Analysis of phenotypic diversity in pods and seeds traits of natural populations of Gleditsia sinensis in Guizhou Province, China

In order to reveal the phenotypic variation degree and variation pattern of the natural population of Gleditsia sinensis in Guizhou Province, and lay a theoretical foundation for the genetic improvement, germplasm identification and variety breeding of G. sinensis. This study measured 12 phenotypic traits of seeds and pods in 180 individual trees from 17 natural G. sinensis populations in Guizhou Province and detected rich phenotypic diversity. The results suggest that the phenotypic variation of G. sinensis seeds and pods in Guizhou is extremely rich, with intrapopulation variation being the primary source of variation. The average phenotypic differentiation coefficient is 23.87 %, and the average coefficient of variation is 11.59 %. The variation in phenotypic traits of G. sinensis seeds and pods is geographically discontinuous. Generally, pods show north-south variation along the same longitude, while seeds exhibit east-west variation along the same latitude. Inter-population variability in pods (14.67 %) is higher than in seeds (8.96 %), suggesting greater variability in pod traits and higher stability in seed traits. This multi-level variation provides a scientific basis for the innovative utilization of high-quality genetic resources of G. sinensis. Principal component analysis shows that the first three principal components (size of pods, size and weight of seeds, weight of pods) account for 81.9 % of the cumulative contribution, essentially reflecting most of the information on phenotypic traits of G. sinensis. A comprehensive evaluation of the natural populations of G. sinensis based on 12 pods and seeds traits finds that the CeHeng (CH) population has the best overall performance, followed by WangMo (WM), DeJiang (DJ), and Weng'an (WA) populations. Suitable breeding materials can be selected from these four populations based on breeding objectives. This research findings lay a crucial foundation for advancing the genetic improvement of G. sinensis and provide a scientific underpinning for the development of breeding strategies and management practices.