Classification evaluation and fiber quality characteristics of different types of cotton varieties using similarity-difference analysis method

For an accurate analysis of the regional distribution characteristics, the fiber quality traits of 531 candidate varieties in national cotton regional trials in China between 2005 and 2014 were analyzed to achieve comprehensive evaluation of hybrid and conventional cotton varieties by using similarity-difference analyses method in crop-breeding fields. The results showed that:1) conventional cotton varieties with fiber quality qualified as type Ⅰ, type Ⅱ, and type Ⅲ accounted for the total conventional varieties of 1.58%, 28.42%, and 14.74%, whereas the proportions of type Ⅰ, type Ⅱ, and type Ⅲ for hybrid cotton were 0.59%, 19.94%, and 10.56%, respectively. The identical degree of the conventional and hybrid cotton cultivars in the Yellow River Valley (YeRV) was estimated to be 0.869 3 and 0.888 8, the identical degree of hybrid cotton in the Yangtze River Valley (YaRV) was 0.864 3, and that of cotton varieties in the Northwest Inland (NWI) was 0.890 5. 2) The fiber quality of conventional cotton in the NWI was better than that of hybrid cotton in the YeRV, and the fiber quality of the latter was better than that of conventional cultivars in the YeRV and hybrid cotton in the YaRV. There were no significant differences in conventional cultivars in the YeRV and hybrid cotton in the YaRV. The YaRV is suitable cotton planting area for medium-long length and high-strength of fiber, and high-micronaire hybrid cotton varieties. The NWI is suitable for planting high-quality conventional cotton varieties with long and fine quality as cotton spinning high yarn industry base. In brief, the fiber quality traits of conventional cotton in the NWI were proven to have the most potential, which can be an important reference value to optimize high-quality cotton regional layout and to adjust the planting structure in China.