Water and fertility management of rice varieties under low atmospheric evaporative demand

Abstract

SUMMARYFour soil moisture and two nitrogen levels were combined in eight treatments to study moisture and nitrogen effects on Dular (June–September crop) and Patnai-23 (June–November crop) varieties of rice. Both the varieties when grown under natural precipitation yielded significantly less than at other moisture levels. Whereas there were no significant differences amongst the three treatments of submergence (15–10 cm), cyclic submergence (15–0 cm) and cyclic wetting-drying (saturation to field capacity) for Dular rice, the former two treatments proved better than the latter for Patnai-23 rice. Dular responded to the treatments of cyclic wetting-drying in a way similar to that of submergence because the crop completed its life cycle during the period of low evaporative demand. Among the levels of nitrogen, 40 kg N/ha proved optimum for Dular rice and 6O kg N/ha for Patnai-23 rice. The increase in yield of grain was associated with increase in the number of panicles, number of spikelets/panicle and percentage of ripened spikelets. The concentration of N, P, Fe and Mn in the plant was maximum under submergence followed by cyclic submergence, cyclic wetting-drying and natural precipitation. Higher levels of nitrogen increased only N and P contents in the plant.