Genetic basis of variation for within-boll yield components in cotton

Cotton productivity on a per-hectare basis is low in Pakistan. As boll is the basis for seed cotton yield, within-boll yield components can potentially serve as the most basic determinants of cotton productivity on a per unit land area basis. Before attempting the improvement of any trait, it is necessary to know the genetic mechanism lying behind its inheritance. The current study aimed to estimate the genetic basis of within-boll yield components in cotton. The research trials were conducted at the research area of the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan. Epistasis was found to be involved in all traits such as average boll weight, seed number boll-1, seed mass boll-1, lint mass boll-1, lint mass seed-1, seed index, seed volume 100-seeds-1, seed density, and surface area seed-1. Additive variance was greater in magnitude than dominance variance for traits such as lint mass boll-1 and lint mass seed-1 in cross I and for seed number boll-1, seed mass boll-1, and lint mass seed-1 in cross II. The magnitude of both variances was nearly equal for seed density in cross I and seed number boll-1 in cross II. While dominance variance was found to be greater in magnitude than additive variance for all the remaining traits in both crosses, the degree of dominance ?(H/D) in cross I was partial for lint mass boll-1 and lint mass seed-1. We found complete dominance for seed density and overdominance for the remaining traits. While in cross II the degree of dominance was partial for seed mass boll-1 and lint mass seed-1, complete dominance was found for seed number boll-1 and overdominance for the remaining traits.