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.