Objective The study aims to provide a solid theoretical basis and excellent germplasm materials for the breeding of superior varieties and comprehensive utilization of Elaeocarpus braceanus resources through the analysis and comprehensive evaluation of variation patterns of fruit traits of E. braceanus germplasm resources naturally distributed in Yunnan Province of southwestern China.

Method Taking 208 individual plants of E. braceanus from eight naturally distributed populations in Yunnan Province as materials, variation analysis, correlation analysis, and principal component analysis were carried out on 16 fruit traits. Superior germplasms were screened by combining the principal component evaluation method, fuzzy membership function evaluation method, multi-dimensional coordinate comprehensive evaluation method and gain analysis.

Result (1) The coefficient of variation of fruit traits in E. braceanus ranged from 2.66% to 84.18%. The coefficient of variation of gallic acid content was the highest (84.18%), followed by vitamin C content (67.72%), total phenol content (40.60%), soluble solid content (35.09%), total sugar content (34.03%), kernel mass (27.85%), and fruit mass (26.89%). The coefficient of variation of crude fiber content (12.17%), kernel longitudinal diameter (12.04%), fruit longitudinal diameter (11.59%), kernel transverse diameter (10.35%), fruit transverse diameter (9.44%), fruit shape index (7.59%), edible rate (6.85%), and water extract content (2.66%) were relatively small. (2) Fruit mass, fruit longitudinal diameter, and fruit transverse diameter were extremely significantly positively correlated with edible rate, and extremely significantly negatively correlated with gallic acid and total phenol content. Kernel mass was extremely significantly negatively correlated with edible rate and total phenol content. Soluble solid content was significantly positively correlated with total phenol, water extract and gallic acid content. Crude fiber content was extremely significantly positively correlated with gallic acid content. (3) Cluster analysis divided the germplasm resources of E. braceanus into three groups: group Ⅰ was the small-fruit type, group Ⅱ was the medium-fruit type, and group Ⅲ was the large-fruit type. (4) The 16 fruit trait indicators constituted five principal components, F₁ represented fruit size factor, F₂ represented the kernel size and medicinal component factor, F₃ represented fruit morphology and medicinal component factor, F₄ and F₅ both represented the fruit nutrition and medicinal component factors. The cumulative contribution rate reached 71.317%, covering most of the information on fruit traits of E. braceanus. (5) Through three evaluation methods, nine superior germplasms, namely XD11, NK13, LC28, SJ05, MB05, MB11, MB12, WQ04 and WQ20 were screened out, which all belong to group Ⅱ and group Ⅲ. These germplasms showed significant advantages in fruit size, morphology and related inclusion indicators.

Conclusion The medicinal and yield-related traits of E. braceanus, represented by gallic acid content, vitamin C content, total phenol content, and seed mass have a large degree of variation, providing abundant resources for breeding of superior varieties. The large fruit and medium fruit groups are more likely to produce superior germplasm individuals stably. 9 superior germplasms of E. hookerianus were selected, which can serve as important basic materials for selection of superior strains and rapid propagation, and they are recommended for application and promotion in actual production.