Abstract: Lycium barbarum is an important traditional medicinal plant in China. Under controlled condition, a field experiment was conducted to study the effects of different monthly irrigation quota on the leaf structure, photosynthetic physiology, and fruit yield of L. barbarum, aimed to determine an appropriate irrigation amount for the plant. When the monthly irrigation quota was less than 900 m³·hm^-2, the leaf area, leaf thickness, palisade tissue thickness, cell tense ratio (CTR), net photosynthetic rate (P_n), intrinsic water use efficiency (WUE), stomatal limitation value (L_s), and fruit yield of L. barbarum all increased significantly with monthly irrigation quota, while leaf stoma density and intercellular CO₂ concentration (C_i) showed a reverse trend. When the irrigation quota was more than 900 m³·hm^-2, the C_i increased with irrigation quota, the leaf area, stoma density, and fruit yield had no obvious change, whereas the other indices showed a reverse trend. The leaf transpiration rate and G_s were the highest at irrigation quota 450 m³·hm^-2, being 8.02 and 324 mmol·m^-2·s^-1, respectively; whereas at other irrigation quota, these two indices were lower than the control. In terms of saving water, the monthly irrigation quota 900 m³·hm^-2was more appropriate for Lycium barbarum.

Key words: irrigation amount, Lycium barbarum, leaf structure, photosynthetic physiology, fruit yield