Evaluation of diversity and effective traits in Iranian cotton germplasm.

Drought is one of the most important abiotic factors influencing crop development and productivity. As a result, there is a need to enhance cultivars with high compatibility and low water requirements. This study examined the genetic variation of drought tolerance as well as the morphological, physiological, and agronomic aspects of cotton (Gossypium hirsutum L.) germplasm. For this reason, sixty-four genotypes of cotton were selected and cultivated in the field for two years under two moisture regimes, including normal and drought stress. All of the evaluated variables showed considerable genotypic variation between genotypes, indicating a great potential for trait improvement through focused selection in breeding programs. Drought stress has a detrimental influence on the majority of the assessed characteristics, reducing their genotypic variation. In both locations, most examined characteristics had quite high heritability estimates under both situations, indicating the presence of some important genes or QTLs influencing them. Principal component analysis revealed a negative association between earliness and photosynthetic and yield-related traits, indicating that selection for early maturity may reduce productivity. This suggests that selecting for earliness in cotton can decrease output. Contrasting genotypes identified by biplot analysis can be used to develop breeding populations for drought-tolerance studies.