RICE RATOONING - IRRI books - International Rice Research Institute

Use of ratooning in hybrid riceJ. S. ChauhanCentral Rainfed Rice Research Station, Post Box 48Hazaribagh 825 301, Bihar, India.ABSTRACTThe adoption of hybrid rice depends on the relative cost of the hybrid seed versus theeconomic gain obtained by cultivating a hybrid instead of a nonhybrid variety. A ratooncrop has short growth duration and low production costs and needs less irrigationwater. Ratooning male-sterile, maintainer, and restorer lines would result in increasedseed yield that could help reduce initial seed cost. Ratoon cropping then might alsocompensate for the extra cost of hybrid seed. The ratooning ability of 57 hybrids and5 check varieties was evaluated in the 1983 dry season at IRRI; 14 hybrids and IR56performed consistently well. Hybrid IR19657-34-2-2-3-3A/IR36 showed the highestregeneration and had the most tillers and panicles/m 2 . Selecting parents with goodratooning ability is suggested for hybrid rice breeding programs.Because there is little possibility for bringing more land under cultivation, cropintensification and higher yields seem to be the only research avenues open forscientists to bridge the increasing gap between food production and food demand.The world will need 30% more rice in the next decade; that rice has to be produced onthe same amount of land. Higher yields can be obtained by adopting improvedproduction technology — high yielding varieties and efficient use of land, waterresources, fertilizers, and pesticides for better crop management.Hybrid rice has a great potential for increasing rice productivity in certainareas. The success of hybrids in China encouraged the International Rice ResearchInstitute (IRRI) to revive research on hybrid rice in 1979 (1) and to explore itspotential and problems outside China. Several national rice improvement programsin India, Indonesia, Thailand, Bangladesh, Pakistan, Philippines, and the Republicof Korea have also shown interest in hybrid rice production technology (4).The success of hybrid rice and its acceptance by farmers usually depends onthe relative cost of the hybrid seed versus the economic gain obtained by cultivating ahybrid instead of a nonhybrid variety (4). Hybrid seed yields are very low (0.45-1.5 t/ha) in China. At IRRI, hybrid seed yields ranged from 0.02 to 0.62 t/ha in thewet season and 0.04 to 1.58 t/ha in the dry season (Table 1) (2).Seed production depends on environment, management levels, male-sterilelines, and synchronization of A and B lines in the CMS reproduction plot. Suchintensive efforts for such low seed yield result in high seed cost, estimated to be3-4 times higher than seed costs of conventionally bred varieties.