Superior leaf physiological performance contributes to sustaining the final yield of cotton (Gossypium hirsutum L.) genotypes under terminal heat stress

Abstract

This study aimed to optimize methods for identifying heat-tolerant and heat-susceptible cotton plants by examining the relationship between leaf physiology and cotton yield. Cotton accessions were exposed to elevated temperatures through staggered sowing and controlled growth conditions in a glasshouse. Based on their yield performance, leaf physiology, cell biochemistry, and pollen germination, the accessions were categorized as heat-tolerant, moderately tolerant, or susceptible. High temperatures had a significant impact on various leaf physiological and biochemical factors, such as cell injury, photosynthetic rate, stomatal conductance, transpiration rate, leaf temperature, chlorophyll fluorescence, and enzyme activities. The germination of flower pollen and seed cotton yield was also affected. The study demonstrated that there was a genetic variability for heat tolerance among the tested cotton accessions, as indicated by the interaction between accession and environment. Leaf gas exchange, cell biochemistry, pollen germination, and cotton yield were strongly associated with heat-sensitive accessions, but this association was negligible in tolerant accessions. Principal component analysis was used to classify the accessions based on their performance under heat stress conditions. The findings suggest that leaf physiological traits, cell biochemistry, pollen germination, and cotton yield can be effective indicators for selecting heat-tolerant cotton lines. Future research could explore additional genetic traits for improved selection and development of heat-tolerant accessions.