Field Day Rice Breeding Highlights

Steve Linscombe

LSU AgCenter

H. Rouse Caffey Rice Research Station/Southwest Region

The 2017 LSU AgCenter H. Rouse Caffey Rice Research Station Field Day was held on June 28. This was the 108th field day since the station was established in 1909. Weather was unusually mild with lower than normal temperatures. The number of participants on the field tours was excellent with well over 400, and the tour provided an excellent overview of ongoing research at the station.

Dr. Adam Famoso and I spoke at the rice breeding stop. I discussed a new variety and a potential release. PVL01 is the newly released variety that will be the initial variety used with the new Provisia herbicide resistance system. This an early long-grain, short-stature variety with good yield potential and milling yields as well as excellent grain appearance characteristics. The line typically has very low grain chalk numbers and very long kernel length, averaging over 7.2 mm. The variety is susceptible to blast disease and moderately susceptible to sheath blight. PVL01 is currently being grown on over 600 acres of seed production in Louisiana (over 1,200 throughout the southern U.S.) and should be available for limited commercial production in 2018. Provisia will be a new herbicide resistance system similar to the Clearfield system but based on a different chemistry. It will allow for the control of red rice and other grass weeds in a rice production system. The new system will allow for cleaning up weedy rice in fields where the Clearfield technology is no longer effective because of outcrossing and volunteers. In addition, having a second herbicide resistance system in rice should allow for systematic rotation in the future, which should prolong the overall herbicide resistance technology.

A Clearfield Jazzman line (CLJ027) was also discussed. The line has very good yield potential (better than Jazzman and Jazzman 2) and excellent grain quality and aroma. CLJ027 is currently being grown in a six-acre foundation field by Mr. Rick Zaunbrecher and could be released for 2018 production. The two newest Clearfield long-grain varieties (CL153 and CL172) were also discussed. CL153 (a Louisiana release) has shown yield performance similar to CL151 but with much better resistance to blast disease, better resistance to lodging and less grain chalk. CL172 (Arkansas release) has shown good yield potential, excellent grain quality and good blast resistance. Also discussed were new releases from neighboring states: long-grains Diamond (Arkansas) and Thad (Mississippi) and medium-grain Titan (Arkansas). These three lines have all done well in Louisiana testing. Also discussed were advanced experimental lines in the breeding program including Clearfield, Provisia and conventional long and medium grains as well as specialty types.

Dr. Famoso discussed several areas where the high-throughput, single nucleotide polymorphism (SNP) DNA marker lab has been integrated into the breeding program at the station. Over the last year, efforts have focused on discovering, developing and validating new markers for key traits, such as blast and Cercospora resistance, grain quality traits and herbicide resistance. In addition, a set of 12 markers that creates a genetic profile fingerprint that can differentiate any two varieties from each other has been identified. Throughout the last eight months, efforts have begun to apply these markers to breeding and foundation seed efforts. This includes testing all seed sources going into foundation seed headrows to identify potential off-types, outcrosses or other impurities before these are planted. This has already proven effective in cleaning up some material that had some impurities present, and it is anticipated that it will also reduce the work load required for rouging of off-types in the foundation fields in the future.

Another use of this technology is the incorporation of novel blast resistance into elite lines. These efforts include crossing three new blast resistance genes from exotic, un-adapted lines into three elite LA varieties (CL272, CL153 and Mermentau). Each of these genes alone has been previously demonstrated to confer resistance to all U.S. blast races. However, the varieties these genes were in are not desirable to use as parents for developing new elite varieties due to poor grain quality, agronomics, etc. To facilitate rapid introduction of these genes, the program has developed DNA markers to track each of the genes and use this to continuously cross them into elite lines. The markers will allow for the selection of desired plants based on the DNA, rather than conducting phenotyping in the field.

Another important use of this system is in early generation breeding selections, which allows for evaluating plants at the beginning of the breeding pipeline for traits that typically could not be screened for at this stage. Since October 2016, over 20,000 new experimental lines have been screened for multiple blast resistance genes, grain quality genes and herbicide traits. Only the selected plants are then advanced for the typical screening in the field. This allows for an increased frequency of plants in the field that meet the desired level of disease resistance, grain quality, etc. It also provides flexibility in new breeding crosses that are made when developing new conventional rice varieties. This is because it allows for crossing a Clearfield line to a conventional line and selecting for non-Clearfield types based on the DNA marker profile. These lines can then be tested as part of the conventional breeding efforts.

This project was partially supported by USDA National Institute of Food and Agriculture.

Permission granted July 15, 2017 by B. Leonards (LA Farm & Ranch) to republish article on www.lsuagcenter.com.

Drone photo of Rice Breeding stop on 2017 Rice Field Day.