Effects of shade treatment on growth and photosynthesis characteristics of Sorbus folgneri seedlings

Morphological,biomass accumulation and allocation,physiological responses and leaf anatomical structure of 1-year-old Sorbus folgneri seedlings were examined with 4shade levels(0%,67%,76%and 92%).The results showed that the shade treatments produced plants with less height and main root length,greater stem diameter and leaf area.Shading screens of 67%increased but 76% and 92% decreased biomass accumulation.Shading treatments caused root and stem mass ratio,and higher leaf mass ratio,higher specific leaf area and shoot to root ratio were beneficial to the increase of light energy capture.With the increase of shading rate,thickness of bladereduced,skin cells thickness,the 2layer of palisade parenchyma reduced to 1layer,palisade/spongy ratio decreased and showed a tendency of palisade tissue turning into spongytissue.Concentration of chlorophyll increased,Chla/b decreased without obvious difference and the value about 2.3.The curve of diurnal variation of net photosynthetic rate and transpiration rate had one peat in a day,without midday depreesion phenomenon,and daily mean all got lower with the increase of shading rate.The results indicated that S.folgneri had the ability to adjust to shading,a moderate amount of shade was favorable to the growth and development.