Effect of heat stress on yield and economics of rice (Oryza sativa L.) cultivars under different sowing dates
S.MOHAPATRA, S.K.TRIPATHY*, A.K.MOHANTY and S.TRIPATHY
An experiment was carried out during rabi 2017-18 and 2018-19 at Regional Research and Technology Transfer Station, Chiplima, Sambalpur, Odisha of Odisha University of Agriculture and Technology to study the influence of temperature stress at different sowing dates to on yield attributing characters, yield and economics of rice (Oryza sativa L.) cultivars. Rice sown on 10th December utilized more thermal and heat units as compared to 30th December and 10th January sown crop. The differential yield response of cultivars to various sowing dates was found to be due to their differential tolerance against high temperature at reproductive growth phase. On an average, 15.7 to 25% reduction in rice yield was obtained in case of sowing dates where temperature stress coincided with reproductive growth phase. The crop sown on 10th December took maximum growing degree days units to attain different phenological stages till physiological maturity. Number of grains panicle-1 and rice yield increased with delay in sowing time up to 30th December, whereas there was a decrease in duration and tillers m-2. December 30 sown rice registered the highest grain yield (7.3 t ha-1), grain yield heat use efficiency (3.2 kg ha-1 0C day-1) and dry matter heat use efficiency (6.8 kg ha-1 0C day-1). Maximum number of grains panicle-1, grain yield, grain yield heat use efficiency, dry matter heat use efficiency and benefit cost ratio of rice cultivar MTU 1156 sown on 30th December seems to be associated with non-coincidence of their reproductive growth period with heat stress and seedling growth periods with cold stress. Cultivar MTU 1001 showed moderate tolerance to temperature stress and thus recorded lower heat susceptibility index (0.65) and higher yield stability ratio (84.5).