Genetic analysis for yield and its components in cotton by generation mean analysis method

Background and Purpose: Understanding inheritance patterns, gene action types, and effective breeding strategies is crucial for improving agricultural traits. Generation mean analysis is a powerful method for assessing genetic parameters and heritability of traits. This study was designed to investigate the genetic parameters involved in the inheritance of morphological traits and yield components in four cotton cultivars through generation mean analysis.
 
Materials and Methods: To analyse the genetic inheritance of traits, P1, P2, F1, F2, BC1, and BC2 generations were produced in 2020-2021. These generations were evaluated in 2022 using a randomized complete block design with three replications across three regions. After performing analysis of variance and identifying significant differences among generations, genetic analysis was conducted using the Method of Jinks and Hayman with three- and six-parameter models. The means and standard errors for each trait were calculated across the different generations.
 
Results: The variance analysis revealed significant differences among regions and cultivars. At Hashemabad, the Armaghan variety yielded the highest, whereas at Karkandeh and Darab, the Golestan variety was superior. No significant differences were found among generations in terms of plant height, number and length of reproductive branches, and number of bolls. However, significant variations were observed for boll weight, lint percentage, yield, and earliness. The lowest boll weight, lint percentage, and yield were associated with the green seed parent (P1). The F2 progeny exhibited the highest yield, averaging 2899 g/plot, which may be attributed to its genetic diversity. Additionally, performance differences between the green seed parent and the white seed parent were evident.
 
Conclusion: The superior performance of progenies relative to their parents suggests the presence of a dominance effect in controlling these traits. For boll weight and number of reproductive branches, both additive and dominance × additive effects are significant. The prominence of the additive effect indicates that selection and self-pollination are effective breeding methods for these traits. In contrast, traits such as lint percentage were more influenced by dominance × dominance interactions, indicating potential double epistasis effects. The dominance variance exceeded the additive variance, and the degree of dominance was greater than one, suggesting that selection alone may be inadequate. Therefore, hybridisation may be a more effective approach for achieving breeding objectives for these traits.