THE EFFECT OF HEAT STRESS ON PEROXIDASE ACTIVITY AND COTTON MORPHOLOGY

Abstract

High-temperature stress is a major abiotic factor that adversely affects plant growth and development, particularly in cotton (Gossypium spp.). This study aimed to investigate the impact of heat stress (45°C for 6 hours) on peroxidase enzyme activity and morphological traits in two cotton cultivars: Surkhan-103 (conventionally bred) and Ravnaq-1 (developed through marker-assisted selection). The results demonstrated a significant increase (27.7%) in peroxidase activity in the heat-tolerant Surkhan-103 cultivar, while a sharp decline (40%) was observed in the Ravnaq-1 cultivar, indicating its susceptibility to elevated temperatures. Morphological analyses further confirmed these differences, with Surkhan-103 maintaining growth parameters under stress, while Ravnaq-1 exhibited reductions in plant height, root length, and biomass. These findings highlight the physiological and biochemical basis of heat tolerance in cotton and provide valuable information for breeding programs targeting climate-resilient cultivars.