Breeding implications from a diallel analysis in two environments of yield and component characters in upland cotton (Gossypium hirsutum).

In a full diallel set of crosses involving nine Albar 51 lines the genetic control of yield and yield components were largely accounted for by additive effects, although non-additive effects were evident. Significant differences in correlation coefficients between sites and the interaction of genetic effects indicate the effect of the environment on development and gene action. The failure to achieve yield improvements appears to stem from a combination of testing at the early selection stage in a single environment and of a narrow genetic base. The implications for future breeding programmes are discussed.