Abstract: In order to discover aphid-resistant germplasm, 32 cut chrysanthemum (Chrysanthemum grandiflorum) cultivars were artificially inoculated with aphids, and the aphid number and its ratio on the cultivars were investigated. Different chrysanthemum cultivars had different levels of aphid-resistance. After 21 days inoculation, the aphid number varied with cultivars, ranging from 0 to 267. The aphid-resistance of chrysanthemum could be divided into five grades in terms of aphid number ratio, i.e., high resistance (aphid number ratio 0-0.25), moderate resistance (0.26-0.50), resistance (0.51-0.75), low resistance (0.76-1.25), and non-resistance (>1,25). Among 32 test cultivars, 14 cultivars were of non-resistance, 4 cultivars were of low resistance, 3 cultivars were of resistance, 1 cultivar was of moderate resistance, and 10 cultivars were of high resistance.

Key words: Sorbus amabilis, Genetic diversity, RAPD