Influence of weather parameters on growth and yield of kharif rice grown under varying transplanting dates

摘要

Results of field experiment, conducted with four dates of transplanting for two successive years during kharif season, revealed that dry matter production, number of panicles m~(-2), filled grains panicle and grain yield were higher in crops transplanted by 24 July, beyond which the values of these parameters decreased. Increasing temperature range during reproductive and ripening phases enhanced spikelet sterility and thereby reduced grain yield of late-transplanted crops. Durations of vegetative, reproductive and ripening phases were lengthened with delay in transplanting. The increased durations with delay in transplanting among different phases are associated with lower maximum and minimum temperatures. Accumulated values of temperature range during reproductive and ripening phases showed significant positive correlation, and GDD and PTU during reproductive phase showed significant negative correlation with spikelet sterility. Maximum and minimum temperatures, temperature range and SSH during vegetative phase showed significant negative correlation, whereas minimum temperature, GDD and PTU during reproductive and ripening phases had significant positive correlation with dry matter production at harvest. During reproductive phase, minimum temperature, GDD and PTU had significant positive, and temperature range and VPDII exhibited significant negative correlation with number of filled grains per panicle, whereas higher temperature range and SSH during ripening phase were associated with lower number of filled grains per panicle. Higher VPDII and PTU during vegetative and reproductive phases decreased yield, but higher GDD during reproductive phase helped increase grain yield. Higher minimum temperature, GDD and PTU during reproductive and ripening phases were associated with greater number of panicles per square metre. Coefficients of determination of multiple regression equations for filled grain percentage, test weight, grain yield and total dry matter at harvest were able to account for 98, 96, 86, 96 and 80 % of total variation, respectively.