Study On The Resources Diversity Of Chrysanthemum Cultivars In Kaifeng City

Chrysanthemums (Dendranthema grandiflora) are a genus of herbaceous perennial flowering plants. Indigenous to China, Chrysanthemum species are among the most important ornamental plants worldwide. They also possess significant culinary and medicinal values. The City of Kaifeng and its surrounding region is arguably the center of Chrysanthemum cultivation in China. Chrysanthemum germplasm resources of this region however have not been systematically categorized, let alone effectively managed. Although many Chrysanthemum classification systems exist, none is accepted universally. Newer classification methods utilizing molecular techniques can complement the traditional morphological approach; it is however very difficult to acquire specificity and polymorphism markers. The repeatability of molecular techniques also needs to be improved. Research progresses have been made concerning the phylogeny and genetic diversity of Chrysanthemum cultivars. Nonetheless, a coherent picture of Chrysanthemum cultivar diversity is yet to emerge. Such a picture will significantly facilitate future researches on the morphology, origin, evolution, classification and phylogeny of Chrysanthemum.In this study, the diversity and phylogeny of Chrysanthemum cultivars in the Kaifeng region were investigated using statistical, morphological and biometric methods. The results are as follows:(1) 820 Chrysanthemum cultivars were identified, including 788 Exhibition mums and 32 Garden Hardy cultivars. The Exhibition cultivars had 5 floret types, 33 bloom forms and 7 colors. The Garden Hardies had 4 floret types, 8 bloom types and 5 colors. Extremely rich in color, these cultivars spanned almost the entire morphological spectrum described in Li Hongjian's classification system.(2) The Yuwangtai Park preserved more Chrysanthemum germplasm resources than the Chrysanthemum Research Center. These two hotspots of Chrysanthemum germplasm resources did not have a common classification standard.(3) Fifteen cultivars were studied in the Henan University. 65 characters were analyzed for consistency, stability and variability. The results showed that flower and leaf characters were more consistent than the other characters, and could be used for morphological classification of Chrysanthemums.(4) Cluster analyses were performed on 15 cultivars from the Henan University and 50 cultivars from the Yuwangtai Park. The results showed that flower diameter, inflorescence type and plant type could be used for primary classification.(5) Chrysanthemum cultivars in the Kaifeng region showed very high levels of genetic diversity, suggesting frequent cultivar exchanges with other Chrysanthemum cultivation centers.(6) Both morphological and biometric characters could be used for classifying Chrysanthemums. Combining these with molecular techniques would improve the reliability and accuracy of Chrysanthemum classification.