[Objective] This study aimed to explore the effects of treatments with three types of exogenous oxidase solutions and H2O2.solution on the somatic embryogenesis of Fraxinus mandshurica Rupr. （Oleaceae）. [Method] The immature zygotic cotyledons were treated with PPQ （polyphenol oxidase） solution, GQD （glucose oxidase） solution, SOD （superoxide dismutase） solution and H202 （hydrogen peroxide） at different concentrations to explore the effects on the growth, browning and somatic embryogenesis on cotyledon explants in the somatic embryogenesis of F. mandshurica. Through comparative analysis on the effects of different treatments on somatic embryogenesis of F. mandshurica, the relationship between explants browning and somatic embryogenesis was uncovered during the somatic embryogenesis of F. mandshurica. [Result] H2O2 treatment not only advanced the explants browning, but also inhibited the growth and somatic embryogenesis of explants; different concentrations of PPQ promoted the growth and browning of explants, as well as improving the incidence of somatic embryogenesis; both GOD and SOD treatment could raise the explants browning rate; when somatic embryogenesis of explants treated with enzyme solutions advanced, the incidence of somatic embryogenesis was low; however, when the disparity of the incidence of somatic embryogenesis between 30 and 60 d treatments reached its peak, the incidence of somatic embryogenesis was also high. [Conclusion] The results of this study provide basis for raising the incidence and improving the status of somatic embryogenesis of F. mandshurica, as well as optimizing the somatic embryogenesis system of F. mandshurica.
