Harnessing genetic diversity in cotton for enhanced resilience against salt stress by using agro-physiological characters

Creating salt-tolerant genotypes is crucial for maximizing the productivity under salinized land. To evaluate genetic diversity for salt tolerance, 35 diverse cotton accessions were screened under 17 dS m⁻¹ salt stress conditions using 20 agronomic and physiological traits relevant to salt tolerance. The general linear model analysis indicated significant salinity impacts across the studied accessions, and genotype × treatment effects were also significant for all parameters examined. Among all 35 studied accessions; the genotypes CCB-1, CCB-2, CCB-28, CCB-3, CCB-4, Ghauri-1, JSQ-70, and JSQ-71 showed considerably higher performance for plant height, boll per plant, boll weight, lint percentage, seed cotton yield and fiber quality traits under salt stress. Physiological traits, chlorophyll and carotenoid contents, total soluble proteins, K⁺, and K⁺/Na⁺ were reduced under saline conditions, while biochemical traits such as catalase, superoxide dismutase, peroxidase, H₂O₂ and MDA level increased. The genotypes CCB-17, CCB-18, CCB-19, CCB-20, CCB-21, CCB-22, Hatf-3, Badar-1, Eagle-2, Eagle-4, CCB-23, CCB-24, CCB-25, CCB-26 and CCB-28 exhibited lower values for agro-physiological and fiber quality character respectively, signifying their sensitivity to salt stress. Under salinity, these genotypes showed reduced antioxidant levels and increased values for K⁺/Na⁺, Na⁺, H₂O₂, and MDA contents. Whereas the genotypes CCB-5, CCB-6, CCB-7, CCB-8, CCB-9, CCB-10, CCB-11, CCB-12, CCB-13, CCB-14, CCB-15, and CCB-16 demonstrated moderate performance for these traits under salt stress conditions respectively. Utilizing multivariate analysis techniques (cluster and PCA), 35 genotypes have been categorized into three groups based on studied traits: tolerant (cluster-1), moderately tolerant (cluster-2), and susceptible (cluster-3) under saline conditions.