Studies on photosynthetic characteristics of medicinal plant Fagopyrum cymosum

Objective: To study the photosynthetic characteristics of leaves for improving the quantity and quality of Fagopyrum cymosum.Method: The light-response and diurnal photosynthesis course of leaves at the booting stages of F.cymosum species GuizhouⅠand JiangsuⅡ,were analyzed by LI-6400 system under natural condition.Result: The light-response curve of F.cymosum matched the non-rectangular hyperbola model,and the light saturation point(LSP) and light compensation point(LCP) of GuizhouⅠwere higher than those of JiangsuⅡ,which implied that F.cymosum of GuizhouⅠcould adapt to environment more widely.Diurnal course curves of the net photosynthetic rate,photosynthetically active radiation,stomatal conductance and transpiration rate all had a single peak,without obvious midday depression.The relativity analysis indicated that the net photosynthetic rate of F.cymosum had a positive correlation to the stomatal conductance,photosynthetically active radiation,transpiration rate and water utilization efficiency,and negative to the intercellular CO2 concentration.Conclusion: Stomatal conductance,photosynthetically active radiation and transpiration rate were the main environment factors that affected the net photosynthetic rate of F.cymosum.