Research Of Physiological Characteristics In Salix Fragilis L. And Populus Deltoids Cv.Zhonghua Hongye Under NaCl Stress

In order to explore salt tolerance mechanism of Salix fragilis L. and Populus deltoids cv.Zhonghua hongye with 2 years old wood seedlings by adding different concentration of Na Cl(respectively CK, 0.15%, 0.3%, 0.45%, 0.6%) to simulate the natural environment of salt stress environment, a series of physiological and biochemical parameters including plant growth, pigment content, light parameters(Pn, Gs, Ci, WUE),chlorophyll fluorescence parameters(Fv/Fo, Fv /Fm), superoxide dismutase(SOD) activity,peroxidase(POD) activity, malondialdehyde(MDA), soluble sugar content, soluble protein content, cell membrane permeability of Salix fragilis L. and Populus deltoids cv.Zhonghua hongye were studied under Na Cl stress. The results provide a theoretical basis for breeding salt-tolerant garden varieties.The conclusions were as follows:1.Under Na Cl stress, absolute height growth, absolute growth to stem volume and growth conditions of Salicaceae sp declined with the increasing concentration of Na Cl.When the Na Cl concentration is more than 0.45%, it caused great harm to the Salicaceae sp; The absolute height growth, absolute growth to stem and growth conditions of Populus deltoids cv.Zhonghua hongye increased first and then decreased with the Na Cl concentration increasing.It showed that the normal growth and metabolism was not affected by low concentration of Na Cl(Na Cl concentration ≤0.3%). In addition, Populus deltoids cv.Zhonghua hongye could still maintain growth under 0.6% Na Cl stress, but Salix fragilis L. appeared fall leaves, stem rot phenomenon of death.2.Under the Na Cl stress,pigment content of Salicaceae sp and Populus deltoids cv.Zhonghua hongye decreased, while chlorophyll content of Salicaceae sp was significant lower than that of control at 0.6% Na Cl concentration.3. The net photosynthesis, stomatal conductance, intercellular CO2 concentration, and water use efficiency of Salix fragilis L. and Populus deltoids cv.Zhonghua hongye changed obviously in different concentrations of Na Cl stress. Pn, Gs, Ci of two plants showed significant decreasing trend as Na Cl concentration and treatment time increasing.While water use efficiency of two plants showed a gradual increasing trend with the increasing concentration of Na Cl; Pn of Populus deltoids cv.Zhonghua hongye remained increasing trend in 0.3% Na Cl concentration.4. Fv/Fo and Fv/Fm ofn Salix fragilis L. could remain relatively stable in 0.15% Na Clstress within 7d, but they showed a significant downward trend when the Na Cl concentration were greater than 0.15% after 7d. Populus deltoids cv.Zhonghua hongye could remain relatively stable effective photochemical efficiency and primary photochemical conversion efficiency in order to ensure the normal physiological metabolism of plants in adverse environments at a low concentration of salt stress(less than 0.3%).5.Under the Na Cl stress,SOD and POD activity of Salicaceae sp and Populus deltoids cv.Zhonghua hongye Both first increased and then decreased, They reached peak at 0.45%and 0.3% Na Cl respectively. Soluble sugar content increased gradually and soluble protein content increased first then then decreased.6. MDA content and cell membrane permeability of Salix fragilis L. and Populus deltoids cv.Zhonghua hongye increased gradually with prolonging stress level and the processing time under Na Cl stress.7. The comprehensive results indicated that Populus deltoids cv.Zhonghua hongye had greater salt tolerance than Salix fragilis L.