Effect of Heat Stress on Rice and Its Management

Abstract

Rice is a major staple food, consumed by more than half of the world’s population and providing 20% of calories consumed worldwide. However, rice production is under serious threat due to rapid increase in the earth’s rising temperatures. Heat stress (HS) destroys the physiological processes like seed germination, photosynthesis, respiration and plant growth. HS also has detrimental effects on the plant root system that provides water uptake, nutrient uptake and supports other parts of the plant, leading to disruption of root growth and development, as well as decrease in shoot and root fresh, and dry weight. As a result there is a drastic reduction in the yield and quality of the grain. HS affects all the growth stages of rice. However, the reproductive phase of rice is more sensitive to HS than other stages. Most agronomic management approaches concentrate on early sowing, site-specific cropping and irrigation system changes, and adoption of a late or early maturing cultivar to avoid high temperatures during grain filling to combat HS. Growth regulators such cytokines, salicylic acid, and ethylene precursors can also be used to treat rice plants suffering from HS related damage such as pollen abortion, decreased spikelet’s per panicle and kernel weight, and low seed-setting rate. In numerous rice cultivars, exogenous treatment of spermidine boosted photosynthetic and antioxidant capability and partially reduced the yield penalty brought on by HS. Developing germplasm with higher tolerance to climate-induced stresses through breeding is a sound climate change or abiotic stresses adaptation strategy. Higher thermo-tolerance may be induced by choosing cultivars that flower in the early morning before the temperature rises and have larger anthers with long basal pores, higher basal dehiscence, and pollen viability. Breeding rice varieties tolerance to high temperature has so far received little attention as compared to other abiotic stresses like drought and salinity. Therefore, there is an urgent need to explore the breeding aspect for heat tolerance in rice varities for better management of loss due to heat stress.