Abstract: [Objective] This study aimed to disclose the genetic variation, compare and evaluate the diversity in contents of 8 main active components in Eucommia ulmoides male flowers, to provide a scientific basis and materials for resources selection and utilization of the male flower.[Method] A total of 193 E. ulmoides germplasms were selected as samples, the content of total flavonoids and amino acids were determined by the AlCl₃ colorimetric method and an automatic amino acids analyzer, respectively. Aucubin, geniposidic acid, chlorogenic acid, geniposide, isoquercitrin and astragaline were determined by HPLC method. Furthermore, variation analysis, multiple comparison, correlation analysis, principal component analysis and cluster analysis were carried out based on 8 active components contents.[Result] In different E. ulmoides germplasms, the content and diversity index of amino acids were highest among the 8 components, with an average of 206.23 mg·g^-1 and 2.05, respectively. The variation coefficient of geniposide content was highest (112.00%) and of amino acids content was lowest (12.52%). Correlation analysis showed that aucubin, geniposidic acid, chlorogenic acid, geniposide and isoquercitrin were extremely significantly and positively correlated with each other. The correlation between amino acids and total flavonoids was extremely significant and positive, while amino acids were not significantly correlated with the other 6 components. Principal component analysis revealed that the first four principal components represented 87.040% of 8 active components, and they were suitable for assessing the E. ulmoides male flower resources. Based on data of 8 active components, 193 E. ulmoides germplasms were clustered into 5 groups and the contents of 8 active components were significantly different among the 5 groups. The contents of 8 active components were comparatively lower in the first group, the amino acids content in the second group was higher than the other 4 groups, the content of total flavonoids and flavonoids components were highest in the third group, the content of iridoid components were highest in the fourth group, and chlorogenic acid and geniposidic acid content in the fifth group were higher than the other 4 groups. Different types of E. ulmoides male flowers were preliminarily defined.[Conclusion] The contents of 8 main active components in E. ulmoides male flowers were high with great value of utilization, and high diversity and variation were found in different germplasms, which showed great potential for selection and imporvement. Thus, it could provide basal materials for the male flower breeding and the resources development and utilization.

Key words: Eucommia ulmoides, male flowers, germplasms, active components, diversity