Oxidative stress caused by the accumulation of reactive oxygen species (ROS) produces harmful toxic effects on plant cells and exposes the cotton crop to high temperatures, which are the major limiting factors causing yield losses. Every cotton genotype under heat stress, the pro/antioxidant being a key system among the biochemical factors contributing to plant protection, entailed studies in two cotton cultivars, Surkhan-103 (G. barbadense L.) and Bukhara-102 (G. hirsutum L.) in the laboratory and field conditions. The antioxidant enzyme activities, including superoxide dismutase (SOD), catalase (CAT), peroxidase (PO), malondialdehyde (MDA), and proline, underwent evaluation under prolonged (6-hour) exposure to high temperature (45 °C). The results revealed cultivars Surkhan-103 and Bukhara-102 are classifiable as resistant to heat stress by their biochemical parameters; an increase in the concentrations of hydrogen peroxide and MDA with activities of antioxidant enzymes could become the key markers of plant tolerance and intolerance to heat stress. Under high-temperature conditions, the fine-fiber cultivars Surkhan-104 and Surkhan-103, the medium-fiber cultivars Bukhara-102, S-6577, and S-6585, and the advanced lines L-688, L-214, and L-403 exhibited considerable stability. These heat-tolerant genotypes achieved recommendation for use in future breeding programs aimed at improving stress resilience.
G. barbadense and G. hirsutum, hyperthermia, malondialdehyde (MDA), superoxide dismutase (SOD), peroxidase, reactive oxygen species (ROS), proline
The study comprising the hyperthermia effect on cotton (G. barbadense and G. hirsutum) cultivars revealed significant insights into plant responses to heat stress. Both cultivars demonstrated resilience by maintaining higher activities of key antioxidant enzymes under prolonged exposure to high temperatures.