The combined effects of drought and low light on biomass partition, foliar nitrogen concentration, membrane stability and active oxygen species (AOS) and antioxidant system were investigated in dragon spruce(Picea asperata Mast.) seedlings grown at two watering regimes (well-watered, 100% of field capacity and drought,30% of field capacity) and light availabilities (HL, 100% of full sunlight and low light, 15% of full sunlight). Under high light condition drought not only reduced foliar nitrogen
concentration (Nmass) and membrane stability index (MSI) but also significantly increased biomass partitioning to roots, AOS, ascorbic acid (AsA) content and antioxidant enzyme activities including superoxide dismutase (SOD,EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), catalase(CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase(GR, EC 1.6.4.2).However, no prominently drought-induced differences in biomass partitioning to root, SOD, GR activities, hydrogen
peroxide (H2O2) and MSI were observed in low light seedlings. On the other hand, significant interaction of drought and low light was found on MSI, the antioxidan enzymes activities (SOD, POD, CAT, APX, GR), H2O2 and superoxide radical (O2-). These results suggested that seedlings grown at the understory were more sensitive to drought than low light.