Estimation of hybridisation and heterosis in some upland cotton lines by crossing North Carolina II

Cotton is an important fibre crop worldwide. TheHigh yield is the ultimate goal of a breeding program in cotton. In order to achieve this goal, the production of hybrid cultivars is an important step in increasing production The yield potential of current cotton genotypes can be increased through hybridisation. However, the development of superior hybrids with high yield and better fibre quality requires knowledge of the mode of inheritance and the nature of genetic control of traits. Therefore, genetic analysis plays an essential role in breeding through hybridisation. In this study, the North Carolina II mating design was used to cross 5 maternal and 2 paternal parents to produce 10 intraspecific hybrids. The F1 hybrids were grown together with the parents in the 2021 growing season in a randomized block design at the Karkandeh Research Station of the Cotton Research Institute of Iran. The results of the analysis of trait variance show that there is a significant difference between the genotypes and hybrids studied. Therefore, an estimate of combinability was made to determine the genetic components of the North Carolina II split. The proportion of overall combinability in the traits studied was higher than their private combinability, indicating a greater contribution of additive effects than dominance effects in the genetic control of these traits. For the traits number of reproductive branches, boll weight and strength, the private heritability was 0.75, 0.68 and 0.62, respectively, indicating the involvement of dominance effects in the inheritance of these traits. The role of additive effects in the inheritance of the traits elasticity and uniformity of fibres shows the effect of selection to improve these traits. Among the different hybrids, the highest yield was observed in the cross of Maxa × SKSH 249, which can be attributed to the genetic distance between the two genotypes. Considering the greater contribution of additive effects in the inheritance of performance traits and performance components, using the selection method to improve these traits is the better method. Considering that both additive and dominant effects play a role in the inheritance of fiber quality, it appears that if the aim of the breeder is to improve fiber quality, the use of selection and hybridization methods may be fruitful. These results provide a basis for accelerating the development of high-yielding hybrids in upland cotton.