The LSU AgCenter has recently released two new rice varieties that should give a boost to Louisiana rice production. Both of these varieties contain the gene for resistance to imadazolinone (imi) herbicides, which will allow them to be used with the Clearfield production system. The Clearfield system is based on technology developed from research conducted at the Rice Research Station beginning in the 1990s. This technology allows for the chemical control of red (weedy) rice in a rice production field, which was not possible prior to the introduction of Clearfield rice. Red rice is a noxious weed in rice production and is a close genetic relative of commercial rice, actually belonging to the same taxonomic species (Oryza sativa) as cultivated rice. Because they are so closely related, it is extremely difficult to develop a herbicide that will kill red rice without injuring commercial rice if used in the same field. Through mutation breeding, rice lines were developed that were resistant to the imi herbicides. Since these mutants were developed, rice breeders at the station have developed and released 11 Clearfield varieties that contain the resistance gene and can be used with the Clearfield system.

Clearfield technology has dramatically improved the yield as well as quality of the rice produced on many Louisiana rice fields and has been widely used by Louisiana rice producers, accounting for more than 60 percent of the 2015 Louisiana rice acreage. However, the rice breeding program is continually working to develop new, superior Clearfield varieties to improve the viability of the Louisiana rice industry. These two new varieties should do just that because they both have shown improved performance over current Clearfield varieties.

CL153 is a semidwarf, early-maturing long-grain Clearfield variety with excellent grain yield, good grain quality and very good resistance to blast disease. In multiyear, multilocation testing, CL153 has shown per acre average yields within 200 pounds of CL151, which has the highest yield potential among current Clearfield pureline varieties. However, CL151 is very susceptible to blast disease, which is common in Louisiana rice production in some years. CL153 has good resistance to blast disease. The new variety also has better overall grain appearance and better resistance to lodging than CL151. Compared to CL111, the most widely grown Clearfield pureline variety, CL153 has shown an approximate 500-pound-per-acre yield advantage, as well as superior blast resistance. The length of the growing season for varieties is especially important in southwest Louisiana where second crop production is a crucial part of the rice-growing system. CL153 is similar in maturity to CL151 and about four days later than CL111, which gives it a good growing cycle for the region. All of these varieties are similar in plant height, but CL153 has shown somewhat better resistance to lodging than CL151. The new variety, while showing good resistance to blast disease, is susceptible to sheath blight and moderately susceptible to bacterial panicle blight, cercospora and straighthead. CL153 was selected from the cross 9502008-A//AR-1188/COCODRIE/3/CFX 26/9702128/4/CHENIERE, which was made at the Rice Research Station in 2011. The line was developed from the bulk of a single F₃ line (13P1442) made at the Puerto Rico winter nursery in 2013. CL153 has typical long-grain cooking quality and grain cereal chemistry characteristics.

CL272 is the other new release. This variety is a semidwarf, early-maturing medium-grain Clearfield experimental rice line with excellent grain yield and good grain quality. CL272 has averaged an approximate 300-pound average yield per acre advantage over CL271, the current highest yield potential Clearfield medium-grain. The new variety also has much better grain quality than CL271, which should provide a significant advantage for the Louisiana rice milling industry and medium-grain end users. CL272 and CL271 are very similar in maturity, plant height, lodging susceptibility and disease resistance to the major Louisiana rice diseases. The new variety has typical medium-grain cooking quality, grain dimensions and cereal chemistry characteristics. CL272 was selected from the cross Neptune//Bengal/CL161, which was made at the Rice Research Station in 2009. The variety was developed from the bulk of a single F₃ line (11-38915) made at the Rice Research Station in 2011.

Both of these varieties were developed in a relatively short period of time – six and a half years for CL271 and four and a half years for CL 153, both from cross to release. This was only possible through extensive use of the breeding program’s winter nursery facility near Lajas, Puerto Rico. Both varieties were grown in foundation seed production fields at the Rice Research Station in 2015. In 2016, acreage seeded to the two new varieties will be devoted primarily to registered and certified seed production. Certified seed of both should be readily available in 2017.


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

Permission granted November 15, 2015 by B. Leonards (LA Farm & Ranch) to republish article on www.lsuagcenter.com.