摘要：In the lower reaches of Tarim River, based on the habitat characteristics and salt-tolerant characteristics of p. euphratica, different concentrations of NaCl solution (0 mM; 50 mM; 150Mm; 300 mM) were used to irrigate on seedlings of P. euphratica. Na~+, K~+, Cl~- concentration in different parts of the P. euphratica seedlings were measured. Meanwhile, chlorophyll (Chl-a; Chl-b), Proline (Pro) content in leaves of the P. euphratica seedlings also were measured, and water potential of the leaves (ψ), stomatal conductance (g_s), stem xylem hydraulic conductivity and sap flow flux (F_s) were monitored in situ. The aim was to explore biochemical and physiological effects of seedlings of P. euphratica under salinity stress. Experimental results showed that with the increasing concentration of NaCl solution for irrigation, P. euphratica seedlings under osmotic stress. In various parts of the seedlings Na~+, Cl~- with K~+ contents had significantly negative correlation relationships respectively (sig.<0.05). Na~+ and Cl~- concentrations increased to inhibit the absorption and transport of K~+, this effects mainly reflects in K~+ concentration significantly reduced (sig.<0.05) in the leaves. Ions content ratios change showed that ion balance was disturbed, especially in the roots and leaves. This relationship was more noticeable in higher concentration NaCl solution treatment (150 mM and 300 mM). The chlorophyll content was increased under salt stress of NaCl solution at lower concentration (50 mM), but Chl-a / Chl-b value decreased, and no significant changes in other salt irrigation treatment. pro in Populus seedlings accumulated more significantly at a higher level of salinity (150mM and 300mM). Leaf water potential monitoring results showed, NaCl solution irrigation decreased the predawn water potential with the extension of stress time, and decreased the leaf water potential with the increase of NaCl concentration. Under salt water irrigation, the peak time of stomatal conductance was advanced. Under severe salt stress 300 mM, hydraulic conductivity safety and efficacy of water transportation of stem xylem in P. euphratica seedlings significantly decreased. Stem sap flow flux decrease significant (p<0.05). Comprehensive analysis think that the physiological and biochemical parameters of P. euphratica seedlings can be used for determining the index of salt tolerance, Seedlings of P. euphratica can maintain normal growth when irrigation with the concentration of 50 mM NaCl solution, under stress when with 150 mM NaCl solution, salt water irrigation in 300 mM subjected to severe stress, equivalent drought stress.
