Abstract: This paper analyzed the differences of morphological indexes, physiological indexes and metabolism indexes caused by the seedlings gender in condition of overshadow, and discussed the strategies response to overshadow, provided theoretical basis for the protection of wild resources and forestation of the seedlings. The differences of morphological characteristics, biomass distribution, antioxidative enzyme activity and metabolism of the biennial Phellodendron amurense seedlings were studied by using the control experiment with three shading gradients and sun light as the control. The results showed that overshadow was more beneficial to the growth of P.amurense, the biomass accumulation of female plants in light shading were better than male plants, but in severe overshadow male plants were better than female plants, overshadow had a significant effects on chlorophyll a and the total chlorophyll content(P<0.01), and there was no significant effect on gender, and shading treatment was promotive to the chlorophyll accumulation of P.amurense seedlings; shading treatment had a significant effect on enzyme activity and MDA content, however, activities of POD and CAT were decreased with the shade intensity increased, MDA content was the highest in the control treatment, soluble sugar and starch content decreased under shading condition, but there was no significant effect on gender. The seedlings of P.amurense adapted to the shade by changing the component properties, biomass, antioxidant enzyme activity and metabolic substance content. The gender differences of the effects of shading on the growth and physiology of P.amurense would lay a foundation for the individual development, population formation, adaptation mechanism and population reproduction of P.amurense under shading environment, and would provide scientific reference for the protection and utilization of dioecious plant resources.

Key words: Phellodendron amurense Rupr., shading, morphology, physiology, gender