Effects of shading on seedling growth and photosynthetic characteristics of Taxus cuspidata

Under four kinds of conditions(100%,70%,40% and 10%),the seedling growth and photosynthetic characteristics of Taxus cuspidata was studied,the results show that: under 100%,70% light,the net photosynthetic rate(Pn) showed the day changes in bimodal curve,with a clear light lunch break phenomenon,light lunch break role of the latter than the former weakened 17.7 percentage points;The main environmental factors which caused the phenomenon were strong light,high temperature and low humidity.Under 70%full sun,the biomass of basal diameter and seedling height was the biggest among four shading levels,respectively.The Pn and WUE was the biggest at 70%full sun respectively.Therefore,Taxus cuspidate grows better in 70% intensity than the others.