Genetic diversity and comprehensive evaluation of chrysanthemum germplasm resources

【Objective】 The genetic diversity of agronomic traits of different chrysanthemum germplasm resources formedicinal purposes was analyzed and their quality indexes were comprehensively evaluated, which provided theoreticalbasis for the adaptability study of chrysanthemum germplasm resources for medicinal purposes in Shandong and the bree-ding of chrysanthemum varieties for medicinal purposes. 【Method】The 27 main agronomic traits of 20 chrysanthemumgermplasm resources for medicinal purposes were analyzed, and the contents of 3 main medicinal active components（ pri-mary acid, luteolin, 3,5-O-dicaffeoyl quinic acid） were determined. The genetic diversity analysis, principal componentanalysis（PCA） and cluster analysis were performed. 【Result】 The Shannon-Weaver index（H′） of 20 chrysanthemum germplasm resources for medicinal purposes was 0.28-3.11. The coefficient of variation ranged from 11.18% to 114.20%, and the H’ of the secondary branch was the highest（ 3.11）. The coefficient of variation of the number of flower head per plant was the highest（ 114.2%）. The contents of 3,5-O-dicaffeoyl quinic acid and chlorogenic acid in Bo chrysanthemum were the highest at 5.230% and 1.070% respectively. In contrast, Huangshan Tribute chrysanthemum exhibited the lowest levels of these active ingredients, with respective values of 0.240% and 0.110%. Additionally, the luteolin content was found to be the highest in Guifei chrysanthemum at 1.886%. However, the luteolin content in Huangshan Tribute chrysan-themum and Jiaxiang wild chrysanthemum was notably lower, at 0.082% and 0.095% respectively. The results of PCA analysis showed that the cumulative variance contribution rate of the first 4 principal components reached 84.825%. According to the main determining traits of the first 4 main components, they were named yield factor, shape factor, quality factor and plant factor, and the top 5 germplasm resources in comprehensive evaluation were Golden Silk chrysan-themum, Chuzhou chrysanthemum, Wuyuan chrysanthemum, Daban chrysanthemum and Guifei chrysanthemum. The 20 chrysanthemum germplasm resources were divided into 4 germplasm groups by Q-type cluster analysis. TheⅠgroup was Golden Silk chrysanthemum, which had good commercial property; the flowers of the Ⅱ group were mainly white flowers with high medicinal value, and the Ⅲ group was mainly yellow tube flowers with high yield; the Ⅳ group was Jiaxiang wild chrysanthemum, which had good stress resistance. Based on the results of R-type correlation cluster analysis, 27 agronomic traits and 3 main medicinal active ingredients contents indexes of different chrysanthemum germplasm resources for medicinal purposes could be divided into 4 categories. The number of flower head per plant was extremely significantly and positively correlated with branch density（ P＜0.001） and crown width（ P＜0.01）, and was significantly and positively correlated with secondary branches（P＜0.05, the same below）, chlorogenic acid content was extremely significantly and positively correlated with 3,5-O-dicafeoyl quinic acid content（ P＜0.01）, and was extremely significantly and negatively correlated with growth habit（ P＜0.01）. Luteoside content was significantly and positively correlated with inflorescence diameter, plant height and Terminal lobe length of leaf, and significantly and negatively correlated with flower center type.【 Conclusion】The 20 chrysanthemum germplasm resources for medicinal purposes have high diversity index, and rich genetic diversity, large variation coefficient, and high variation degree of chrysanthemum germplasm resources. In actual practice, parent materials can be selected according to different breeding targets.