Department of Crop Botany, Bangladesh Agricultural University, Mymensingh, Bangladesh.
Three cultivars of rice were studied under natural day length with normal night temperature, short day (10 hours) and low night temperature (16°C) and long day (16 hours) and high night temperature (35°C). The plant height and panicle length were found to be reduced while fertile tillers, fertile grains, 1000-grain weight and chlorophyll contents were found to be increased under long day with high night temperature in all cultivars. The growth parameters like CGR, ROR, NAR and LAI increased in BR 8 while only LAI increased in BR 3 and both RGR and LAI were found to be increased in BR 6 under long day with high night temperature. The relationship between biological and economic yield were found significant.
