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Volume 8 Issue 2
May 1, 2011
Late-Season Weed Control 1
Differences in Pure line & Hybrid Seed Production 2
Why is Timing so Critical in Rice Fungicide Application? 3
Dr. H. Rouse Caffey Honored 3
Pest of the Quarter Bacterial Panicle Blight 4
Update on Marker - Assisted Selection 5
Area Field Days 5
Focus 6
Special Dates of Interest:
Rice Research Station Field Day, Crowley, LA, June 30, 2011
INSIDE THIS ISSUE:
A common question each year is: “What herbicides can I use on late emerging weeds or weeds that were not controlled in earlier applications?” This can often be difficult to answer because of the limited number of products available for use in the late growing season.
I rarely recommend growers use a reduced-rate herbicide program or increase a herbicide rate to the higher end of the labeled rate. Reduced-rate programs are useful but oftentimes cost more money because more applications are needed over a growing season. Reduced-rate programs often have late-season weed problems that cost more to control. The new herbicides labeled in the past five to 10 years are not as rate reactive as older herbicides; therefore, increasing the rate may not increase weed control, but it will increase the costs.
Making the right decision requires knowing the field’s history. Weed spectrums in a given field normally do not drastically change from one year to the next. It is a good idea to keep records of weeds in a field from year to year. If a problem occurred in a field one year, the following year a herbi-cide program can be selected to manage that problem early and not let it develop into a major problem. The best late-season weed control is a preventative early-season herbicide program.
All herbicides should be applied early in the growing season at the correct application timing and at the correct application rate. In these economically strapped times, it is tempting to wait to apply 2,4-D for the cost effectiveness of this herbicide. This is a viable option and one I often recommend; however, if adverse weather conditions occur, as was the case in 2004, the short 2,4-D application window may be missed. If this occurs, there are few options to the producer, and the cost of the products increases substantially. Most herbicides have a window of application from emergence to late-tillering or panicle initia-tion.
Permit is a herbicide that can be applied up to 48 days prior to har-vest; however, Permit is not as effective on large broadleaf weeds compared with an early-season application, but it can be used to sup-press seedpod production of hemp sesbania and Indian jointvetch. Storm and Ultra Blazer are labeled up to the early boot stage of rice, but weed size is important when applying these herbicides late-season.
The grass herbicides are labeled up to late-tillering for Ricestar HT and 60 days prior to harvest for Clincher. Clincher has been successful at controlling grass weeds late sea-son; however, it can be inconsistent if it is relied on to control large grasses. Do not apply Clincher or Ricestar HT late-season if the weeds are under drought stress. I recommend a shallow flood at the time of application to obtain adequate control.
Production practices can also help in controlling weeds before they become a problem and, in many cases, may be more economical. Start the season with a clean, well-prepared seedbed. This can be accomplished by tillage or by an effective stale seedbed burndown program. If planting stale seedbed, the first application of a burndown herbi-cide should be four to six weeks prior to planting and may require a second application near planting. Plant the correct amount of seed as recommended by the LSU AgCenter to establish a uniform rice stand to outcompete the weeds for water, nutrients and sun-light. A uniform stand can be effective in controlling weeds such as ducksalad and the perennial grasses. Surface-irrigate the field as needed to prevent drought stress and establish the permanent flood as soon as the rice is large enough to survive in the water.
Late-season weed control can be achieved, but it is oftentimes expensive and incon-sistent. Research at the LSU AgCenter’s Rice Research Station has shown that weed control in the first three to four weeks after emergence is the most important time to achieve increased yields and prevent late-season weed problems.
BARNYARD
GRASS
Dr. Eric Webster [email protected]
Page 2 Volume 8 Issue 2
Seed production of pure-line rice is relatively easy because rice is a self-pollinated small grain. However, seed production from hybrid rice has to rely on male sterility so it is a very complicated process and technologically de-manding. Because the success of a potential hybrid rice variety primarily depends on whether or not its seed can be economically produced and with the acceptable quality, seed productivity is always an important breeding goal and will be evaluated through-out the entire breeding process.
Currently, both cytoplasmic male sterility (CMS) and environmentally (photoperiod and temperature) sensitive genic male sterility (P/TGMS) systems have been employed in the commercial production of hybrid rice seeds. The former consists of three lines that include A (male sterile seed parent), B (maintainer), and R (restorer), while the latter only includes S (male sterile seed parent) and pollinator (male) lines. The S line can be multiplied by selfing when planted in a fertility-inducing environment (short daylength and low temper-ature), while in a sterility-inducing environ-ment (long daylength and high temperature), it becomes male sterile and may serve as a seed parent in producing F1 hybrid seed. Hy-brid seed production involves multiplication of pollen parents (B, R and pollinator), which is similar to seed production of pure-line varie-ties, multiplication of male sterile (A/S) line
and production of hybrid seed. The multiplica-tion of the A/S line (female parent) must be carried out before the production of hybrid seed.
Seed yield potential is determined mainly by both the yielding ability and outcrossing rate of the male sterile line used in hybrid rice seed production. In the development of adapted male sterile lines, a number of outcrossing characteristics have to be selected, which include small and horizontal flag leaves, full panicle exsertion, synchronized flowering of seed and pollen parents, large stigma size, long style, good stigma exsertion, right time of blooming, long duration of floret opening, and wide angle of floret opening.
Besides pure parental lines, a number of cultural practices have to be considered to achieve maximum seed yield and excellent quality. These include land selection and isola-tion, determination of planting dates for both parental lines to achieve synchronization of flowering at the optimum time, adjustment of flowering, application of gibberellic acid (GA3), supplemental pollination, and elimination of off-types by rigorous roguing. Since rice pollen can travel long distances through the wind, strict space isolation of 300 and 600 feet from other rice varieties for seed production and A line multiplication, respectively, should be maintained.
Because hybrid seed set on the female (A or S) line primarily depends on its flowering syn-chronization with the pollinator or restorer (R) line, male and female parental lines must be planted accordingly to achieve such a goal. Nonetheless, such well-planned planting sometimes still cannot guarantee the perfectly synchronized flowering of both male and fe-male parents because of their differential reactions to changing environmental condi-tions. In such cases, fine-adjustment of flower-ing date of either parent will be carried out by different nutrient and/or water management practices. Based on Chinese experience, a female:male area ratio of 3-3.5:1 is essential to achieve good seed yield by balancing be-tween the maximum number of female florets and enough male pollen grains to fertilize and produce hybrid seed.
Application of GA3 is probably the most important cultural practice for hybrid rice seed production. Spraying GA3 not only improves the panicle exsertion of the male sterile seed parent but also increases the duration of the floret opening, improves stigma exsertion and stigma receptivity, and widens the flag leaf angle. Supplementary pollination can greatly enhance the outcrossing rate, therefore, in-creasing the seed yield. By choosing the ideal parental lines and applying the best cultural practices, a seed yield of 6,600 lb/A has been reported in China.
Multiplication of the cytoplasmic male sterile line 08A in Crowley, LA, 2010. Two male (08B) rows were alternated with six female (08A) rows. A space isolation of 300 ft from other rice varieties was applied.
Production of the potential medium-grain hybrid LAH10 in Crowley, LA, 2010. Two male (R609) rows were alternated with 12 female (08A) rows. A space isolation of 170 ft from other rice varieties was applied.
Dr. Xueyan Sha
Page 3 Volume 8 Issue 2
Dr. Don Groth [email protected]
Fungicide timing must be based on the most damaging disease present in a field. This is deter-mined by knowing the varietal susceptibility, field disease history, what is occurring in your area and, most importantly, by scouting for disease in the field multiple times during the growing season. If sheath blight or grain smuts are significant in a field, a boot application is normally best. If blast is present, a heading application of a fungicide would be best, even if other diseases are present. A boot application has little, if any, effect on blast development. If Cercospora is present, any time between boot and heading would be effective. Other reasons fungicide application timing is criti-cal include the following:
♦ Early applications are effective for a time but often wear off before plant maturity, usually requiring higher rates or more than one appli-cation.
♦ Fungicides are not curative. Any tissues infected by the fungus are dead and lost. Fungicides are protective and must be ap-plied before damage occurs.
♦ Post-heading applications are not effective for any disease.
♦ If an epidemic is developing rapidly or environmental conditions are favorable, it can take more time to stop disease development. Occasionally, the fungicide cannot stop this development.
Why is Timing so Critical in Rice Fungicide Application?
On February 10, 2011, the Rice Research Station hosted a reception to recognize Dr. H. Rouse Caffey and to pay tribute to the recent naming of the Rice Station developed rice variety in his honor. The reception was at-tended by over 70 individuals. Dr. Caffey was the Director of the Rice Station from 1962-70 and later be-came Chancellor of the LSU AgCenter. Throughout his career and even today, Dr. Caffey is a strong supporter of the rice industry in gen-eral and AgCenter research and ex-tension efforts, specifically. The new variety “Caffey” is a very high yielding, high quality medium grain that is being grown on over 500 acres of registered seed production in 2011. Dr. Caffey and Dr. Linscombe
Dr. Caffey with children Rex and Belle
Page 4 Volume 8 Issue 2
Bacterial panicle blight, caused by the bacteria Burkholderia glumae and gladioli, reared its head again last summer as one of the most important rice diseases in the South. The disease is favored by hot (above 95 degrees F during the day and 80 de-grees F at night) and dry weather. The disease causes reduced yields and poor milling with loss estimates ranging from a trace to 70 percent. The bacteria are seed-borne and soil-borne and have caused seedling blights in other countries. The bacteria appear to survive on the plant as an epiphytic population on the leaf and leaf sheath and follow the canopy up. This population infects the grain at flowering and causes grain abortion and rotting during grain filling. The disease is first detected as a light to medium brown discoloration of the lower third to half of hulls shortly after pollination (Figure 1). The stem below the infected grain remains green. Fertilization occurs, but the grain aborts sometime after grain filling begins. Over time, diseased grains become gray to black or pink because of growth of secondary fungi. The disease tends to develop in circular patterns with the most severely affect-ed panicles in the center remaining upright because of the grain not filling (Figure 2). The pathogen also sometimes forms a linear lesion on the flag leaf sheath extending down from the leaf-blade collar. The lesion is distinct and has a reddish brown border with the lesion center becoming necrotic and gray. The lesion may reach several inches in length. Currently, no chemical control measures are recommended. Some varieties have more re-sistance than others. Rice planted later in the season and ferti-lized with high nitrogen rates tends to have more disease.
Pest of the Quarter Bacterial Panicle Blight
Dr. Don Groth [email protected]
Fig. 2
Fig. 1
The LSU AgCenter Rice Research Station is now on Facebook. The page will pro-vide timely updates on research conduct-ed at the station as well as other useful information. The page can be accessed at the link below. Simply go to the page and click on LIKE. Updates will then be posted to your Facebook homepage. If you are not currently a user of Facebook, signing up is easy and free. http://www.facebook.com/#!/pages/LSU-AgCenter-Rice-Research-Station/212812622077680
The 2011 LSU AgCenter Rice Research Station's Rice Cam field was planted on Tuesday, April 12. The field has founda-tion seed production of three Clearfield varieties. Each variety was planted on approximately four acres. The three varieties are (left to right) CL151, CL131, and CL161. Each variety was seeded at approximately 45 lb per acre. The Rice Cam can be accessed at http://www2.lsuagcenter.com/ricecam
Greetings from Louisiana rice country! This year, the blog will concentrate on research conducted at the LSU AgCenter Rice Research Station, in addition to showing the progress of a 12-acre field of rice planted to produce foundation seed. We encour-age your comments and thoughts to help improve this online tool. If you would like a photograph of a particular piece of equipment or a better explanation of a process, let us know. The blog can be accessed at http://lsuagcenterrice.blogspot.com/
Page 5 Volume 8 Issue 2
Recent development of high throughput marker assays – single nucleotide polymorphisms (SNPs) chip (the 44K chip for genotyping), 1536-SNP assay, and 384-SNP assays (Breeder’s chip) – will provide additional tools to streamline the development of new markers for various traits and pro-vide direct support to breeding and cultivar development. These new tools will not only facilitate genetic studies and breeding applications but also foster collaborations among diverse rice research groups throughout the world. The marker-assisted selection program at the Rice Research Station will incorporate any available and affordable new tools to help reach its target goals. The new tools and genomic advancement can provide an ac-cess to a global source for novel traits and allow direct integration to the breeding lines to re-purpose them locally and strengthen Louisiana rice quality and production. The marker-assisted breeding project has evaluated several thousand advanced lines carrying multiple blast-resistant alleles (verified using DNA markers), rows of F2 and F3 lines containing multiple allele combinations of two to three quality traits (cold and salt tolerance; cold and drought toler-ance; and cold, drought, and salt tolerance) from two- to four-way crosses, and 1,000 progeny rows for accumulation target traits from multi donor lines through specific multiple backcross schemes. In all cases, marker screening was imposed in the early generations to obtain its efficiency in cost and labor involved. For single gene target, fixed target alleles can usually be obtained from the screening of the F2 or F3 progeny lines. For a multiple gene target, more elaborate crossing schemes were used so that the volume of marker screening can be kept at its lowest level. Once the target genes have been fixed, the progeny lines were advanced and subjected to regular breeding selections in order to identify the most viable breeding lines that can potentially be released. From 1,000 progeny rows developed through backcross to incorporate traits from multi donors, 400 lines were selected and will subsequently be advanced. Some select advanced lines are currently being tested in the preliminary yield (PY) trials to determine their potential yields, as well as other important quality traits. Efforts are also being focused on direct mapping utilizing a subset of closely related sister lines found within a high protein population. This subset of sister lines uniquely shares a great deal of similarity in various agronomic characteristics but exhibit discretely different total grain protein contents. These lines provide a rare opportunity to allow for tagging genes through direct fine mapping to determine genomic association with high protein content in the grain. Both well-established rice markers (i.e. microsatellite markers of known positions; 240 markers) and a robust molecular marker system (AFLP; 1,078 markers) were screened for their potential applications to saturate genomic regions associated with high protein content using bulked segregant analyses of two pooled genotypes (i.e. control/reference checks and high protein group). This screening yielded 10 highly informa-tive AFLP polymorphic markers and two SSR markers that are associated with genetic differences between the two pooled genotypes. Marker profil-ing analyses identified potential genomic regions corresponding to 49% of the total percentage of protein content increase in the grain. The tagged region was further fine mapped by populating the region with more markers through directed introgression to break up the genomic segment around the identified marker using a genomic donor from an indica cultivar. Individual unique introgressed lines carrying specific disrupted fragments have helped fine map the target genomic region and provided quantification of the relative importance of the disrupted portion of the region associated with grain protein increase. This finding is being verified in this growing season.
UPDATE ON MARKER-ASSISTED SELECTION
Example of gene chip
A single-nucleotide polymor-phism (SNP, pronounced snip) is a single nucleotide variation in DNA sequence, i.e. when a single nucleotide — A, T, C, or G — in the genome (or other shared sequence) differs be-tween members of a species or paired chromosomes in an indi-vidual; Picture from http://en.wikipedia.org/wiki/File:Dna-SNP.svg. A SNP genotyping equip-
ment/mass spectrometer
Dr. Herry Utomo
Rice Research Station Field Day, Crowley: Thursday, June 30, 2011 Evangeline Parish Rice Field Day, Mamou area: Tuesday, May 24, 2011 Southwest LA Rice Field Day, Fenton/Welsh area: Wednesday, June 1, 2011 Acadia Rice and Soybean Field Tour, Crowley: Wednesday, June 15, 2011 North LA Crops Field Day, Rayville: Wednesday, July 13, 2011 Vermilion Parish Rice Field Day, Gueydan area: July 5, 2011
Page 6 Volume 8 Issue 2
www.lsuagcenter.com/en/our_offices/
research_stations/Rice/
Rice Research Station 1373 Caffey Road Rayne, LA 70578
Phone: 337-788-7531 Fax: 337-788-7553 E-mail: [email protected]
Research partially funded by the Louisiana Rice Research Board The LSU Agricultural Center is a statewide campus of the LSU System and provides equal opportunities in programs and employment.
This newsletter is
produced by:
Karen Bearb
Bruce Schultz
Don Groth
Darlene Regan
Steve Linscombe
Linda Benedict
John Sonnier started working at the Rice Research Station in June 1991, almost 20 years ago. “I was straight out of high school,” he said.
He worked at the station part-time and during summers while attending Crowley High School, and in his senior year he worked with Dr. Ray McClain, LSU AgCenter crawfish researcher.
Sonnier’s father, Oday Sonnier, worked at the station, and he has since retired.
Sonnier now works on anything related to crawfish, from catching them to producing them, and he carries out the field work for McClain’s research.
In 2006, Sonnier won the Award of Excellence from the Chi Epsilon Sigma for his work. McClain nominated him for the award, writing in the application that Sonnier is a dedicated employee who has taught himself many of his skills. “Without formal train-ing, he learned to use the computer, enter and summarize data and use applicable scientific equipment such as electronic meters, data loggers, spectrophotometer and chemical analysis kits.”
“I like the science, and learning from the studies and the outcomes,” Sonnier said. “Every year it’s different.”
The crawfish work is done on the station’s South Farm, and Sonnier said he likes the quiet surroundings.
He is looking forward to the new installation of a dozen tanks, 5 feet high and 12 feet in diameter, to conduct research projects.
Sonnier’s wife, Donna, also works at the station.
Sonnier said he enjoys the simpler aspects of life, growing a garden and spending time with his family, a stepson and a daughter. “Just the little simple things for me mean a lot.”
Bruce Schultz [email protected]
Sonnier to Reach 20-year Mark at Station
Visit the LSU AgCenter online store at the following website:
https://store.lsuagcenter.com/
