Abstract: Five cottonseed quality traits were analysed by Hayman’s diallel genetic model with Griffing’s diallel crossing system ? of six parents.The results indicated that cottonseed protein content and index,oil content and index, and seed kernel index all conformed to "additive-dominant" model. Seed protein content and index had very important dominant effect and expressed superdominance. Cottonseed oil content and index had very important additive effect and expressed incomplete dominance. Seed kernel index had more important additive and dominant effect and closely approach complete dominance. The frequencies and directions of dominant and recessive genes, the ratios of positive and negative genes, and the narrow inheritability of various traits were obviously different within researched parents.

Key words: Upland cotton (G. hirsutum), Quantitative inheritance, Cottonseed quality, Diallel genetic analysis