Abstract: Based on a 6-year simulation N deposition experiment, we investigated the effects of N deposition on the litter quality in a temperate grassland. Mixed and monospecific litter from four N treatments, including control (0 g N·m^-2·a^-1), low nitrogen (5 g N·m^-2·a^-1), medium nitrogen (10 g N·m^-2·a^-1), and high nitrogen (15 g N·m^-2·a^-1) were collected. The basic properties of litter quality (concentrations of cellulose, hemicellulos, lignin, C, N and P) were measured. The results indicated that N deposition decreased the concentration of cellulose, hemicellulos and lignin in litter, while increased the N and P concentration. The effect of N deposition on the concentration of C was not significant. The ratios of C/N and C/P were decreased by N deposition. Our results suggest that the litter decomposition rate may be stimulated by simulated N deposition due to the increase of N and P concentration and decrease of structural carbohydrate and lignin in plant litter.

Key words: high temperature, over expression, PSⅡ activity, photosynthetic rate, cucumber., CsRCA