Photosynthesis Characters of Tree Peony in Response to Soil Water Content

With potted Paeonia suffmticosa Andr.cv. Zhushalei as material,the effect of soil water on the photosynthesis characters of paeoy leaves under five drought stress developing. The results showed that with the soil water stress increasing,the photosynthetic rate(Pn),transpiration rate (Tr) ,stomatal conductance(Gs)declined,the apparent quantum yield(AQY) , carboxylation efficiency (CE) and the light saturation point(LSP) reduced ; The light compensation point(LCP) and CO2 compensation point(CCP) enhanced. When the relative soil water content were 55% -40%, the main reasons of the photosynthetic rate declined were stomatic limitation . When the relative soil water content were 20 % , the main reasons of the photosynthetic rate declined were nonstomatic limitation. The optimum SRWC of Pn was 70%.