Evaluation And Genetic Diversity Analysis Of The Derived Lines From Cotton Comprehensive Population In Yellow River Basin

Cotton is one of the most important economic crops, as well as the important strategic material in China. Main objective of the breeding for cotton varieties is selecting plants with the excellent comprehensive characters, such as high-yield, good-quality, resistance to disease and insects and so on. The breeding of new varieties is dependent on the characteristics of excellent germplasm resources. But genetic diversity level of the cotton germplasm resources is relatively low in china, with narrow genetic background.In this study,37excellent lines derived from a comprehensive population of Yellow River Basin, were evaluated in the improvement effect and the genetic diversity. They also could be excellent resources for conventional breeding in Changjiang River Basin.1. There were significant differences in yield and yield components among the derived lines. Comparing with the control variety Ekangmianl3, there were21derived lines whose lint yields were increased. Two derived lines U-16and U-30,118.75Kg/667m2and116.02Kg/667m2respectively, had higher lint yields at a very significant level, belonging to the high-yielding germplasm resources. There were three derived lines U-23, U-26and U-34whose lint yields were increased significantly. There were16derived lines whose lint yields reduced with no significance. In general, these derived lines were improved much in yield potentials.In boll weight, there were only three derived lines U-21, U-36and U-2, whose boll weight were heavier than the control variety, but with no significance. The derived line U-21had the heaviest boll weight of5.55g. The rest of34derived lines showed lighter in the boll weight.7derived lines reduced very significantly and4lines reduced significantly in boll weight. This indicated that these derived lines had nagetive improvement effect on the boll weight.In lint percentage, the derived line U-16had the highest lint percentage of45.50%at a very significant level, belonging to the high lint percentage germplasm.27derived lines showed lower in lint percentage. There were9derived lines whose lint percentage reduced very significantly, and5derived lines whose lint percentage reduced significantly. This indicated that these derived lines did non have an good performance in lint percentage.The derived lines U-30and U-3had more bolls than the control variety at a significant level in bolls number. There were11derived lines, which had less bolls at a non-significant level. There were no differences between the derived lines and control variety in boll number.2. The variation of the fiber quality of the derived lines was small, with the average of variation coefficient of3.24%. The derived lines U-34, U-3, U-37, U-7, U-2and U-1exhibited excellent fiber quality in general.3. The variation of agronomic traits in ascending order by coefficient of variation of these traits was:Fiber uniformity index> Length> Micronaire> Elongation> Fiber strength> Plant branch numbers> Lint percentage> Plant height> Boll weight> Seed index> Lint index> Boll> Lint yield. Compared to fiber quality, main agronomic traits had greater variation.4. The resistances to Verticillium dahliae were quite different among the derived lines.7derived lines showed good resistance, belonging to the type of resistance (R level). They were the derived lines U-6, U-7, U-16, U-25, U-26, U-29and U-31respectively.16derived lines belonged to the type of tolerance (T level) in resistance, the control variety Ekangmian13also belonged to this type with the relative disease index of24.64.5. The factor analysis of the derived lines was performed on14agronomic traits. The result showed that the first7common factors were chosen and their cumulative variance contribution rate reached83.08%. The former5common factors were fiber quality factor, plant type factor, factor of yield factor, disease index factor and comprehensive factor of fiber quality and yield, with their contribution rates of28.45%,15.50%,12.07%,8.87%and6.95%respectively.6. Clustering analysis of Derived lines and10cotton varieties from the Yangtze River Basin:10cotton varieties from the Yangtze River Basin were distributed in three groups, but8cotton varieties were in group Ⅱ.Their genetic relationships were close, with narrow genetic background. Most of the derived lines were concentrated in groups I, which were different from the cotton varieties from the Yangtze River Basin. This indicated that there was a clear distinction between the two basins cotton varieties.37derived lines from the comprehensive population of the Yellow River Basin were dispersed in seven groups. The range of variation of genetic similarity coefficient was large between37derived lines with a large range of wide genetic background.