Abstract:In this study, the effects of methyl jasmonate (MeJA) with various concentrations (0,0.5, 1.0, 5.0, 10.0, 25.0 μmol·L-1) on seed germination and seedling growth and antioxidant system of coreopsis has been explored. Seeds were germinated on filter paper bedding and leaf spray of potted seedlings. The results showed that the growth of coreopsis was severely inhibited when the cadmium ion concentration is 100 μmol·L-1. The application of MeJA (1.0-5.0 μmol·L-1) promoted the germination and increase the chlorophyll content of coreopsis seedlings, promoted leaf dry matter accumulation and increased relative leaf water content, increased the activities of antioxidase, increased the contents of oxidized glutathione and the rate of oxidized glutathione/reduced glutathione values, reduced the contents of malondialdehyde and proline. The low concentration of MeJA could effectively alleviate the damage of cadmium stress. However, high concentration of MeJA (above 10 μmol·L-1) exhibited inhibitory effects on the metabolism of coreopsis seedlings. Overall, appropriate concentration of exogenous MeJA could promote the growth and cadmium tolerance of coreopsis, through decreasing osmotic adjustment substance contents, enhancing antioxidant enzyme activities, increasing GSH content and adjusting GSH/GSSG ratio.