Cotton (Gossypium spp.) is a vital raw product for the global textile industry. Its production is affected by salt stress. This study was designed to investigate the morph-physiological and biochemical responses of cotton genotypes to salt, aiming to identify mechanisms of salt tolerance and susceptibility. Within a glasshouse, diverse genotypes were grown in polythene bags filled with sand, subjected to three salt stress levels i.e., control, moderate stress (12dS/m), and severe stress (17dSm), in a two-factor factorial design under a Completely Randomized Design (CRD). Physiological measurements and biochemical assays under varying salt conditions revealed significant decreases in growth related traits (shoot and root lengths, fresh and dry weights) with increased salt severity. Alongside antioxidant defense mechanisms were upregulated, as evidenced by increased peroxidase (POD), catalase (CAT), superoxide Dismutase (SOD) activities, and proline levels, indicating adaptive responses to oxidative stress. Principal Component Analysis (PCA) showed the results for that the first two principal components accounted for approximately 76% of the variance, summarizing the major contribution by genotypes' salt responses. Cluster analysis further delineated the genotypes into three clusters, representing distinct salt response strategies. This study revealed the complex dynamics between cotton's genetic makeup, physiological responses, and biochemical processes in facing salt conditions and to ascertain the salt tolerant and susceptible genotypes.

Keywords: Cotton, salt stress, seedling, morpho-physiological, biochemical, proline, catalase