Terminal Heat Stress and Its Mitigation Options through Agronomic Interventions in Wheat Crop: A Review

Climate change will be one of the most critical dangers to agriculture in the coming years. On average, abiotic stresses account for 50% of the production losses in agricultural production. Terminal stress is a major environmental issue limiting wheat production in the majority of wheat-growing regions across the world. The term "terminal heat stress" refers to a rise in temperature (> 30°C) after anthesis during grain development which impairs the process of grain filling in wheat. Rising temperatures shorten the vegetative and reproductive periods of the wheat crop, but the reproductive stage is more vulnerable than the vegetative. The major portion of India, including the north-eastern plain zone, the central zone, and the peninsular zone, experienced terminal stress over the summer. There are numerous solutions available for mitigating the harmful effects of terminal heat stress on wheat crops. Adjusting sowing time is one of the most impactful agronomic techniques. Wheat planting methods such as conservation tillage, bed sowing, conventional tillage plus mulch, and surface residue preservation are considered suitable alternatives for mitigating terminal stress. Moreover, irrigation at a critical period reduces terminal heat stress and boosts wheat grain development. Foliar spraying of osmoprotectants such as KNO3, Thiourea, Zn, and many others during anthesis and post-anthesis can also help in alleviating the effects of high-temperature stress on wheat crops.