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.

培育耐盐基因型（salt-tolerant genotypes）对于最大化盐碱地（salinized land）的作物生产潜力至关重要。为评估耐盐性相关遗传多样性，本研究在17 dS m⁻¹盐胁迫条件下，采用20项与耐盐性相关的农艺与生理性状，对35份具有遗传多样性的棉花种质（cotton accessions）开展了筛选试验。广义线性模型（General Linear Model）分析结果显示，供试种质均受到显著的盐胁迫影响，且所有检测参数的基因型×处理互作效应均达显著水平。在全部35份供试种质中，CCB-1、CCB-2、CCB-28、CCB-3、CCB-4、Ghauri-1、JSQ-70及JSQ-71等基因型在盐胁迫下的株高、单株结铃数、铃重、衣分、籽棉产量与纤维品质性状上均表现出优异性能。生理性状方面，盐胁迫环境下叶绿素（chlorophyll）、类胡萝卜素（carotenoid）含量、可溶性总蛋白、K⁺及K⁺/Na⁺比值均显著降低；而过氧化氢酶（catalase）、超氧化物歧化酶（superoxide dismutase）、过氧化物酶（peroxidase）、过氧化氢（H₂O₂）及丙二醛（MDA，malondialdehyde）含量等生化指标则显著升高。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及CCB-28等基因型的农艺-生理与纤维品质性状指标均处于较低水平，表明其对盐胁迫敏感；盐胁迫下，这类种质的抗氧化水平下降，而K⁺/Na⁺比值、Na⁺、过氧化氢及丙二醛含量则显著升高。而CCB-5、CCB-6、CCB-7、CCB-8、CCB-9、CCB-10、CCB-11、CCB-12、CCB-13、CCB-14、CCB-15及CCB-16等基因型在盐胁迫下的相关性状表现则处于中等水平。本研究通过多元分析技术（聚类分析与主成分分析（Principal Component Analysis, PCA）），基于供试性状将35份基因型划分为3个类群：盐胁迫耐受型（类群1）、中度耐受型（类群2）与盐胁迫敏感型（类群3）。