New rice varieties flourish in deep waters
IN THE flood-prone areas of eastern Uttar Pradesh, Bihar, West Bengal and Orissa -- where many believe rice originated -- yields are only about one-fifth that of Punjab and Haryana because the rice spends most of its energy literally trying to keep its head above water and has only a little left to produce grain. Consequently, the yield from the rice grown in these parts rarely reaches one tonne per ha, as compared with the five to six tonnes per ha that is the norm in Punjab and Haryana.
However, new varieties of deep-water rice with substantially higher yields have been developed, report G Singh, O P Singh, P Singh and R K Mehta of the Crop Research Station at Ghagharaghat in Bahraich district (Indian Farming, Vol 41 No 10).
Of 12 varieties developed, a type called Jalamagna (immersed in water) was recently released in Uttar Pradesh. This variety grows upto three metres tall, can subsist on little water in its early stages and produces yields of upto 4.2 tonnes per ha, which compares better with the Punjab-Haryana yield. Another new variety, NDGR 402, yielded an average of 4.9 tonnes per ha over three years.
Though deep-water rice is usually broadcast, that is thrown across the field, the scientists found that sowing it behind a plough increased the yield nearly 10 per cent and sowing with a seed drill raised it by 15 per cent. The scientists also report that if the seed is sown at the right time, the quantity required is much less. The optimum rate for broadcasting is 120 kg of seed per ha, but for plough sowing it is only 100 kg and for drill sowing, just 80 kg.
Though deep-water soil is highly fertile, the scientists say applying urea granule fertilisers, which release nitrogen slowly, increases the yield.
Deep-water rice is normally grown as a monocrop. However, if maize is intercropped with rice in the 95-day period after the rice is sown and before water floods the field again, the individual crop yields were found to be lower than if they were cultivated as single crops. But the combined yield and the income to the farmer from the double crop were higher, the scientists report.