[Effects of low-light stress on photosynthetic characteristics of Paris polyphylla var.  chinensis in artificial domestication cultivation]. 
To decide on the optimum artificial domestication cultivation light environment for Paris polyphylla var.  chinensis through investigating the effect of light intensity on leaf's gas exchange parameters, photosynthetic parameters, light saturation point and compensation point of Paris polyphylla var.  chinensis.  Different low-light stress gradients' effect on the growth of Paris polyphylla var.  chinensis was compared with no low-light stress treatment through calculating leaf's gas exchange parameters, photosynthetic parameters, light saturation point and compensation point, and then all these parameters were statistically analyzed.  Light intensity had significant influence on the photosynthetic characteristics of Paris polyphylla var.  chinensis.  With the strengthening of the low-light stress, chlorophyll content, gas exchange parameters, photosynthetic parameters P., AQY and light saturation point all gradually increased at first, and then decreased.  However, both photosynthetic parameters Rd and light compensation point firstly decreased and then rose again.  These results showed that too strong or too weak light intensity affected the optimization of photosynthetic parameters of Paris polyphylla var.  chinensis.  The optimal illuminance for each parameter was not completely same, but they could all reach a relative ideal state when the shading ranges between 40% and 60%.  However, photosynthetic parameters deteriorated rapidly when the shading surpass 80%.  For artificially cultivating Paris polyphylla var.  chinensis in Baoxing,Sichuan or the similar ecological region, shading 40%-60% is the optimal light environment, which can enhance the photosynthesis of Paris polyphylla var.  chinensis and promote the accumulation of photosynthetic products.