Abstract: The genetic diversity of 93 cultivars in D. grandiflorum was investigated using peroxidase isozyme ( POD) and esterase isozyme （EST）, and 12 loci were obtained. The genetic variation of cultivars in Dendranthema grandiflorum was very high, and the average of the effective number of alleles per locus (A), percentage of polymorphic loci (P) and heterozygosity (Ho) among all the cultivars were 1.5699、43.23%、0.5699. ‘Zigonglingguan’ was the highest, and A, P and Ho were 1.8889, 66.67％, and 0.8889, while ‘Fenziguan’ , ‘Fenguantuogui’ and ‘X16’ had the lowest genetic variation and A, P and Ho were 1.3000, 25.00％, 0.3000, respectively. The UPGMA of 89 cultivars in D. grandiflorum showed that they were clustered together. The big-headed chrysanthemum cultivars possessed the similar genetic characteristic , and so did the small-headed ones, and the ones with anemone petals clustered alone. 70.37% cultivars of the big-headed chrysanthemum which had the same A, P and Ho were clustered together, and so did 87.18% cultivars of the small-headed ones. The clutivals with anemone petal were clustered solely. ‘Ranshuijintao’, ‘Fenzhuqiuyi’, ‘Jinlingzhiguang’ and ‘Jinlingchunse’ had the specifical band (the band F of POD-3), which could offer the biology chemistry evidence for protecting the new cultivars in D. grandiflorum.

Key words: chrysanthemum cultivars , peroxidase isozyme ( POD), esterase isozyme（EST）, genetic diversity, variety protection