Abstract: This paper investigated the photosynthetic fluorescence properties and aboveground biomass of currentyear Medicago sativa (Golden Empress) in response to enhanced UVB radiation by 5% (T₁) and 10% (T₂) under severe cutting. The results indicated that, with the increase of UV-B radiation, all the experimental indicators declined significantly compared with those of CK in each growth stage. After cutting, the contents of Chla, Chlb and Chl(a+b), net photosynthetic rate and fluorescence parameter F_v/F_m of M. sativa increased significantly at the low dose of UV-B radiation (T₁) in the branching stage and podding stage. At the high dose of UV-B radiation (T₂), cutting significantly enhanced those five indicators by 32%, 30%, 20%, 17% and 22% respectively in the branching period and podding period. The aboveground biomass after severe cutting increased by 49% and 199% after T₁ and T₂ treatments, respectively. The cutting and the enhanced UV-B radiation did not show significant interaction on photosynthesis and fluorescence of M. sativa. So it was concluded that moderate cutting can alleviate the damage of UV-B radiation on M. sativa to a certain extent.

Key words: Taihu Area, return of green manure to soil,  topdressing of , inorganic nitrogen fertilizer, no basal dressing.