Analysis on Combining Ability and Heterosis for Yield and Its Properties of Excellent Naturally Brown Varities(Lines) in Upland Cotton (Gossypium hirsutum L.)

The crosses were made by using natural coloured brown cotton to analyze high parent heterosis,mid-parent heterosis and competitive heterosis and combining ability effects for yield characters and component of yield.The results showed that all yield traits were mainly controlled by the additive effects and by domaint effects.The GCA(general combining ability)and SCA(specific combining ability) variances were significant at 1% level for seed cotton yield,boll weight and seed index.The SCA variances of lint yield were significant at 1% level.The GCA variances were significant at 1% level for lint percentage and boll number per plant.The heterosis of yield component was boll number per plant,boll weight and lint percentage in descending order.The average mid-parent heterosis of yield character had positive heterosis at 1% level.The lint yield of F1 generation was significantly increased by more than 22% and genetic colour and lustre were stable.