Effects of soil water stress on photosynthetic characteristics ofMisconstrues sacchariflorus

Effects of different soil water stress degrees on physiological characteristics of Misconstrues sacchariflorus were studied by four treatments: CK (keep the maximum capacity of 80%, the same below), light water stress (65%), moderate water stress (45%), and severe water stress (30%). Results showed that the leaf relative water content (RWC), specific leaf weight (SLW) and chlorophyll (Chl) content, maximum net photosynthetic rate (Pmax), apparent quantum efficiency (AQE), dark respiration rate (Rd), transpiration rate (Tr), intercellular CO2 concentration (Ci), stomatal conductance (Gs), light saturation point (LSP) and light compensation point (LCP) decreased with the increasing of the degree of water stress (P＜0.05). However, stomatal limitation (Ls) showed a rising trend(P＜0.05), while water use efficiency (WUE) increased firstly and then decreased(P＜0.05). Leaf gas exchange parameters and physiological indicators of M.sacchariflorus showed poor adaptive capacity to water stress with low plasticity.