Genetic analysis of yield and yield-related traits in short-season cotton (Gossypium hirsutum L.)

Six short-season cotton cultivars (Gossypium hirsutum L.) were crossed in a diallel crossing system to evaluate inheritance and interrelationship of phenotype and genotype of yield and yield-related traits (cottonseed yield, lint yield, cottonseed yield before frost, lint yield before frost, lint percentage, boll weight and boll number) and their correlation with earliness traits. The study was carried out from year 2005 to year 2008. The experiment design was a randomized complete block design with three replications. Additive, dominance and epistasis effects were analyzed with ADAA model. The results showed that yield and yield-related traits were mainly controlled by dominant genetic effects and also had a definitely proportion additive by environment interaction effects. Cottonseed yield, lint yield, cottonseed yield before frost, boll weight, lint percentage, boll number and lint yield before frost had the highest broad sense by environment interaction heritability (HBE) estimates, 0.653, 0.602, 0.600, 0.528, 0.416, 0.387 and 0.324, respectively. Lint percentage, cottonseed yield, lint yield and cottonseed yield before frost had higher narrow sense by environment interaction heritability (HNE), 0.416, 0.301, 0.263 and 0.185, respectively. Only boll weight and boll number had the highest narrow sense heritability (HN), 0.345 and 0.139, respectively. Some F₁ hybrids had positive significant heterozygous dominance effects. Some F₁ hybrids had significant positive epistatic effects and affected by environment. Among yield and yield-related traits, they all had significant positive genetic and phenotypic correlation, excepting lint percentage and boll weight, boll weight and boll number had significant negative genetic and phenotypic correlation. Yield and yield-related traits had a negative correlation with earliness traits except lint percentage and boll number. Lint percentage with harvested rate before frost, date of first square and number of node first sympodial branch, boll number with yield and relative traits showed significant negative genetic correlation. The results showed that the higher the lint percentage, boll weight and boll number and the higher harvested yield and the later the maturing. Based on these results, it is suggested to selection of yield and yield-related traits should be undertaken at late generation (F₄, F₅), and early-maturing parents A₁, B₁, B₂ and B₃ could be used to improve yield and yield-related traits in short-season cotton breeding programs.