Abstract: Photosynthetic characteristics of 3-years-old Korean spruce and Nenjiang spruce seedlings were studied under different water conditions in order to explore their adaptation mechanism to water stress. The results showed that maximum photosynthetic rate（P_max）under different light reduced with the reducing of soil moisture content, and the reduction of Nenjiang spruce is smaller; apparent quantum yield (AQY),transpiration rate(Tr), stomatal conductance (G_s) also decreased. Dark respiration rate（R_d）and water use efficiency（WUE） rised firstly and then descended as drought become intensified, however, intercellular (C_i)descended firstly then rised. These results showed that photosynthesis was limited by non-stomatal factor under serious drought. It is indicated that the ability to water stress of Nenjiang spruce is stronger than that of Korean spruce by comparing above indexes.

Key words: Picea koraiensis Nakai, Picea koraiensis Nakai var. nenjiangensis S.Q.Nie et X.Y.Yuan, water stress, photosynthetic characteristics