Influence of Night Temperature on Rice Yield and Quality

Abstract

Rice is an important food crop for a substantial proportion of the human population and due to the risks posed by global warming and climate change, there is significant interest in analysing the effects of environmental factors such as temperature on rice yield and quality. Compared to studies on the influence of day temperatures on rice yield and quality, there are fewer studies on the influence of night temperature on these parameters. Any change in ambient temperature is known to activate stress-associated signalling pathways in plants. Night temperature is a crucial environmental factor that affects metabolic processes such as respiration and translocation of nutrients. An increase in night temperature reduces rice yield by reducing the translocation of non-structural carbohydrate and nitrogen which ultimately reduces grain-filling rate, grain weight and quality. Other parameters such as the percentage of chalky rice kernels are also adversely affected by an increase in night temperature. High night temperature (HNT) increases spikelet sterility, thereby decreasing pollination. At the cellular level, high night temperature decreases membrane thermal stability and increases the rate of respiration. Treatment with exogenous effectors such as salicylic acid reduces the effects of high night temperature by increasing the total anti-oxidant capacity and membrane thermal stability. An increase in Ca signalling proteins and heat shock proteins (HSPs) also enhances tolerance to high night temperature. This chapter therefore focuses on the overall influence of night temperature on rice physiology, grain yield and the endogenous signalling events.