Inheritance of seed physical traits in upland cotton under different temperature regimes

Abstract

Physical seed traits such as seed weight, volume and density are determinants of seed vigour in cotton, while seed surface area is of prime importance in lint production. Two Pak-upland cotton crosses, plus their parental, F2 and back cross generations were evaluated over two years to determine the inheritance pattern of their seed physical traits under heat stress and non-stress field regimes. The heat stress regime suppressed the average expression of seed traits in all generations. The results showed there to be low genetic variability with respect to physical seed traits, particularly seed volume, seed density and seed surface area, among several generations of the two cotton crosses. The inheritance of seed physical traits was complex in both crosses due to the presence of substantial non-allelic interactions (digenic epistatic effects) and the influence of generation x temperature regime interaction. The two crosses expressed different patterns of inheritance for seed physical traits. Those governing seed volume and seed surface area were highly sensitive to the temperature regime in both crosses and were controlled by additive genetic effects under heat stress conditions, and by dominant genetic effects under non-stress regime. The non-stress regime favoured the expression of dominant genetic effects. From a breeding point of view, the heat stress regime could be a more favourable environment for enhancing selection efficiency.