High-temperature scalding

High-temperature scalding is a physiological disorder in plants caused by excessive heat exposure and intense solar radiation. Unlike infectious diseases, this condition occurs due to thermal stress when the plant's physiological cooling mechanisms, primarily transpiration, fail to compensate for the rapid rise in cellular temperature.

This condition frequently affects major field crops, with maize being particularly susceptible during its peak vegetative stages and pollination. High temperatures can cause cellular damage, leading to localized death of leaf tissues, which significantly hinders the plant's ability to produce energy through photosynthesis.

The primary symptoms include the sudden appearance of bleached, papery, or light-brown lesions on the leaves. These patches are often irregular in shape and may appear on the upper canopy first, as these parts receive the highest amount of solar energy and are exposed to the hottest air layers.

The development of this disorder is heavily linked to environmental conditions, specifically prolonged dry spells combined with extreme heatwaves. When soil moisture is depleted, the plant cannot maintain the necessary moisture flow to the leaves, leading to dehydration and subsequent thermal scorching of the cellular structures.

The economic impact is significant, as severe scalding leads to reduced grain fill, lower test weights, and overall yield loss. To mitigate these effects, farmers should focus on agrotechnical practices such as selecting heat-tolerant hybrids, optimizing plant density to allow for better air circulation, and utilizing biostimulants that help crops manage stress more effectively.