Update on Hybrid Rice Research

Dr. Jim Oard evaluating hybrids at the H. Rouse Caffey Rice Research Station.

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The LSU AgCenter’s H. Rouse Caffey Rice Research Station was established in 1909 and is now well into its second century of providing new technology to the Louisiana rice industry. The station was established primarily to provide improved varieties for the Louisiana rice industry. While its mission has expanded over the past 100 plus years, new variety development remains a core objective of the facility.

The station has been successful in variety development efforts, having released 52 varieties, including 32 in the past 25 years. In fact, the station has recently released two new varieties, CL153, a Clearfield long-grain and CL272, a Clearfield medium-grain.

Historically, all of the varietal research has been focused on the development of pureline varieties. By definition, a pureline variety is developed by increasing the self-fertilized progeny (or offspring) from a single true-breeding plant. This means that seeds harvested from planting a pureline variety can be planted the following generation and produce the same genetic population (or the same variety).

A different approach to improving rice genetically is through the development of rice hybrids. Hybrid seed is actually the F1 seed of a cross between two different genotypes. The F1 hybrid of crosses between different genotypes is typically much more vigorous than its parents. This hybrid vigor, or heterosis, can be manifested in many ways, including increased rate of growth, earlier flowering and increased yield – the last being of greatest importance in rice production.

Hybrid rice has been developed and has demonstrated significant yield advantages over inbred varieties since the 1970s. By employing Chinese germplasm, RiceTec has successfully commercialized hybrid rice production in the southern United States in recent years. Since the early 2000’s, hybrid rice has accounted for an increasing percentage of southern U.S. rice acreage.

In 2008, the LSU AgCenter entered into a research agreement with the Guangxi Academy of Agricultural Sciences, which is located in Nanning, China. Through this agreement the Rice Station was able to obtain cytoplasmic (CMS) A/B lines, thermo- and photoperiod-sensitive sterile S lines and a number of restorer R lines. With these important hybrid breeding lines in hand, AgCenter scientists initiated research into hybrid rice development in 2009. Previous research suggested that the pureline varieties or advanced experimental lines that are continuously developed at the Rice Station can serve as critical materials for the development of hybrid rice. By incorporating important hybrid rice traits (especially sterility and/or fertility) from obtained germplasm into adapted elite Louisiana materials – or even direct test-crossing between male sterile lines and Louisiana cultivars or lines – AgCenter scientists are aiming to develop adapted hybrids with competitive yield, good milling and acceptable grain quality.

The goals of this research include: 1) development and identification of male sterile lines (cytoplasmic A or environmental sensitive S) and restorer (R) lines adapted to southern U.S. environmental conditions; 2) identifying elite cross combinations through the extensive test-crossing; 3) exploring the feasibility of economical hybrid seed production; and 4) development of a marker-assisted selection scheme involving identifying and developing molecular markers for sterility/fertility traits, as well as anther culture, to significantly expedite the breeding process.

Dr. Jim Oard has directed the hybrid breeding research activities since 2012, and the program is making rapid progress. Much of the focus has been on modifying the initial male sterile lines received from China to be more adapted to Louisiana rice growing conditions. Additionally, work is ongoing to incorporate the Clearfield and Provisia resistant genes into adapted male sterile lines. Another research focus has been identification of Louisiana-adapted germplasm that will serve as successful restorer lines. Of prime importance in Dr. Oard’s program is developing potential commercial hybrids with good grain quality. Historically, U.S. rice hybrids have shown very good field yields but substandard grain quality.

This ambitious research endeavor is beginning to pay dividends. Yield trials in 2015 identified several experimental hybrids with yield potential comparable to the best current commercial hybrids but with superior grain quality. Some of these hybrids also possess the Clearfield trait and, if released, could be used with that technology. It is important to recognize that this is long-term research. However, we are hopeful that within two to three years, we can provide a high-yielding, high-quality hybrid to the Louisiana rice industry, which was developed at the Rice Research Station.

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

Permission granted December 15, 2015 by B. Leonards (LA Farm & Ranch) to republish article on www.lsuagcenter.com.
12/15/2015 8:33:33 PM
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