resistance is a continuing process and its success depends on the presence of the pathogen in abundance and the environmental conditions favorable for the development of the disease. The relative resistance of a plant is its maximum pathologic response to a pathogen. This is evaluated comparatively with a known susceptible check whose principal function is to detect the presence of the disease. The true limit of disease reaction is not frequently attained when one or more factors are not operating in its optimum conditions favoring disease development. In this case, the plant’s true response is poorer than what is presumed. The result: instability of the presumed resistance. Hence, favorable condition for the disease development is a must in the screening for disease resistance.

SCREENING METHODOLOGIES Effective screening methods are essential in breeding for disease resistance. They should be simple to fit local environmental condition and efficient so that screening would not be slow and expensive. The causal organisms can be introduced artificially (induced method) to the test plants or the test plants are naturally infected (natural method) under field conditions. The latter can be applied whenever disease pressures are adequate to give consistent results. Blast, sheath blight, bacterial blight, and tungro are important rice diseases that are endemic in most rice growing regions of the Philippines. They also occur in endemic proportion and causes considerable damage. Since these diseases do not occur at high level in some cropping seasons, intervention in the screening method in some NCT sites is made to favor disease development. This simulates a condition similar to an epidemic outbreak. In all sites however, the natural occurrence and spread of the disease take its course under low to moderate level of infection. Thus, two sets of data will be generated following these methods of screening.

SCREENING PROCEDURES AND EVALUATION FOR RESISTANCE TO MAJOR RICE DISEASES

I. INDUCED METHOD A. BLAST (Pyricularia grisea)

Steps Key points

1. Select area Select an upland field. If a lowland site is used, it should be about 1 ft above the water level, especially during the wet season.

2. Prepare land Plow and harrow the field to make the soil particles

fine. Prepare 1.2 m x 15-20 m 3. Apply fertilizer Before seeding, apply 50-100 kg N/ha and other

nutrients, if necessary 4. Prepare spreader rows Plant 3 spreader rows of the local S-ck variety

around the test plots 2-3 weeks before sowing the test seeds.

5. Seed the test plot Sow 10 g seed/entry in a 50 cm row. Rows are

spaced 10 cm. For every 10 rows of test entry, assign 1 row for the standard S-ck (IR72), 1 row of R-ck, and 1 row of the local S-ck (Fig. 15)

Cover the seeds with fine soil. 6. Manage the nursery Weed and apply insecticides when needed. Water the plants frequently to increase humidity. 7. Introduce Inoculum Collect blast infected leaves, chop to 2 – 5 cm long

and broadcast over the border rows 15 days after establishment

If pure culture is available, inoculate by spraying.

(Inoculum production and inoculation procedure or blast screening is presented in Fig. 16).

8. Evaluate Score at 30-35 days after sowing or when

susceptible checks are severely infected using the 1-9 standard scale below.

Symptoms: On leaves spots are elliptical with more r less pointed ends (spindle shaped), brown borders and grey center. Spots coalesce and the leaf dries. Scale Description

1 None to small brown specks of pinhead size 2 Larger brown specks 3 Small, roundish, necrotic gray spots about 1-2 mm in diameter

with brown margin 4 Lesion is elliptical, 1-2 cm long usually confined to the area of the

two main vein, average of one to five lesions on a leaf 5 Average of six to ten lesions on a leaf or less than 10% of leaf

area infected. 6 Average of 11-25% leaf area infected 7 Average of 26-50% leaf area infected 8 Average of 51-75% leaf area infected 9 Average of above 75% leaf area infected

Index 1 - Scale 1, 2, and 3 Resistant Index 2 - Scale 4. 5 and 6 Intermediate Index 3 - Scale 7, 8 and 9 Susceptible

Note: This scale is used only for nursery tests.

B. SHEATH BLIGHT (Rhizoctonia solani)

Steps Key points

1. Prepare test plants Sow seeds in wetbed nursery. Transplant 20-25

day-old seedlings at 2-3 seedlings per hill in rows of 8-10 hills, spaced 20 cm x 25 cm. Each row is

assigned a test entry. Every ten rows of test entries, assign 1 row of

standard S-ck (IR20) and 1 row of the susceptible local check.

2. Manage plots Follow the recommended fertilization for wet and

dry seasons. 3. Prepare inoculum Culture the causal organism on sterilized rice grain

and rice hull mixture (1:3) and incubate at room temperature for 2-3 weeks (Fig. 17).

4. Inoculate Inoculate each entry at 45-50 days after

transplanting by placing about one teaspoon of the cultured organism in between tillers.

5. Evaluate Score at 23 weeks after inoculation using the 1-9

standard scale below.

Symptoms: Spots or lesions occur on leaf sheaths and may extend to the leafblades. They

are grayish green, oval or elliptical and coalesce mostly on the lower leaf sheath. Lesion becomes grayish white with brown margins.

Scale base on relative lesion height

1 Lesion limited to lower ¼ of leaf sheath area 3 Lesions present at the lower ½ of leaf sheath area 5 Lesions present on more than ½ of leaf sheath area. Slight infection on

upper leaves. 7 Lesions present on more than ¾ of the leaf sheath. Severe infection on

upper leaves. 9 Lesions reaching top of tillers severe infection on all leaves and some

plants died. Index 1 - Scale 1, 3 Resistant Index 2 - Scale 5 Intermediate Index 3 - Scale 7,9 Susceptible

C. BACTERIAL BLIGHT – Xanthomonas oryzae pv. Oryzae

Steps Key points

1. Prepare test plants Follow the procedure in the screening for resistance to sheath blight. However, plant susceptible (IR24) and resistant checks every ten test rows.

2. Manage plots Similar to that of sheath blight screening 3. Prepare inoculum

a. From pure culture Streak 2 loops of 2-3 hour old culture on agar plates (Fig. 18).

Invert and incubate the plates at room temperature

for 49-72 hours.

Pour 10 ml of sterile distilled water on the plate and scrape the bacterial growth.

Prepare 100 ml suspension to have a population of about 108 cells per ml.

b. From infected leaves Collect naturally infected leaves. Remove old

brown lesions and save those with young, advancing lesions.

Cut infected leaves into small pieces. Mix 50 g

infected leaves per 500 ml of water (distilled/rain) and let stand for 20 minutes.

Filter mixture in 2-3 layers of cloth.

4. Inoculate a. With inoculation clippers: Place suspension in the container of the

clipper. Clip the leaves 6 cm from the tip b. With scissors:

Dip the scissors into suspension and cut leaves 6 cm from the tip.

Dip the scissors into the suspension after inoculating each test entry.

5. Evaluate Evaluate at 14 days after inoculation

following the 1-9 standard scale below.

Symptoms: Water-soaked lesions start near the leaf tip and margins, extends downwards, enlarge and turn yellow to gray within days. Scale based on lesions on inoculated leaves.

1 Lesions from cut tip cover 1-5% of the leaf 0-5% lesion are

3 Lesions from cut tip show blight chlorotic symptoms 16-24%

5 Downward length of lesion from cut tip may extend covering ¼ to ½ leaf area showing chlorotic symptoms 25-50%

7 Downward length of lesions from cut tip may extend ¾ of leaf showing chlorotic symptoms 75%

8 Lesions cover > 75% of the leaf and Reaching the leaf sheath 75% Index 1 – Scale 1, 3 Resistant Index 2 – Scale 5 Intermediate Index 3 – Scale 7, 9 Susceptible

D. TUNGRO (Greenhouse screening)

Steps Key points

1. Prepare test plants Sow seeds test entries and susceptible check IR64

at random in a compartment seedbox (Fig. 19) Thin out seedlings into 10-15 per entry 5-6 days

later. 2. Virus acquisition by Collect adult GLH and allow to feed on infected Green leafhoppers plants for 4 days. (GLH) 3. Inoculation Release the viruliferous GLH into the aluminum

screen covered seedbox at 3-4 hoppers per seedling.

4. Transplant inoculated seedlings Remove/retrieve the vectors. Transplant the

inoculated seedlings in lowland plot. 5. Evaluation Evaluate at 3-4 weeks after inoculation and

determine percentage infection.

Symptoms: Stunted plants with mottled and yellow to yellow orange leaves

Percent infection = No. of infected seedlings x 100

Total no. of seedlings Index 1 0 – 20% Resistant Index 2 21%-40% Intermediate Index 3 41%-100% Susceptible

D. TUNGRO (Modified field screening)

In some test sites, susceptible variety and tungro diseased plants are planted in spreader rows to increase disease pressure

Steps Key points

1. Prepare test plot Transplant susceptible variety (IR64) on spreader rows

(Fig. 20). Collect and transplant tungro infected plants within the spreader row. If the station is capable to produce artificially inoculated plants, transplant them I month before sowing the test entries.

2. Prepare test plants Follow the wetbed method of raising seedlings. Transplant test entry in a row of 20 hills spaced 20 x 20 cm at one seedling hill. Plant S-ck (IR64) for every row of test entry.

3. Evaluate Score at 45 and 60 days after transplanting. Evaluate disease reaction by taking the percent infection.

Percent infection = No. of infected plants x 100

Total no. of plants Index 1 0 - 25% Resistant Index 2 26 – 50% Intermediate Index 3 51% - 100% Susceptible

II. NATURAL METHOD

The following diseases would not occur together at a high rate in the field when no intervention is undertaken. Nevertheless the varietal reaction to the following diseases under natural conditions in the field may be evaluated in plants at the center rows at hill 4 to 21 except for sheath blight, sheath rot, and the virus diseases. A. BLAST (Pyricularia grisea)

1. Foliar blast Symptoms: Leaf lesions are spindle-shaped with brown borders and grayish

centers. Evaluation: Evaluate plants at 52-60 days after sowing (DAS) or at growth

stages 3-5 and be taken on first to fourth leaves from base of the plant

Index 1 Small, round of about 1-2 mm in diameter, Resistant gray spots with brown margins; less than 5% leaf area is damaged; present in the leaves of few plants in a plot or population Index 2 Larger, border elliptical lesions with dirty Intermediate white or gray centers; coalesced spots result to about 6-25% of the leaf area damaged; well scattered in the population Index 3 Rapidly expanding lesions resulting to Susceptible 26% or more affected leaf surface; generally present in the whole population 2. Neck rot Symptoms: Dark lesions at the panicle neck. The plant frequently breaks at the point of infection Evaluation Evaluate plants at the center rows at hill 4-21 at 20-25 days after heading or at growth stage 8. Compute perfect infection.

Percent infection = No. of panicles infected x 100

Total no. of panicles Index 1 0 – 5% Resistant Index 2 6 – 25% Intermediate Index 3 26 – 100% Susceptible

B. BACTERIAL BLIGHT (Xanthomonas oryzae) Symptoms: Undulated lesions usually start near the leaf tips or margins

extending downward. Young lesions are light green to grayish green, turning yellow to gray with time.

Evaluation: Evaluate plants at booting to flowering stage or at growth stages

5- 8 on the upper three leaves. Lesion Area Index 1 Yellowing or drying from tip up to Resistant undulated green area does not exceed 5% of the total leaf area. Few plants show symptoms and look greenish in appearance at a distance Index 2 6 – 25% lesion area Intermediate Index 3 26 – 100% lesion area Susceptible C. BACTERIAL STREAK (Xanthomonas oryzicola) Symptoms: Linearly, translucent lesions occasionally with small bead-like bacterial exudates. Evaluation: Evaluate plants at stem elongation to booting stages or at growth stages 4-5. Index 1 None or 1-2 interveinal gray lesions Resistant occurring sporadically or about 5% of the leaf area is infected Index 2 Few to many, 3-6 mm lesions occuring Intermediate on leaf blades; 6-25% of leaf area is damaged. Infected plants are well scattered within the population. Index 3 10 mm or longer lesions covering Susceptible 26% or more. Yellowing and drying of the entire plant population.

D. NARROW BROWN LEAF SPOT (Cercospora janseana)

Symptoms: Linearly, narrow reddish spots parallel to the veins. Evaluation: Evaluate plants at 1-2 weeks before harvesting or at growth stages 6-8 on the upper three leaves. Affected leaf area Index 1 None to few, very narrow but short Resistant reddish brown lesions scattered on leaves; less than 5% leaf area is damaged. Infected plants are sporadically scattered within plant population. Index 2 Numerous larger and longer reddish brown Intermediate lesions on leaves; 6-25% leaf area is damaged; generally scattered within plant population Index 3 Numerous broader, much longer reddish Susceptible brown lesions on leaves, few to many lesions with light brown center, 26-100% leaf area is damaged; generally scattered within plant population. E. BROWN SPOT (Drechslera oryzae)

Symptoms: Spots on leaves are brown, oval, relatively uniform and evenly distributed over the leaf surface. Fully developed spots on glumes have brown or whitish centers. Evaluation: Evaluation is similar to that of narrow brown leaf spot. F. SHEATH ROT (Sarocladium oryzae) Symptoms: Irregular brown spots 0.5 – 1.5 cm long with gray center on the upper most leaf sheath. Rotted young panicles are only partially emerged with numerous empty grains. Evaluation: Evaluate at least 3 hills per plot at the center of the population 3 weeks after flowering or at growth stages 6-8. Compute percent infection.

Percent infection = No. of infected tillers x 100

Total no. of tillers Index 1 0 – 20% Resistant Index 2 21 – 40% Intermediate Index 3 41 – 100% Susceptible

G. SHEATH BLIGHT (Rhizoctonia solani) Symptoms: Grayish green lesion that enlarge and coalesce to form blotches mostly on the sheath. Evaluation: Evaluate 3 hill per plot at the center of the population at least 3 weeks after flowering or at growth stages 6- 8. Compute percent infection.


Total no. of tillers H. VIRUS DISEASES Symptoms: Tungro: Mottled and yellow to yellow orange leaves, stunted growth and slightly reduced tillering. Grassy stunt: Pale green and erect leaves; stunted growth and excessive tillering. Ragged stunt: Ragged or serrated leaves, curled leaf tips, galls or vein swellings on outer surface of leaf sheath; stunted growth; panicles fail to emerge completely. Evaluation: Evaluated all plants at 40-50 DAT and take the percentage infection.


Total no. of tillers Index 1 0 – 30% Resistant Index 2 31 – 60% Intermediate Index 3 61 – 100% Susceptible Check varieties for Natural (Field) Method of Screening. The following varieties will be used as susceptible checks to determine the reaction

of the test varieties to the major rice diseases under the natural (field) screening method:

S-Check var. Diseases IR72 Blast IR20 Sheath blight IR24 Bacterial leaf blight IR64 Tungro These check varieties will be planted in plots 1 m wide (5 hills) and length similar

to the subblocks. They should be randomly distributed at both sides of the test site (as border plots) and should be properly labeled.

Screening for Resistance to Major Insect Pests2

Test for insect resistance will be conducted on all the entries entered in the National Rice Cooperative Testing Project. The primary objective is to characterize and compare the reactions of the different selections to the major insect pests to avoid recommending as commercial varieties those selections which are highly susceptible. In addition to the greenhouse screening and testing in special field nurseries (hot spot areas), the selections will also be evaluated in the field performance test plots. This test will give indication of the reaction of the plant under farmer’s conditions. A minimum of 3 seasons (2 wet and 1 dry) of testing is needed before a selection could be considered as a recommendation to the technical secretariat of the National Seed Council. A. FIELD EVALUATION FOR REGULAR YIELD TRIAL NURSERIES3

1. Brown Planthopper

Rating for brown planthopper resistance in the field trial plots will be based mainly on the degree of hopperburn. Rating will be done on row basis using the middle two rows as sample plots. For the evaluation to be considered valid, the hopper population should be uniformly distributed across the field with at least 10, 25, and 100 hoppers per hill at 10-15 days after transplanting, maximum tillering and early booting stage, respectively. The following rating will be followed using the middle row: Index Rating Description

1 R Slight yellowing of a few plants 3 MR Leaves partially yellow but with no hopperburn 5 I Leaves with pronounced yellowing and some stunting or wilting and 10- 25% of plants with hopperburn, remaining plants severely stunted 7 MS More than half the plants wilting or with hopperburn, remaining plants severely stunted 9 S All plants dead _____________ 2

All damage ratings used are based on the Standard Evaluation System for Rice, 4th

ed., July

1996 3 Ratings of insect pest damage as observed from field performance test plants are to be taken

by the entomologist or his assistant assigned in the station.

2. Stemborers Field rating for rice stemborers will be based on actual percentage deadhearts and whiteheads using the middle row of the plot as sampling area. Deadhearts will be counted 35 and 50 days after transplanting while whiteheads, 10 days before harvest. Or both deadhearths and whiteheads, rating will be based on the following: Index Rating % Deadhearts % Whiteheads 1 R 1 – 10 1 – 5 3 MR 11 – 20 6 – 10 5 I 21 – 30 11 - 15 7 MS 31 – 60 16 - 25 9 S 61 and above 26 and above B. INSECT RESISTANCE FIELD NURSERY TEST Screening for resistance to predominant pest in the locality will be done in the field. In case of brown planthopper or disease outbreak in the nursery, the entries will be rated accordingly using the appropriate scale. Twenty-one-day old seedling will be transplanted one to two plants per hill at 20 cm spacing between hills and rows. Each plot should be 15 hills per row or a total of 45 hills per plot. All recommended cultural practices will be followed except that no insecticides will be applied. The test will be replicated three times. Five rows of susceptible variety (preferably TN 1 and/or IR 8) will be planted as border rows 15 days before transplanting the test entries. To be planted along with the test entries in the inside rows are regular check varieties for stemborer, Rexoro or IR 8 (susceptible check) and TKM 6 (resistant check), and the brownlar check varieties and the brown planthopper biotype differentials will be planted within each maturity group (Figure 21). 1. Stemborers It is advisable to schedule the planting date so as to hit the peak of stemborer population in the locality. Kerosene lamps, fluorescent or incandescent light may be used to attract the moths in the area. Three lights (distributed equally) for each replication should be sufficient. Make the damage rating 35 and 50 days after transplanting. Present deadhearts and whiteheads in susceptible check should average at least 20% and 10% respectively, for the test to be considered valid. However, take reading even if the stemborer damage is less than the above figures. The following 1- 9 scale will be used. Index Rating % Deadhearths % Whiteheads 1 R 1 -10 1 – 5 3 MR 11 – 20 6 – 10 5 I 21 – 30 11 - 15 7 MS 31 – 60 16 - 25 9 S 61 and above 26 and above

Deadearts and whiteheads in the susceptible check should average more than 20% and 10%, respectively, of infested tillers for the test to be considered valid. Percentage deadhearts and whiteheads of susceptible and resistant checks should be recorded. 2. Brown Planthopper This test is done only in case of natural field infestation of BPH. The rating methodology and scale presented in A.1. will be followed. 3. Screening for Black Bugs In case of high field infestation, screening for plants bugs will be done by taking percent damage grains found in 10 panicles randomly selected from within the inner row of the test entries. The following rating scale may be used for the rice bug. Leptocorisa: Index Rating % Damaged Grains 1 R less than 3 3 MR 4 – 7 5 I 8 – 15 7 MS 16 -25 9 S more than 25 4. Screening for Black Bugs For the black bug, the rating scale and sampling scheme for brown planthopper field nursery evaluation (as presented in A. 1.) may be used to separate susceptible from resistant entries.

5. Measuring Tri-Trophic Interaction

Varietal reaction to natural enemies may be measured by actual counts of these beneficials attracted to the test entries using 10 randomly sampled plants within the inner row. Sampling can be facilitated by suction pump samplers (D-Vac or the like). In the absence of samplers, a combination of using sweep net (10 sweeps/entry) and tapping can be used. Insects are later sorted in the laboratory and expressed in mean number per plant.

Tri-tropic measurement can be done concurrent with stemborer damage

assessment.

C. INSECT RESISTANCE SCREENHOUSE NURSERY TEST

1. Maintenance of Hopper Cultures

Test insects must be purified from the progeny of a single female and the initial population characterized using differential varieties to establish biotypes. At least 20% of the colony should be used for sustaining the mass production and the rest are used in various tests. Strengthening of the cultures should be done every after 10 to 12 generations (every 1 ½ to 2 years of continuous rearing) by introducing wild population into the pure culture following standard procedure for purifying field collected insects. Host plants can either be TN 1/IR or any local variety found susceptible to the hoppers in the locality.

2. Screening of Test Entries a) Brown Planthopper

Seedling test for resistance to the brown planthopper will be conducted inside the greenhouse. About 30 seeds of each entry will be directly sown on a compartment seedbox filled with garden soil. The seedbox will be divided into two columns with each column to be further subdivided into 13 rows so that there will be a total of 26 rows in each seedbox. The two middle rows will be assigned to the resistant (IR 26 for biotype 1, IR 36 for biotype 2 and Mudgo for biotype 3) and susceptible (TN 1 for all biotypes) check varieties. Third instar nymphs for the brown planthopper will be introduced uniformly in the seedboxes when the seedlings are 7 days old at a rate to three to five nymphs per seedling. Seedboxes will be kept half-submerged in water to keep the seedlings growing and the environment humid when the susceptible check is completely wilted or killed using the following: Index Rating Description of Damage 1 R Very slight damage

3 MR First and 2nd leaves of most plants partially yellowing 5 I Pronounced yellowing and stunting or about 10 to 2% of the plants wilting 7 MS More than half of the plants wilting or dead and remaining plants severely stunted or dying 9 S All plants dead

b) Green Leafhopper (GLH)

Test materials will be directly sown in a compartment seedbox filled with garden soil. The two middle rows will be assigned to the susceptible TN 1) and resistant (IR 5491) checks. Seedlings at one-leaf stage (about 7 days after sowing) will be uniformly infested with second or third instar non-viruliferous nymphs per seedling. The seedboxes will be kept half – submerged in water to maintain high humidity as well as protect the seedboxes from ants. Rating for resistance will be done in 10 days after infestation when the susceptible check is completely killed. Damage rating will be done using the following grading scale: Index Rating Description of Damage

1 R Very slight damage 3 MR First and 2nd leaves yellowing

5 I All leaves yellow; pronounced stunting or both 7 MS More than half of the plants dead;

remaining plants wilting; severely stunted 9 S All plants dead

Grain Quality Evaluation INTRODUCTION The development of numerous modern rice varieties provide more choices to farmers, traders, millers, processors as well as household consumers who in turn become more selective. As a result, one of the thrusts of the breeding program is geared towards the availability of good quality rice based on consumer acceptability and preference. The grain quality project plays a key role in the assessment of selections according to standards that are beneficial to the various sectors concerned. In support of the National Cooperative Testing (NCT), the project specifically provides information on grain quality characteristics of rice selections. These characteristics include: 1). Milling potentials (% brown rice, % total milled rice and % head rice); 2) physical attributes (% chalkness, % immature grains, grain length and grain shape); 3) physico-chemical properties (% amylose, gel consistency, gelatinization temperature and % crude protein); 4) cooking parameters (optimum cooking water, % height increase and cooking time), and 5) sensory qualities (% acceptability, preference score, and descriptive characteristics such as aroma, flavor, tenderness, color, gloss, cohesiveness, translucency and brittleness of grains). All rice selection in Phase I of the National Cooperative Testing (NCT) are evaluated for milling potentials, physical attributes and physicochemical properties. Irrigated lowland entries in their 3rd season (2nd year) in Phase I with positive yield advantage over the yield check during the first two seasons are further assessed for cooking parameters and sensory qualities (laboratory panel). Irrigated lowland rice selections in Phase II are assessed for all grain quality parameters twice. Upland, rainfed lowland drought prone and rainfed lowland dry seeded rice selections which have positive yield advantage over the yield check in their first year are likewise evaluated for cooking and sensory qualities on their 2nd and 3rd year in the NCT. Rice entries in other adverse environment such as saline and cool elevated selections as well as traditional varieties for registration to the National Seed Industry Council (NSIC) are assessed for sensory quality when the need arises. Laboratory and consumer panels are employed in the sensory evaluation of rice selections from all the above mentioned environments using samples harvested from the test site. Consumer sensory evaluation is conducted in areas that simulate the agro-ecological environment where the rice entries are grown. UPLB is responsible for the determination of the milling potentials and physical attributes of NCT Phase I irrigated lowland selections. The assessment of the cooking and sensory qualities of entries in NCT Phase II is also undertaken by UPLB. PhilRice on the other hand, conducts the evaluation of the following grain quality parameters: 1) milling potentials and physical attributes of NCT Phase I entries from rainfed lowland (drought prone and dry seeded), upland and other adverse environments as well as of NCT Phase II rice entries; 2) physicochemical properties of all NCT entries and 3) cooking and sensory qualities of promising NCT rice selections and their respective yield checks.

OBJECTIVES

1. To evaluate the milling potentials and physical attributes of all NCT rice entries 2. To analyze the physicochemical properties of all NCT rice entries 3. To establish the optimum cooking water of promising selections in the NCT

Phase land rice entries in the Phase II trials and to measure the cooking parameters of these rice entries

4. To assess the sensory qualities of promising NCT I selections and rice entries in the NCT Phase II

5. To interrelate the various grain quality characteristics 6. To recommend to the breeders the outstanding grain quality characteristics of the

selections for nomination. METHODOLOGY Rice samples for grain quality tests come from the breeders of UPLB and/or PhilRice. Standard yield check varieties for each group and a sensory quality check are grown along with the entries (see Fig.22). UPLB breeders provide the irrigated lowland Phase I entries while PhilRice breeders provide all the other entries in Phase I as well as the rice entries in Phase II. Planting plan is given by the NCT coordinator/ the breeder in-charge to the grain quality group one month after planting. Meanwhile, rice samples for analysis are submitted by the breeder on the second week of June and on the third week of November for dry and wet seasons, respectively. The samples conform with the following:

1. Sample Source. Rice sample for grain quality evaluation come from a composite rough rice of all the replications of the yield trial. Rough rice should be free of rice impurities, straw, leaves, weeds and stones.

2. Moisture Content of Rough Rice. Moisture content of rough rice should be within 12 -14%. It is determined using a standard moisture meter calibrated for rough rice.

3. Amount of Rough Rice Sample:

NCT Phase I Non-promising entries 0.25 kg. Promising selections 3.25 kg. Yield check 3.25 kg. Sensory quality check - non-glutinous 3.25 kg. - glutinous 5.25 kg. Adverse Environments*: Non-promising entries 0.25 kg. Promising selections 4.25 kg. Yield check 4.25 kg. Sensory quality check 6.25 kg./grp.

NCT Phase II Test entries 3.25 kg. Sensory quality check 5.25 kg./grp.

- non-glutinous - glutinous

A. MILLING POTENTIALS Milling yield of rough rice is the estimate of the quantity of total milled rice consisting of head rice and broken grains that can be percentage. To determine the milling yield, 125-g rough sample is passed through a shelling device (SATAKE testing husker) to remove the hulls. The dehulled or brown rice is then polished using miller #2 (McGill or Dayton) for 30 seconds to remove 10% of the bran and the embryos. After the brown rice is polished, head rice is separated from the broken grains. Head rice is described as the whole kernel and those not less than 8/10 in size. The head rice is the separated from the broken grains using a manual sizing device (4.5 grader). The various components as brown rice, total milled rice and head rice are weighed to determine the milling yield and head rice recovery. Using two 125-gram rough rice the various components are calculated as follows:

% Brown Rice = weight of brown rice (g) x 100

125 g

% Total Milled Rice = weight of total milled rice (g) x 100

125 g

% Head Rice = weight of head rice (g) x 100

125 g The percentages obtained are classified based on a scheme developed from research experiences and readings. For each of the parameter, a recommended value/classification is used as reference for varietal recommendation.

Table 6. Classification and recommended value for parameters of milling potentials.

Milling Potentials Classification Recommended Value

% Brown Rice Good (G) 80.0% and above 75.0% and above Fair (F) 75.0 – 79.9% (Fair to Good) Poor (P) below 75.0% % Total Milled Rice Premium (Pr) 70.1% and above 65.1% and above Grade 1 (G1) 65.1% - 70.0% (Grade 1 to premium) Grade 2 (G2) 60.1% - 65.0% Grade 3 (G3) 55.1% - 60.0% % Head Rice Premium (Pr) 57.0 and above 48.0% and above Grade 1 (G1) 48.0% - 56.9% (Grade 1 to premium) Grade 2 (G2) 39.0% - 47.9% Grade 3 (G3) 30.0% - 38.9%

B. PHYSICAL ATTRIBUTES The physical attributes consist of four (4) parameters namely: % chalky grains, % immature grains, grain length and grain shape. Chalky grains are whole or broken grains, one half or more of which is white like the color of a chalk and is brittle. Immature grains are light green and chalky with soft texture. Grain length, on the other hand is the length in millimeters of the rice grain while grain shape is the ratio of the grain’s length and width.

1. Grain length and shape – Grain length and shape are determined by measuring under a photo-enlarger the length and width of ten (10) whole milled grains for each replicate. Based on the average length and length width ratio, they are classified into the following categories.

Grain Length (in mm) Grain Shape (length/width in mm) Extra Long (EL) 7.5 and above Slender (S) more than 3.0 Long (L) 6.6 – 7.4 Intermediate 2.0 – 3.0 Medium (M) 5.5 – 6.5 Bold (B) less than 2.0 Short (S) 5.4 and below

Results of the consumer preference studies for more than 20 years revealed that Filipinos prefer rice grains which are long and slender. Thus, for rice varietal recommendation, grain size of 6.6 mm to 7.4 mm and grain shape of more than 3.0 is used as standard.

2. Chalky and Immature grains. Determination of percent chalky and immature grains is done as follows: weigh two (2) 50 grams sample from the total milled rice. Separate all chalky and immature grains from each replicate and weigh chalky and immature grains separately. Percent chalky and immature grains are calculated as follows:

% Chalky Grains = weight of chalky grain (g) x 100

50 g

% Immature Grains = weight of immature grain (g) x 100

50 g Table 7. Classification and recommended value for % chalky and immature grains in rice.

Classification Recommended Value

% Chalky Grains Premium (Pr) < 2.0% less than 5.0% Grade 1 (G1) 2.0% - 5.0% (Grade 1 to Premium) Grade 2 (G2) 5.1% - 10.0% Grade 3 (G3) 10.1% - 15.0% % Immature Grains Premium (Pr) < 2.0% less than 2.0% Grade 1 (G1) 2.0% - 5.0% (Premium) Grade 2 (G2) 5.1% - 10.0% Grade 3 (G3) 10.1% - 15.0%

3. PHYSICOCHEMICAL CHARACTERISTICS The physico-chemical characteristics of the rice grains are important indicators of

grain quality. These characteristics are referred to as indices of cooking qualities and cooked rice texture. These characteristics are moisture content, gelatinization temperature, gel consistency, amylose content and crude protein.

Amount of working sample is 10 g from the total milled rice 1. Moisture content. Weigh approximately two (2) one gram ground sample and

place in tared aluminum pans (an improvised aluminum foil of 2” x 1” x 0.5” will do). Dry the pan with the sample in an oven (forced draft) at a temperature of 130 ºC for one (1) hour. Cool the dried sample in a desiccator and weigh. Percentage moisture is calculated as:

% Moisture = _____loss in weight (g) ____x 100

Wt of the original sample (g)

2. Alkali Spreading Value. Gelatinization temperature is estimated by the extent of alkali spreading of raw milled rice soaked in 1.70% anhydrous potassium hydroxide for 23 hours at 30ºC or at room temperature. Gelatinization temperature is the range of temperature within which the starch granulates start to swell irreversibly in hot water with accompanied loss of birefringence and crystallinity. Rices with low gelatinization temperature disintegrate completely, whereas rices with high gelatinization temperature remain largely unaffected in the alkali solution. Six (6) whole grains are spaced evenly in a 60 mm x 15 mm transparent plastic culture dish. Make two (2) replication on each rice selections. Ten (10) milliliters of 1.70% potassium hydroxide is added (enough to submerge the grain in solution). The dish is covered and left undisturbed for 23 hours at room temperature visually using a 7-point numerical scale as follows:

Rating Alkali Spreading Value

1 Grain not affected 2 Grain swollen 3 Grain swollen, collar incomplete and narrow 4 Grain swollen, collar incomplete and wide 5 Grain split or segmented collar complete and wide 6 Grain dispersed merging with collar 7 Grain completely dispersed and intermingled

Alkali spreading values corresponds to gelatinization temperature as follows: 1-2, high (74.5ºC - 80º); 3, high-intermediate; 4-5 intermediate (70ºC - 74 ºC); and 6-7 low (<70ºC). Report average alkali spreading value and gelatinization temperature classes in order of decreasing frequency as in the following example:

A sample of 12 grains with rating of: 5 – for 2 grains; for 3 grains; 7 – for 4 grains;

2 – for 3 grains will have an average of 4.42 and the GT classification is L/H/HI/I. this will be reported as 4.42 L/H/HI/I.

3. Crude Protein Determination. This analysis is to be conducted only once for each

selection. Place approximately 100 mg ground sample wrapped in a small piece of filter paper in 100 ml Kjeltec digestion flask. Add a tablet of Kjeltab (3.5 g potassium sulfate and 0.4 g copper sulfate mixture) and 5 ml concentrated sulfuric acid. Place flask in Kjeltec digestion plate inside a fume hood and heat gently, until the solids are dissolved. Continue heating until the solution becomes clear. Cool the flask and add distilled water to dissolve the crystalline mass. Place flask inside Kjeltec autostill for distillation and titration. Add enough sodium hydroxide-sodium thiosulfate solution (40 g NaOH and 5 g Na2S203/100 ml) using boric acid (4%) and alcoholic methyl red indicator as receiving solutions, and 0.1N sulfuric acids as titrant. Note volume of acid used. This is done in duplicate. Run a blank. Compute percent crude protein using the formula.

% Crude protein = _ [ Vol H2SO4 (spl) – Vol H2SO4 (blk) ] x N H2SO4 x 0.014 x 5.95 x 100

Weight of the sample (mg)

Note: Grain and straw may be digested completely in 20 minutes.

3. Amylose Determination 1. Preparation of dispersion of standard checks, samples and unknown.

a. Place in separate 100 ml volumetric flask the exact weight of the following: 100 mg superlose (amylose standard) three (3) 100 mg of IR29 Starch (Amylopectic standard) 100 mg of each defatted (refluxed in 95% ETOH in Goldfish extractor for 2-4 hours) milled rice check. 100 mg of each undeffated milled rice unknown b. Add 1.0 ml 95% ethanol to wet the powder. c. Add 9.0 ml 1N NaOH and swirl very carefully. d. Let stand overnight (18-24 hours). e. Make up to 100 ml with distilled water and mix very well.

2. Preparation of working standards and standards curves. a. Into 100 ml volumetric flask labeled as 0, 10, 20 and 30% amylose, pipet

out the amylose and amylopectin standards according to the following table and make up to 100 ml with 0.09N NaOH.

Working Standards Amylose Amylopectin 0.09N NaOH (% Amylose) (ml) (ml) (ml)

0 0 70 30 10 10 60 30 20 20 50 30 30 30 40 30

Note: To save on standards, everything may be reduced proportionally. For example 50 ml volumetric flasks may be used instead of 100 ml in which case, volumes of amylose and amylopectin indicated in the table may be reduced to half. Standards are run only once for every new set of check and reagents. b. Pipet accurately 5.0 ml from each working standard and transfer to 100

ml volumetric flask. For blank, use 5.0 ml of 0.09 N NaOH. c. Add 1.0 ml 1.0N acetic acid d. Add water to approximately 50 ml and mix e. Add 2.0 ml iodine solution (0.2% iodine in 2% KI) f. Make up to 100 ml distilled water. g. Mix very well and let stand for 15 to 20 minutes h. Read absorbance at 620 nm i. Plot % amylose versus absorbance of 620 nm and determine the

regression equation.

3. Determination of amylose content of check samples. a. Pipet out 5.0 ml of the defatted check sample into 100 ml volumetric flask. b. Do steps c to h as in 4.2 c. Determine % amylose content of the defatted check samples using the

regression equation from the amylose and amylopectin standard curve.

4. Determination of amylose content of undefatted unknown samples. a. Pipet out 5.0 ml of each defatted checks and unknown into 100 ml

volumetric flask. b. Again, d steps c to h as in 4.2 c. Assign the percent amylose values of defatted checks obtained in c to the

corresponding undefatted checks. d. Make a plot of % amylsoe vs absorbance of undefatted checks and

determine the regression equation. e. Use the regression equation to obtain percent amylose of unknown.

Classification of rice according to amylose content is listed below.

WAXY/GLUTINOUS (W) - 0.0% - 2.0% VERY LOW (VL) - 2.1% - 10.0% LOW (L) - 10.1% - 20.0% INTERMEDIATE (I) - 20.1% - 25.0% HIGH (H) - MORE THAN 25.0%

5. Gel Consistency Determination. Gel consistency is a measure of the flow characteristics of milled rice gel. High amylose rices may be differentiated in terms of tenderness of cooked rice by the gel consistency test. Within high amylose group, varieties with soft/medium gel consistency are more tender when cooked than rices with hard gel consistency. Thus, the analysis will be conducted only for entries with high amylose content. The procedure is as follows:

Weigh duplicate 100 ± 1.0 mg of the ground milled rice (100 mesh in 13 x 100-mm culture tubes). Wet sample with 0.2 ml 0.025% thymol blue (25 mg/100 ml ethanol) and mix thoroughly. Pipet 2 ml of 0.2 N KOH into the solution with sufficient mixing (2 to 3 seconds) using a vortex mixer set at speed 6. Cover the tubes with glass marbles. Place each tube at 10 sec. interval into a vigorously boiling water bath for 8 minutes. Make sure that the contents reach two-thirds the height of the tube. Likewise, remove the tubes from the water bath at 10 sec. interval starting with the first tube. Let stand at room temperature for 5 min. and then into an ice water bath for 20 min. Lay the tubes horizontally over ruled paper graduated in milliliters and leave undisturbed for 1 hour. Measure the length of the gel from the bottom of the tube to the gel front. The test separates rice into the following classification: Rating Length in mm Hard 25-40 Medium 41-60 Soft 61-100

D. COOKING PARAMETERS AND SENSORY EVALUATION OF MILLED RICE The milling and cooking procedures affect the quality of the milled raw and cooked rice grains. Using a standardized method to evaluate the cooking parameters and sensory attributes is therefore necessary. Working samples for cooking and sensory assessment are milled three (3) moths after harvest. This aspect of the evaluation ideally starts on the 1st week of September for dry season entries and on 2nd week of February for wet season samples. Cooking and sensory assessment are done at UPLB and PhilRice. All samples for evaluation using a laboratory panel are sent to PhilRice. These are the samples in NCT Phase I glutinous and non-glutinous irrigated lowland rice entries planted, harvested and evaluated for milling potentials and physical attributes at UPLB as well as other NCT Phase I entries that are planted in PhilRice. Meanwhile, samples for consumer testing are assessed at UPLB which includes NCT Phase II rice entries grown in Maligaya. 1. Preparation of Samples for Cooking and Sensory Analysis. The samples (3 kg for promising/yield checks and 5 kg for the quality check) are divided into one (1) kg portions. Each is dehulled in the SATAKE rice defuller and milled in the McGill Miller #3. Milled samples from each 1 kg portion are combined. Broken grains are removed using a sizing device (SATAKE ricegrader). Other foreign matters such as chaff, stones, paddy and seeds not completely removed during the previous steps are picked up by hand. The head rice recovered and cleaned is placed in glass jars labeled with assigned three digit code number on top of the selection name. 2. Cooking Quality Test. Cooking quality evaluation starts with the determination of the optimum cooking water followed by the measurement of height increase and cooking time. The optimum amount of water for cooking different rices to similar doneness (neither too dry nor too soft) is determined after preliminary cooking trials.

a. Determination of Optimum Cooking Water for Non-glutinous Rices. The cooking vessel is an electric rice cooker (National SR-3F) with a capacity of two (2) cups. Measure 80 grams head rice into the inner pan; add 120 ml tap water. Swirl the pan three (3) times to wash the rice. Decant and measure the wash water. Replace the wash water with the same amount of tap water. Fit the inner pan to the cooker and cover. Plug the rice cooker to an outlet connected to a variable transformer which can be adjusted to maintain a uniform flow of current (220 V). Switch on the rice cookers undisturbed for 15 minutes. Mix the cooked rice and get representative sample for evaluation by laboratory staff who are trained to determine doneness of cooked rice. Atleast three (3) evaluators are required. The laboratory evaluators taste and press a few cooked grains between the forefinger and thumb and doneness. Based on the evaluation, the water is reduced or increased until the optimum amount of water is achieved for each rice selection.

b. Determination of Height Increase and Cooking Time. Follow the procedures above using the optimum amount of cooking water for each selections. Using a sliding steel tape calibrated in millimeters, measure the height or depth of the uncooked and cooked rice in the inner pan at

three points (i.e. middle, right middle, and left middle sides). Record the exact cooking time in minutes and in seconds using a stopwatch (switch on and of simultaneously rice cooker and stopwatch). Convert time into minutes. Percent height increase in calculated as follows:

% Height Increase = _____ht. of cooked rice – ht. of uncooked rice ____x 100

ht. of uncooked rice

c. Cooking of Glutinous Rices. Glutinous of waxy rice selections are cooked as “suman inantala”. The preparation is selected for two (2) reasons. First, the ingredients are evenly absorbed during cooking. In addition, “suman inantala” is customarily eaten as is. The problem of controlling the amount of other ingredients like sugar and grated coconut which are served together with other “suman” preparations is dealt with. Second, is for a built-in evaluation of tenderness and cohesiveness. “Suman inantala is eaten after standing overnight at room temperature which permits evaluation of tenderness and cohesiveness after cooling. Preparation of the “suman inantala” are as follows:

1. Preparation of banana leaves for wrapping. Separate banana leaves from

the leaf stalk. Roll and dip in boiling water. Unroll and dry with a dish cloth. Cut into 8-inch wide pieces and set aside.

2. Preparation of coconut milk. Add one (1) cup warm water into 3 ½ cups mature grated coconut. Squeeze. Repeat extraction adding ½ cup water. Mix both extracts and set aside.

3. Pre-cooking the glutinous selections. Place 200g glutinous rice into the inner pan of a rice cooker (110V). Add 300 ml tap water. Wash once by swirling gently for five (5) times. Decant wash water immediately to prevent soaking and drain the rice for 10 minutes. Place the drained rice into the inner pan. Add 1 1/3 cups coconut milk and one teaspoon (3 grams) salt. Mix well with a wooden spoon. Pour 40 ml distilled water into the outer pot of the rice cooker. Put the inner pan with the sample into the outer pot and cover the cooker. Plug the rice cooker to an outlet connected to a variable transformer to maintain uniform flow of current (110V). Switch on the rice cooker and switch off after 15 minutes. Uncover cooker and stir mixture. Return cover and leave undisturbed for 10 minutes.

4. Steaming the “suman”. Spread evenly three (3) tablespoon of the precooked glutinous rice-coconut milk mixture and wrap on the non-glossy side of the wilted banana leaf. Wrap evenly to ensure even thickness through a 4 inch length. With the end folds facing each other, tie the pieces in pairs. Arrange in a single layer inside a steamer and steam for 30 minutes. Let stand overnight r 10-12 hours prior to serving for sensory evaluation.

3. Sensory Evaluation Sensory evaluation is used to interpret sensations perceived by the human senses of sight, smell, taste, touch and hearing. The complex sensation that results from the interaction of senses is used to measure food quality in works dealing with quality control and product development. In as much as sensory tests are valuable in predicting consumer reactions it is one of the tool used in the National Cooperative Testing to screen quality. Sensory assessment is conducted for promising Phase I and Phase II rice selections as well as traditional rice varieties for registration s NSIC varieties. Sensory evaluation of NCT Phase I entries is conducted using a trained laboratory panel while NCT Phase II entries are assessed using both laboratory and consumer panels. Moreover, consumer panel evaluation for promising entries grown in adverse environment will be conducted in areas where they are grown prior to varietal nomination. 1. Experimental Design. The use of a consumer panel requires an experimental

design to establish the required number of sensory participants and the sample placement or each judge. The number of rice samples per maturity group varies hence an experimental design is necessary to ensure that each entry is evaluated no less than 30 times and has interacted at least 10 times with each other.

Based on the appropriate experimental design (Cochran and Cox 1975), each judge is asked to evaluate a maximum of four (4) non-glutinous samples and three (3) glutinous samples, including the sensory quality check, at any one time for preference and acceptability. In using the laboratory panel, randomization of the samples for presentation is applied. A minimum of two (2) and maximum of four (4) entries are evaluated at any one time. The laboratory panel describes the characteristics of each test entry rather than compare samples. Quality check is always evaluated with the test entries.

2. The Test Subjects: Panel of Judges. Sensory assessment is based on a person’s perceived judgment through the use of the senses. Therefore, it is not suitable to depend on few untrained person’s judgment. Instead, testing should be conducted employing a group of persons who are known to be consumers of the food being evaluated.

Two (2) types of panel namely; laboratory and consumer panels are employed in rice sensory tests. The difference between the two lies in what is measured, the level of skill required to make the measurement, and the composition of the judges.

Laboratory Panel Consumer Panel

1. Measures sensory differences. Describes or characterizes a food product in terms of cooked rice attributes as aroma, color, flavor, tenderness, gloss, cohesiveness and texture as well as raw rice attributes like aroma, color, gloss, translucency of grains, wholeness of grains and brittleness of grains.

1. Measures preferences and acceptability. Determines acceptability (likes or dislikes) preference where choice is involved. General characteristics are considered.

2. The number of panel members is small. Consist of five (5) to ten (10) panelists.

2. The number of panel members is large. Usually 30 to several hundred of persons as the case warrants.

3. Trained. The members are selected from a large group for their acuity and consistency in recognizing differences.

3. Untrained. The ability of its members to discriminate according to degree for specific attributes is not considered as long as they are representative of the consuming public and are willing to participate.

Absence of colds or other diseases that reduces sensitivity of the sense is also considered a criterion in choosing participants for sensory evaluation. Similarly, eating and smoking time is also considered. There should be at least one (1) hour interval between eating and /or smoking and time of evaluation particularly for cooked milled rice. Drinking liquor before sensory evaluation is strictly prohibited.

3. Sensory Room and Sample Preparations. The test area should be comfortable, spacious, well ventilated, lighted, free from distractions and is accessible. Such atmosphere of comfort and relaxation is a must to encourage panel members to concentrate on evaluation tasks. Samples for sensory testing should be prepared in such a way that no foreign taste or odor is imparted. Sample size container and temperature must be similar for all. Coded samples are to be served at random to avoid time of position error.

4. Coding the Rice Samples. Three digits are assigned as code number for each

of the entries. To code each rice entry for sensory evaluation, a table of random numbers from any statistics book is used.

5. Sample Presentation for Sensory Evaluation. Prior to the distribution of

samples for sensory evaluation, background information sheet is distributed and accomplished by each participant. Score cards are fully explained to the participants to minimize error in answering the said forms during the evaluation.

Cooked Non-glutinous Samples. Warm cooked rice samples are placed in wine glasses covered with aluminum dish. The code for each sample is placed at the bottom of the wine glasses and on the dish. The sample containers are arranged on trays according to the experimental design (consumer panel) or randomized plan (laboratory panel). A glass of water and a teaspoon are provided. Cooked Glutinous Samples or “Suman”. Following the order of the experimental design, uniform slices of “suman” samples (4x3x1 cm) are arranged in oval tray

labeled with the respective code number for each sample. A fork and glass of tap water are provided. Milled Raw Samples. Head rice is specifically used in their sensory assessment of raw rice. This is to promote uniformity of the samples presented to each panelist. One (1) spoon (5-7g) of head rice sample is placed inside the compartment of the miniature rice bin which has been labeled with code numbers arranged according to the experimental design. Milled raw rice samples are presented to the sensory panelist after the cooked samples have been evaluated.

6. The Score Cards and Background Information Sheets. Sets of score cards were developed specifically for the National Cooperative Testing. These include the score cards for both the laboratory and consumer panels (Appendix 14-20)

The score cards for laboratory panel consist of score sheets for cooked and raw milled rice. The entries are described/characterized. Four (4) score cards are used for the consumer panel. These are: 1) the scorecards for cooked milled non-glutinous 2) the score cards are used for raw milled non-glutinous rice; 3) score cards for “suman” or cooked glutinous rice and 4) scorecards or “malagkit” or raw glutinous rice. Acceptability and preference scores for the selections are highlighted. Score cards for consumer panel are available in two (2) versions namely, Filipino and English. Background information sheet are likewise developed for consumer sensory evaluation. These questionnaire and score cards (laboratory and consumer) were based on del Mundo A.M. (1991).

7. Determination of Preference Score and Percent (5) Acceptability. NCT Phase II rice entries are evaluated by a laboratory and consumer panel for descriptive characteristics as well as preference and acceptability. Preference is determined by ranking and is expressed in scores of ranked data following the procedure of Larmond (1985). Acceptability is indicated by a “yes” or a “no” response.

Preference Score. The ranks of the four (4) non-glutinous rices are converted to scores. The equivalent scores for the first, second, third and fourth ranks are +1.03, +0.30, -0.30 and -1.03, respectively. Since each sample is judged 30 times, the highest possible preference score is 30.9 (i.e. 1.03 x 30).. This is applied for the ranks of both cooked and raw samples. In cases wherein a maximum of three (3) samples are presented, as in glutinous selections, the ranks are transformed into the following scores using +0.85, 0 and -0.85 for the first, second and third in that order. Having 30 judges, the highest possible score 25.5 (i.e. 0.85 x 30). The scores are then compared with the scores obtained for the quality check variety using Duncan’s Multiple Range Test. Rice entries with positive preference scores which are comparable or better than the sensory quality check are considered for varietal recommendation. Percent Acceptability. Acceptability is expressed in percent of the “yes” responses. If among the 30 judges, 29 responded “yes” then the rice sample is

96.67% acceptable (i.e. 29/30 x 100). A score of 75% and above is considered acceptable.

Procedure for Location Specific Recommendation BACKGROUND Varietal release procedures are similar among countries. They are based primarily on proof of superiority and the availability of mechanisms to produce and distribute quality seeds. Procedures are often designed to cater to very large areas. As a result, release of varieties for location specific problems and small or scattered areas is hampered. In the Philippines, there are several adverse rice growing environments. They are: drought-prone uplands and lowlands, acid upland lowlands, coastal saline lowlands (irrigated and rainfed) and lowland temperature affected areas of the mountain provinces. Of these, the extents are large (>100, 000 ha) for the acid uplands and drought prone uplands and lowlands. The others are similar areas and widely scattered. Acid lowlands are in Cagayan Valley, Bicol, Region, Visayas and Mindanao. They are confined to coastal areas and the extent is less than 10, 000 ha. Salt affected rainfed lowland are also in coastal areas but distributed throughout the country. The extent is estimated 20-30,000 ha but in any one area the maximum may be less than 500 ha. Irrigated lowlands with salinity problem are in the Bicol region. Affected extent varies depending on irrigation and the maximum is about 10, 000 ha. About 30,000 ha of lowland rice in the mountain provinces (Ifugao, Benguet, Mt. Province, and Kalinga Apayao) are affected by low temperature. Farm size is another important factor in these environments. In the Mountain Provinces, for example holding size of few hundred square meters is very common. As a consequence, seed needs of a farmer are also very small. They usually produce their own seed. Exchange of seed or seedlings or rough rice is common and seed purchase is extremely rare. Severity of a stress can vary even within a short distance. Sometimes cultural practices differ within an environment with similar stress. As a result, varieties grown within an environment can be large. Therefore, unlike in favorable environments, many different varieties are grown even within a small area. The spread of a new variety depends on the availability of seeds. Production and distribution of quality seeds involve time consuming, laborious, and expensive processes of maintenance and production of breeder, foundation, registered and certified seeds. It is virtually impossible and on the other hand, unjustifiable to produce such expensive seeds for farmers whose holding size is small and yield is low. Moreover, because of wide scattering of these lands, costs involved in making seeds available to farmers will be very high and their recovery will be doubtful.

PROCEDURES

1. Test new line varieties in NCT for two seasons.

There may be environments where a standard check cannot be found. For example, there are about 100 different local varieties grown in Banaue, and is difficult to find a commonly grown variety. In such cases, any one variety may be used as the check.

In problem soil areas, the stress vary from year to year and also from place to place. Monitoring soil stresses is laborious and expensive. It is convenient to use a sensitive variety also as a check to determine whether the stress has occurred or not.

2. Identify promising line/s.

Stability over time and space that reflects stress tolerance should be the main criterion used in selecting promising lines.

Very stress tolerance by controlled experiments.

3. Investigate other important agronomic and acceptability traits.

Because of low productivity, pests are not very common in adverse environments. For cold temperature affected areas, resistance to blast disease is essential.

Grain quality-traits should not be judged by national standards.

4. Seed increase promising lines.

Use stress-free areas or lands.

Initial production of about 50 kg. is considered adequate.

Production of good seeds for saline/cool elevated areas.

5. Maintain purity

Maintain varietal purity by producing about 10 kg certified seed, every year, until the variety is replaced.

6. Release new varieties more often.

Any new variety may not find adaptable to all lands of the specified area/location. Because, the number of NCT sites is limiting and moreover stresses vary within an environment. Frequent releases allow varieties to find their own niche.

Policies and Guidelines for Hybrid Rice Testing, Release, Seed Production and Utilization BACKGROUND

With our fast growing population growth, exarcebated by decreasing area of prime rice lands, there is an imperative need for Fililpino rice farmers to dramatically increase production to meet the demands beyond the year 2000. Yields of modern inbred lines have been claimed to have reached a plateau. New technologies therefore have to be tried to overcome this phenomenon and the most promising tool is hybrid rice. Dramatic increases in rice production have been observed in China where hybrid rice is successfully grown. In the Philippines, the heterotic effects of hybrid rice based on experimental and on-farm trials showed an increase of 15-30% over the best inbred line in some favorable test sites. Higher yield of hybrid rice was due to increase in total biomass, spikelet number and 1000 grain weight. In the present testing scheme the same cultural management practices have been used both on the inbred and hybrid rices. Modifications, therefore, on the management practices especially on fertilizer requirement will probably further maximize yield of hybrid rice under Philippine condition.

1. Identification of the Potential Hybrid a. The potential hybrid will be identified on the basis of performance at test

locations over seasons and years in the NCT. b. The yield advantage of 0.75 t/ha over the check variety and the best pureline

entry for a particular location-season-year combination will be considered. The 0.75 t/ha yield advantage is equivalent to 15% of 5 t/ha.

2. Target environment a. The sites that consistently show the superiority of the hybrid over the pureline

check shall be identified. Hence, only the favorable environments shall be considered for full expression of potential yield.

b. The potential sites will be identified on the basis of yield performance in a particular location over time and the presence of abiotic and biotic stresses.

c. Consideration of location/season performance will be determined to find out if hybrid rice will be planted during the favorable season only or only in particular regions.

d. The response of the farmers to adopt the new technology will also be determined in the process, especially during the pilot stage.

3. Test Areas (Table 2) 4. Agencies/ Institutions Involvement

The responsibilities of each agency/institution are as follows: PhilRice Breeding, Breeder (Parents A, B, R) and hybrid

seed production, (A X B & R) demo farm establishment or piloting, training and provide foundation seeds of parental lines to bonafide or accredited private or public seed growers.

IRRI Breeding, Production of nucleus and breeder seeds of parental lines of released hybrids for sharing with public and private seed growers; training

BPI Coordination/Regulatory and accreditation of seed

growers. DA (BIARC, Production of hybrid seeds (A x B & R) WESVIARC, other DA-ROS) ACU’s (UPLB, USM, CMU, Production of hybrid seeds (A x B & R)

CPU)

ATI Training Private companies Production of hybrid seeds

5. Timetable (At least 2WS/2DS)

DS Yield Trial

WS Yield Trial

DS Yield Trial + seed production of most promising hybrid by prospective seed grower

WS Yield Trial + evaluation of seed grower’s produce (grow-out or seed quality tests)

The parents of the hybrid entries should also be planted alongside the experiment to record their flowering dates and other agronomic characteristics that are essential in F1 seed production.

6. Seed Certification Standard The seed certification standards will be based on the same guidelines for hybrid corn. Documentation will be required especially on the technical processes involved during the seed production per se. However, the RVIG will further draft the specific standards to comply with the Seed Certifying Agency. Distinctness, Uniformity and Stability Trial (DUST) BASELINE INFORMATION NEEDED

Characterization and evaluation of all PSB-released varieties. Information gathered for each will serve as the reference to determine distinctness of new varietal releases. Proposed Guidelines

1. The Distinctness Uniformity and Stability Trial (DUST) will be conducted in close supervision of the breeders.

2. All entries in the NCT I should be characterized and evaluated to determine the possible reference variety for comparison in the DUS trial.

3. All lines in the NCT II trial should compose the DUS trial. 4. The DUS trial should be conducted in the ecosystem where the entries are

intended to be grown. 5. Each entry in the DUS should be planted along with the reference (standard,

PSB-released).

6. The DUS trial should be conducted for at least 4 seasons (2 dry and 2 wet seasons).

Guidelines for Monitoring trips The monitoring groups shall be composed of at least two members. All selected members of the RTWG will lead in the monitoring. The monitoring team should be composed on an agronomist/plant breeder and a crop protection specialist. The team should have an entry and exit briefing. Monitoring trip report should be prepared using appropriate evaluation sheets (Appendix 21-23) by the group before leaving the station visited. The team should also discuss with the study leader of the NCT site their comments and recommendations. The group leader is required to submit a final report to the chairman and NCT coordinator of the RTWG immediately after the trip. Monitoring results will be incorporated in the incoming RTWG regular meeting. The group shall evaluate field performance tests Phase I and II, disease and insect screening trials. It should assess the general management of experiments and varietal differences. Information asked for in the information sheets should be answered. Evaluation of entries/varieties should follow the guidelines contained in this manual. Selections identified for further testing and seed increase in the preceding RTWG meeting should be carefully scrutinized.

Documents

National Cooperative Testing · The National Cooperative Testing Project for rice (NCT) was started in 1954 by the Bureau of Plant Industry (BPI), University of the Philippines College