[Objective] This study aimed to investigate the effects of different exoge- nous hormones on the rooting of Syringa microphylla cuttings and the change in related enzymes activity during the rooting process. [Method] Three different exoge- nous hormones IBA, NAA and ABT, each with concentrations of 500, 1 000, 1 500 and 2 000 mg/L were used to treat S. microphylla cuttings, and changes in the ac- tivities of peroxidase （POD）, poiyphenol oxidase （PPO） and indoleacetic acid oxidase （IAAO） during the rooting process were also investigated. [Result] The most appro- priate concentrations of IBA, ABT and NAA were 1 500, 1 000 and 1 000 mg/L, respectively, and the 1 500 mg/L IBA treatment exhibited the best effect on rooting. Throughout the rooting process, POD and PPO activities showed the same trends in the treatment groups as those in the control group, but the POD and PPO activi- ties in the treatment groups were increased significantly, with greater amplitude of variation; at the early stage, IAAO activity exhibited an opposite trend between the control group and the treatment groups, which increased slowly in the former, but decreased rapidly in the latter, and it was significantly lower in the treatment groups compared to the control; additionally, higher POD and IAAO activities were con- ducive to the induction of adventitious roots, and lower POD and IAAO activities fa- vored their formation and elongation. [Conclusion] This study has preliminarily clari- fied the rooting mechanism of S. microphylla cuttings.
