Response of two rice (Oryza sativa) hybrids to graded levels of nitrogen

A field experiment was conducted during wet season of 1993 and 1994 to study the effect of 5 nitrogen levels (0, 50, 100, 150 and 200 kg/ha) and 2 rice (Oryza sativa) hybrids 'PHB 71' and 'PMS2A/IR31802'). The results revealed that the hybrid 'PHB 71' seedlings were more vigorous than the 'PMS2A/IR31802' in terms of dry weight, shoot length and vigour index. There was a significant increase in grain yield with each additional application of nitrogen from 0 - 200 kg/ha during 1993 while in 1994 the increase in N dose from 150 - 200 kg/ha could not register significant increase. Hybrid 'PHB 71' gave 0.75 and 0.95 tonnes/ha higher yield than 'PMS2A/IR31802' in 1993 and 1994 respectively. The highest level of yield 9.25 and 8.24 tonnes/ha was recorded by 'PHB 71' at 200 kg N/ha during the respective year. Yield attributes showed improvement with the increase in N level.