Abstract:Twelve species of shade plant were used to study the photosynthetic characteristics under sun-shading conditions.The net photosynthetic rate change,average net photosynthetic rate,apparent quantum yield and light compensation point was investigated under different sunshading conditions.The results showed that the photosynthetic characteristics changed under different shading treatments.When the sun light was weak,the net photosynthetic rate varied from a two-peak curve to a single-peak one,which only happened under a certain sun-shading degree.With the increase of sun-shading degree,the daily average net photosynthetic rate and the apparent quantum yield increased to a peak,and then fell down while the light compensation point decreased continuously.There were extremely significant differences for each index of photosynthetic characteristics among 12 species of shade plant under different sun-shading treatments.Proper sun-shading is beneficial to the growth of shade plant and improvement of photosynthetic characteristics.