Terminal Heat Stress in Wheat: Impacts and Solutions

Wheat (Triticum aestivum L.) is recognized as one of the most significant cereal crops worldwide. A major challenge to wheat production is heat stress, an abiotic factor that significantly diminishes grain yield, particularly in semi-arid and subtropical regions. Heat stress poses severe threats to wheat growth, with yield losses estimated at approximately 6% for each 1°C increase in temperature. Terminal heat stress, which becomes critical when the average temperature during the grain-filling phase surpasses 31°C, is a primary factor contributing to reduced productivity. The elevated temperatures experienced during this crucial developmental stage are the primary drivers of low wheat yields. During the 2020-21 and 2021-22 growing seasons, the average temperatures in March and April were 2-3°C higher than usual, exacerbating the impact of terminal heat stress. Consequently, wheat yields were reduced by 2-3 quintals per acre. The sudden increase in both maximum and minimum temperatures across North-West India contributed to an 8-10% reduction in final crop yields during these years. This review summarized the general effect and management to this problem. Findings indicated that elevated temperatures accelerated wheat maturation, leading to earlier-than-normal harvests. On March 15 of both consecutive years, maximum temperatures reached 40°C and remained at or above this threshold throughout the harvesting period. To mitigate the effects of heat stress, several strategies were employed, including the development of heat- resistant crop varieties, the adoption of climate-adaptive cropping practices, the implementation of conservation agriculture, and adjustments to planting windows. Researchers can use this review to better understand the landscape of terminal heat stress research and shortcomings.