Effects of salt stress on plant growth,biomass accumulation and photosynthetic physiology of Shatangju saplings

【Objective】To investigate the adaptability of Shatangju sapling to salt stress,so as to provide scientific support for the introduction and cultivation of Shatangju and orchard soil management.【Method】CaCO₃,Na HCO₃and NaCl were used to simulate the main stress components of calcareous soil,alkaline soil and saline soil respectively,and the content levels of 0.3%and 0.7%were set.With no salt in the substrate as the control,the effects of salt and alkali types and contents on plant growth and biomass allocation and their basic physiological responses were tested and analyzed 90 days after cultivation.【Result】For Shatangju saplings under salt stress,the amount of fallen leaves per plant was1.85 to 17.66 times larger than that of the control.The amount of fallen leaves under NaCl stress was significantly greater than that under CaCO₃ or NaHCO₃ stress(P<0.05,the same as below).The inhibition of salt stress on plant height growth was significantly greater than that on ground diameter and crown width growth,and the effect on plant biomass accumulation was the greatest on leaf biomass,followed by the inhibition on root biomass accumulation.The root and leaf biomass of each plant under the two treatment intensities of NaHCO₃ and NaCl stress were significantly reduced compared with the control,Different types and levels of salt stress could reduce the chlorophyll content of Shatangju leaves,but the effects of 0.7%CaCO₃ stress and 0.3%NaHCO₃ stress,0.7%NaHCO₃ stress and 0.3%NaCl stress were similar.The photosynthetic rate,transpiration rate and stomatal conductance of Shatangju leaves were sensitive to salt stress,and the higher the salt content,the greater the decrease of three photosynthetic physiological indexes.There were significant differences in leaf water saturation deficits between the same nature and two levels of stress.When the salt content reached 0.3%,the MDA content in leaves increased significantly and the membrane permeability of cytoplasm increased significantly.【Conclusion】Shatangju leaves has strong adaptability to soil with high CaCO₃ content,but poor adaptability to saline soil dominated by NaCl and alkaline soil dominated by NaHCO₃.The damage to chlorophyll,the inhibition of photosynthetic physiology,and the accompanying water deficit and membrane lipid peroxidation in Shatangju leaves are the common characteristics of different types of salt stress.