Grain Growth and Endosperm Cell Size Under High Night Temperatures in Rice (Oryza sativa L.)

Abstract

Background and Aims High night temperatures are more harmful to grain weight in rice than high day temperatures. Grain growth rate and growth duration were investigated to determine which was the cause of the decrease in final grain weight under high night temperatures. Endosperm cell number and cell sizes were also examined to determine which might cause the decrease in final grain weight.Methods Rice plants were grown outdoors in plastic pots and moved at heading time to three temperaturecontrolled glasshouses under high night temperature (HNT; 22/34 C), high day temperature (HDT; 34/22 C) and control conditions (CONT; 22/22 C). Grains were sampled periodically, and the time-course of grain growth was divided into rate and duration by logistic regression analysis. Endosperm cell numbers and cell sizes were analysed by digitalized hand-tracing images of endosperm cross-sections.Key Results The duration of grain growth was reduced by high temperature both day and night. However, the rate of grain growth was lower in HNT than in HDT. The number of cells in endosperm cross-sections in HNT was similar to that in HDT, and higher than that in CONT. The average cell area was smaller in HNT than in either CONT or HDT. The differences in average cell areas between HNT and HDT were greater at distances 60-80 % from the central point of endosperm towards the endosperm surface.Conclusions The results show that HNT compared with HDT reduced the final grain weight by a reduction in grain growth rate in the early or middle stages of grain filling, and also reduced cell size midway between the central point and the surface of endosperm.ª 2005 Annals of Botany Company

Rice yields in tropical/subtropical Asia exhibit large but opposing sensitivities to minimum and maximum temperatures

“…Despite these methodological differences compared with previous studies, our findings corroborate recent ones that T min has a large, negative impact on yield (8,30). Although the mechanisms responsible for the negative impact have yet to be conclusively identified (4), our results could be explained by increased respiration losses during the vegetative phase (8) and reduced grain-filling duration and endosperm cell size during the ripening phase (31).…”

Application of DSSAT Crop Simulation Model to Estimate Rice Yield in Keonjhar District of Odisha (India) under Changing Climatic Conditions

“…As compared to maximum temperature, increase in minimum temperature had more pronounced negative impacts on Swarna yield. This more pronounced negative impact of minimum temperature on rice yield could be explained by increased respiration losses during the vegetative phase (Peng et al, 2004) and reduced grain-filling duration and endosperm cell size during the ripening phase (Morita et al, 2005).…”

Influence of Low/High Temperature on Water Status in Developing and Maturing Rice Grains

“…They apprehended that these high temperature injuries were due to disappearance of enzyme activity relating to starch synthesis of the grains. Furthermore, Morita et al (2005) reported that high night temperature (22/34ºC, day/night) induced higher reduction of fi nal grain weight and growth rate of rice in early-and mid-stage of grain fi lling along with the reduction of cell size compared with high day temperature (34/22ºC, day/night). Moreover, the rice grain grown at 38/21ºC temperature contained more chalky grains (Lisle et al, 2000).…”