RICE RATOONING - IRRI books - International Rice Research Institute

Potential for rice ratooningin eastern India,with special referenceto photoperiod-sensitive ricesfor deepwater areasS. K. Bardhan Roy and J. MondalRice Research Station, Chinsurah-712 102West Bengal, IndiaandB. N. Chatterjee, S. Bhattacharya, P. Debnath, and B. MondalBidhan Chandra Krishi Viswa Vidyalaya, Kalyani-741 235West Bengal, IndiaABSTRACTRatooning photoperiod-sensitive rice varieties in deepwater areas of eastern India mayreduce crop loss from frequent floods or rainwater accumulation. Rice varietiessuitable for these areas should have photoperiod sensitivity, semidwarf plant type withelongation ability or flood tolerance, fertilizer responsiveness, tolerance for moisturestress, and good ratooning ability. In experiments at Chinsurah and Kalyani, WestBengal, India, the ratoon crop of photoperiod-sensitive rice grown in the dry seasonyielded well in the wet season. The F 2 segregates of a few crosses indicated that ratooncharacters may be accumulated in high yielding varieties. Although the ratoon cropyielded less than the main dry season crop, its growth and yield were equal to those of anormally sown crop in the wet season. Maximum yields of main crop and ratoon cropwere obtained when complete fertilizer was applied at 100 kg N, 22 kg P, and 42 kgK/ha. Cold temperatures in December reduced yields of the wet season ratoon cropharvested from November to February.Rice cultivation on 1,599,000 ha of lowland deepwater areas (70-100 cm) in easternIndia is unpredictable because sudden floods or water accumulation damages thecrop in various growth phases. Ratooning of photoperiod-sensitive rice varieties,which can be grown twice a year in identical photoperiods, may greatly reduce thecrop loss on about 500,000 ha. A suitable ratoon variety for the area should have thefollowing characteristics (1):• photoperiod sensitivity with a high yielding background,• fertilizer responsiveness with main crop yield of 4-5 t/ha in the dry season,• photoperiod-sensitive ratoon that remains in the vegetative stage from Aprilto August,• good ratooning ability and vigorous growth during premonsoon rains,• some degree of drought and submergence tolerance or elongation ability forthe ratoon, and• resistance to viral diseases.