Genetic Diversity of the Upland Cotton Varieties Bred in North Xinjiang Region Revealed by Agronomic Phenotypes

We attempted to reveal the genetic background and phenotypic characteristics of the varieties bred in Northern Xinjiang through the study on genetic diversity of the 38 cultivated varieties approved in Xinjiang. The results showed that the trait of the fruit branch number in the 13 tested phenotypic traits had the highest genetic diversity index; along with the year in different breeding period, the bred cotton varieties exhibited that the growing period gradually shortened, fruit-branch number increased, cotyledon node and plant height significantly increased; and boll weight per boll obviously increased, seed index also showed an upward trend with boll weight changes; the boll number per plant and lint percentage also presented overall increasing trend, however, the lint percentage left a great space to be enhanced; the fiber length and strength gradually increased in the bred varieties, and micronaire values showed a downward trend. Overall the quality traits went to be reasonable with each passing periods. Genetic analysis indicated that 38 domestic bred varieties could be clearly divided into two groups with similar phenotypic traits, similar genetic background, the same breeding unit and the same type varieties were better clustering together. The clustering results would be relatively accord with the evolution trend in their real characteristics and genetic background. Overall, the domestic bred varieties had become major cultivating varieties in Northern Xinjiang, The reason would lie in the reasonable utilization of the genetic composition from the American components and the Yellow River cotton germplasms as well as Liaomian cotton series of special early maturing cotton area, which would provide insights, basis and developing direction to break out the genetic component narrow issues in Xinjiang cotton breeding program.