Research on the Response of the Photosynthesis,Transpiration and Fluorescence Index of Ulmus pumila L.and Ulmus pumila cv.jinye to Water Stress

[Objective] The difference in the drought tolerance between Ulmus pumila L.and Ulmus pumila cv.jinye was analyzed.[Method] The potted experiment in the drought tolerance of the seedlings of 2 year-old Ulmus pumila L.and Ulmus pumila cv.jinye that were planted in soil with 4 gradient levels of moisture and the photosynthesis,transpiration and fluorescence parameter of the seedlings were measured with GFS-3000 portable photosynthesis measurement system.[Results] With the intensification of water stress,the photosynthetic rate,transpiration rate,water-using efficiency,stomatal conductance of Ulmus pumila L.and Ulmus pumila cv.jinye showed a downward trend and the higher the degree of water stress was,the smaller the declining degree of Ulmus pumila cv.jinye photosynthetic rate was than that of Ulmus pumila L.Under the condition of severe water stress,the transpiration rate and non-photochemical quenching of Ulmus pumila cv.jinye was significantly lower than these of Ulmus pumila L.and the stomatal conductance,chlorophyll fluorescence parameter and non-photochemical quenching of Ulmus pumila cv.jinye were significantly higher these of Ulmus pumila L.[Conclusion] In dry conditions,the ability of Ulmus pumila cv.jinye in drought resistance,self-regulation and adaptable to environment was stronger than these of Ulmus pumila L.and Ulmus pumila cv.jinye was with even greater potential in severe drought environment.