Response of winter rice to different water regimes and nitrogen levels

Abstract

A sutudy was conducted at the Agrnomic Research Station, Chalakudy for three consecutive winter (second crop) seasons from 1983-84 to 1985-86 to study the effect of different water regimes and nitrogen levels on the growhth and yield of short duration rice variety Triveni. Four water regimes (continuous submergence of 5±2 cm and 7<cm irrigation after one, three and five days of the disappearance of ponded water) and four levels of nitrogen (0, 35, 70 and 105 kg N/ha) in factorial combinations constituted the treatments. The study indicated that irrigation for rice during the second crop season is to be scheduled five days after the disappearance of ponded water at a depth of 7 cm especially when the ground water table is shallow and the evaporative demand of the atmosphere is low. This schedule saved approximately 70 per cent of the irrigation water used to maintain continuous submergence without any appreciable reduction in grain and straw yields. Application of 70 kg N/ha recorded the maximum grain yield among the nitrogen levels. The response equation was quadratic in nature. The physical optimum dose of nitrogen was found to be 88.2 kg/ha. The response to nitrogen application was not influenced by the variation in irrigation management.