Evaluation of salt tolerance in cotton (Gossypium hirsutum L.) seedlings using the multitrait genotype-ideotype distance index (MGIDI)

Cotton is a vital agricultural crop and a primary source of natural fibres, linters and oil. However, soil salinity poses a major abiotic threat to crop productivity worldwide, particularly in arid and semi-arid regions. Although cotton is considered moderately salt-tolerant, its early growth stages are highly sensitive to stress. This study evaluated the morphological response of 28 cotton cultivars to controlled salt stress conditions. Results revealed a clear, dose-dependent reduction in seedling growth under increasing salinity levels. Analysis of variance (ANOVA) confirmed a significant cultivar × treatment interaction (PC × PT), highlighting substantial genetic variability and contrasting responses of cultivars to salinity. Pearson correlation analysis indicated stronger relationships between linear growth traits and biomass accumulation under saline conditions, suggesting a coordinated adaptive modulation of growth mechanisms. Principal component analysis (PCA) confirmed the dominant effect of salinity on phenotypic variability and distinguished distinct adaptive growth strategies among cultivars. The multitrait genotype-ideotype distance index (MGIDI) effectively identified the cultivars Bukhoro-14 (C5), C-4727 (C7), Kelajak (C14) and Nasaf (C19) as genotypes with enhanced salt tolerance at specific levels of induced salt stress. These genotypes represent valuable genetic resources for breeding programs aimed at developing salt-tolerant cotton cultivars suited to arid environments.