The Bases of Decrease in Rice Productivity Due to Global Warming.

The presence of seasonally high nighttime temperatures (HNT) along the Gulf Coast, occurring during the critical stages of development, could reduce rice yield and quality. The objective of this study was to determine the effects of HNT and plant growth regulators (vitamin E, glycine betaine [GB], salicylic acid [SA]) on growth, development and physiology of rice plants. Plants were grown under ambient nighttime temperature (ANT) (27 ^oC) and HNT (32 ^oC) in the greenhouse. They were subjected to a HNT through use of continuously controlled infrared heaters. Nighttime temperatures were imposed from 2000h until 0600h. The results indicated no effects of HNT on photosynthesis; however, HNT increased respiration rates, decreased membrane stability, pollen germination, spikelet fertility, grain length, width, and weight. In addition, HNT hastened the crop development rate, as indicated by the dates of panicle emergence. All the above parameters contributed towards decreased rice yields under HNT. Rice plants treated with GB or SA showed an increase in yield compared to untreated plants, when grown under ANT and HNT.