Abstract
High night-temperature often leads to a decrease in grain yield of rice. We examined the effects of night temperature on yield of a large-grain rice cultivar, Akita 63. Plants were grown under two different night-temperatures for 45 days after flowering, 27˚C/27˚C (day/night) as high night-temperature (HNT) and 27˚C/22˚C (day/night) as the control. The dry weights of brown rice and filled spikelets were decreased by 8% and 9% in the HNT plants, respectively. Total dry-weights of the whole-plant at 45 days after flowering showed no significant difference between the treatments. Ratio of panicle dry weight to total biomass in the HNT plants was higher than in the control. This suggested that decrease in the grain yield in the HNT plants is due to changes in biomass allocation at the level of the whole-plant.
