Abstract: Ground2cover chrysanthemum (Dend ranthem a m orifolium‘Beiguozhichun’) was used to understand the effects of nitric oxide (NO) and hydrogen peroxide (H₂O₂ ) on rooting of p lant cuttings and the changes of activities of superoxide dismutase ( SOD) , peroxidase (POD) and polyphenol oxidase ( PPO) and the total polyphenol content of cutting leaves. The results showed that the effects of exogenous H₂O₂ or NO on rooting of ground-cover chrysanthemum cuttings was dose dependent, with a maximal biological response at 200μmol·L ^-1H₂O₂ or 50μmol·L ^-1 NO donors SNP. At the same time, the rooting percentage of cuttings treated with both SNP and H₂O₂ was significantly higher than that of cuttings treated with SNP or H₂O₂ alone,
which suggested that there might exist synergistic action between H₂O₂ and NO on mediating rooting. Additionally, compared with the control, SNP, H₂O₂ and SNP +H₂O₂ treatmentsmight significantly increase the activities of SOD and PPO of ground-cover chrysanthemum cuttings leaves. However, the activities of PODand the total polyphenol content were significantly higher in control than in other treatments during rooting. Moreover, lower POD activities and polyphenol contentwere attained in SNP +H₂O₂ treatment than in SNP or
H₂O₂ treatment alone. Together, these results indicated that 50μmol·L ^-1 SNP and 200μmol·L - 1 H₂O₂ treatments enhanced rooting and root growth synergistically and independently by stimulating the activities of SOD and PPO enzymes, and simultaneously by rep ressing POD activities and the p roduction of polyphenol.

Key words: ground-cover chrysanthemum, nitric oxide (NO), hydrogen peroxide (H₂O₂ ), cuttings, rooting