Hybrid rice: achievements and outlook
1989
Yuan, Longpin | Virmani, S.S. | Mao Changxiong (Hunan Hybrid Rice Research Center, Changsha, Hunan (China))
Extensive research on and development of hybrid rice in China have clearly demonstrated its usefulness in significantly increasing rice yields beyond the levels of improved semidwarf varieties. Hybrid rice is currently planted on a 9 million ha in China. Several International Rice Research Institute (IRRI)[Los Banos, Laguna (Philippines]-bred cultivars are used as male parents of commercial varieties. Research at IRRI and in several collaborating countries shows that hybrids have yields 15-20% higher than those of the best semidwarf varieties. Hybrid varieties suitable for other countries are still in the pipeline. In addition to higher yield, heterotic rice hybrids show higher productivity per day, adoptability to certain stress environments, and better utilization of applied nitrogen fertilizers. Hybrid rice seed production technology has been well developed in China, and prospects for its adoption outside China appear promising. A number of cytoplasmic male sterile (CMS) lines developed and used in China are not adoptable outside China for lack of adequate disease and insect resistance and acceptable grain quality. Several CMS lines developed at IRRI are now being evaluated in collaborating countries. Both China and IRRI are involved in research to diversify CMS sources, to prevent genetic vulnerability problems in hybrid varieties. Sufficient numbers of restorer lines are available among indica rice cultivars, but restorer numbers are negligible in japonica rices. By selecting appropriate CMS and restorer lines, hybrids possessing multiple disease and insect resistance and desired grain quality can be developed. Constraints and the outlook for hybrid rice technology are also discussed.
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