Salinity stress is a major constraint in the upland cotton (Gossypium hirsutum L.) productivity, particularly at the seedling stage, where ion toxicity, osmotic imbalance, and oxidative damage severely impair early growth. This study dissected salt tolerance mechanisms across 20 diverse cotton genotypes subjected to three salinity stress levels: control (1.6 dS/m), moderate (12 dS/m), and severe (17 dS/m). Plants, evaluated at the fourth true leaf stage, had their key morphophysiological and biochemical parameters checked. Elevated salinity significantly reduced shoot and root biomass, while sodium accumulation and Na⁺/K⁺ ratios sharply increased, indicating disrupted ionic homeostasis. For plants to cope with this stress, antioxidant enzyme activities—superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)—markedly rose, reflecting activation of ROS detoxification pathways. The principal component analysis (PCA) differentiated tolerant and sensitive genotypes by integrating multiple traits. CIM-595, Mubarak, CIM-612, and FH-152 were distinct as tolerant genotypes with balanced ionic profiles and elevated antioxidant responses, whereas sensitive lines, such as SB-149, KZ-181, and AGC-999, performed poorly under severe salinity. These findings provide mechanistic insight into cotton’s adaptive strategies and offer robust targets for breeding programs in saline-prone agroecosystems.
Cotton (G. hirsutum L.), salinity, seedling stage, salt tolerance, PCA, morphophysiological and biochemical traits
This study identified salt-tolerant cotton (G. hirsutum L.) genotypes through principal component analysis, which identified CIM-595, Mubarak, CIM-612, and FH-152 as salt-tolerant genotypes. These lines maintained balanced Na⁺/K⁺ ratios and elevated antioxidant enzyme activities, indicating effective ionic regulation and oxidative stress mitigation. Their performance under high salinity supports their use in breeding salt-resilient cotton.