| Fifteen F1 combinations crossed among 5 naturally colored cotton and 1 fiber white cotton different in yield components or fiber quality parameters according to half diallel crossing design (6X5/2) were used to evaluate the genetic effects of seed index, lint index, lint percentage and fiber quality. The experiment data processing was conducted by using additive-dominant genetic model (Zhu, 1997). The main results were as follows:1. The lint index, lint percentage and fiber length of naturally colored cotton were mainly controlled by the additive effects and could be improved by selection in early generations. We can take advantage of the high heterosis in selecting the combinations since the seed index was mainly controlled by dominant effects. While the fiber strength, the uniformity ration, the fiber elongation and micronaire were controlled by additive effects and dominant effects equivalently, which would affect the selection effects in early generations and the improvement would be better for these traits by selecting in later generation. The heritability of naturally colored cotton yield components were 27.19%(seed index)~80.85%(lint percentage) and fiber quality parameters were 9.58%(fiber elongation)~87.01%(fiber length).2. Zixumian and Cai 8 had positive GCA effects for fiber length, fiber strength and fiber elongation, therefore, these two varieties were the better parents for significantly increasing the fiber quality of progenies of naturally colored cotton. The parent of Cai 9-1 couldn't decrease the fiber quality except fiber length. Hongyezongxu was the parent for no-insignificantly decreasing the yield components of Fl. The parent of fiber white cotton with high quality fiber property could improve yield and fiber quality of colored cotton hybrid. Zixumian X Cai9-1, Hongyezongxu X Cai8, hongyezongxu X Emian3, Cai8 X Cai9-land Cai8 X Emian3 were considered promising combinations for fiber quality which had significant positive SCA effects. These varieties and combinations could be used in breeding of naturally colored cotton and the hybrid according to the different breeding goals.3. The genetic materials of naturally colored cotton with high seed index and lint percentage might have high seed yield and lint yield which could be improved by selecting yield components except seed index that was negative covariance with yield. The positive genetic covariance between seed index, lint index and lint percentage could help breeders to improve these traits simultaneously. The relationships among uniformity ration, fiber strength and fiber length with positive additive correlations mainly could mainly be used in indirect selection of colored cotton breeding. The breeders could select simultaneously fiber length and fiber strength in a range of Micronaire. The negative genetic covariance was found between fiber quality parameters and yield components. But the negative additive covariance were no-significant between uniformity ration and seed yield, fiber elongation andyield, Micronaire and yield, and this result demonstrated there wasn't affection between each other in these five paired traits. It might decrease the yield of naturally colored cotton by selecting high fiber length and fiber strength.4. In white fiber cotton and colored cotton crosses, the estimated surpassing parental Fl heterosis values for fiber length were all reached above -10% and the positive mean parents heterosis values were not significant. However, fiber strength showed significant surpassing parental Fl heterosis over the better parent based on population in the mass of combinations, even surpassed the parent with white fiber in some combinations. The differences between the estimated heterosis values for Micronaire were due to the different combinations. It was shown clearly that the Fl combinations crossed between parents with similar performances had relatively high dominant effects and significant positive Fl surpassing parental heterosis, while no Fl combination crossed...
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