Effects and Management Practices of Heat Stress in Maize (Zea Mays L.): A Review

Abstract

A vital crop in various agro-ecological regions, Maize (Zea mays L.) ranks second only to rice in terms of cultivation in Nepal. Although Maize is considered heat resistant, exposing it to the temperature exceeding 37-degree Celsius results in the heat stress reducing its productivity. Threat of global warming is real with the changing climate, studies indicate future heat waves will likely be more severe and persistent, negatively impacting the productivity. Reduced plant height, decreased leaf area, and delayed flowering are some of the consequences of heat stress in maize plants. It disrupts photosynthetic efficiency, damaging photosynthetic machinery, reducing enzyme activity, and impairing chloroplast functioning. Furthermore, heat stress induces ROS causing cell membrane damage, disruption of enzymatic activities, ultimately resulting in stunted plant growth and productivity. During the flowering stage, heat stress reduces the number of florets, impairs silk and grain development, and promotes premature senescence, leading to a shorter plant lifespan and decreased grain yield. Early sowing of maize, effective irrigation and nutrient management can help reduce soil temperature, enhance water use efficiency and minimize heat stress. The adoption of heat-resistant maize varieties and improved breeding techniques is also essential for mitigating the adverse effects of heat stress in maize cultivation. This paper addresses the consequences of heat stress on maize, including effects on growth, photosynthetic characteristics, reactive oxygen species (ROS), reproductive development, premature senescence, and overall grain yield while also exploring strategies for mitigating the impacts of heat stress on maize through agronomic practices and breeding.