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Breeding for adaptation to rainfed Ecologies
Excessive and continued research attention given but inevitable for sustaining the high productivity level of irrigated rice, as many perceive, has been at the expense of equally large and potential rainfed ecology. Accounting for over 55% of the rice area, the ecology characterized by varied water regimes viz rainfed shallow lowland, (14 million ha) rainfed upland (4 million ha) and deepwater (1 million ha), remains still, the most handicapped with yields less than one half of what is being harvested in irrigated ecosystem. Efforts of decades to evolve ideal high yield varieties adapted to one or the other yield depressing abiotic stresses viz drought, submergence, flash floods and problematic soils characteristic to these ecologies, have been only a futile exercise. Whereas pureline selections from well adapted native varieties have been meeting the varietal needs of semideep and deepwater ecologies, medium late maturing semitall and semidwarf spillovers from irrigated ecology have been catering to the needs of favourable shallow lowlands. CR 1014, Mahsuri, Pankaj, Swarna, Savithri, Ranjit, Kanak etc. popular for decades in shallow lowland ecology are all from irrigated ecology. Continued breeding efforts, especially the shuttle breeding programmes have led to the evolution of progressively improved varieties like Gayathri, Puja, Varshadhan, Swarna Sub IA, CR Dhan 401 etc and hybrids like Jayalakshmi and Ajay for this ecology. Breeding for rainfed uplands although has not as yet led to ideal varieties, good number of early maturing varieties combining limited tolerance to moisture stress such as Annada, Adithya, Govind, Kalinga III, Vanaprabha, PNR 381, Vandana etc satisfy to a great extent, the varietal need of rainfed uplands. As for problem soils about 6.75 million hectares of rice area are suffering from coastal (2.96 million ha) and inland (3.8 million ha) salinity. Unlike the area under coastal salinity that remains practically static, sodicity is on the increase largely because of defective irrigation-drainage system in the irrigation commands and deltas. Varietal remedy although found to an extent through development of salinity tolerant high yielding varieties like CSR 12, CSR 30, CSR 27, CST 7-1, Jarva, DRR Dhan 39, Luna Sampad, Narendra Ushar Dhan 8002 etc, the problem is still not addressed to desired level.