Study on Phenotypic Diversity of Salix paraplesia Natural Populations in Northwest Sichuan

Salix paraplesia is a native shrub species in northwest Sichuan Province. The leaf phenotypic variation extent and variation laws of five male and female S. paraplesia populations in Aba Prefecture, Sichuan, were studied by using the coefficient of variation, nested analysis of variance, cluster analysis, and correlation analysis to reveal the genetic variation laws of Salix paraplesia natural population. The phenotypic diversity among and within the populations were also analyzed. The results showed that there was great diversity with the leaf phenotypic traits of S. paraplesia both within and among the natural populations in this region. The average variation coefficient of leaf phenotypic trait was 18.97%, the phenotypic differentiation coefficient among the male and the female populations was 21.5% and 21.32% individually, which were lower than those within the populations. It was showed that the diversity of leaf phenotypic traits among populations was higher than that within the populations. The leaf phenotypic coefficient of the studied populations dropped from ‘Baxi’ (19.49) to ‘Hongxing’ (19.42),‘Rangtang’ (19.05),‘Aba’ (18.94) and ‘Hongyuan’ (17.98). It was showed that the phenotypic diversity of ‘Baxi’ population was the highest, while the phenotypic diversity of ‘Hongyuan’ population was the lowest. The result of UPGMA cluster analysis for the five male and female populations by calculating euclidean distance among the populations showed that the male and female populations could be clustered into three groups.