Extensive degradation of irrigated croplands, due to increasing salinity and depletion of soil nutrient stocks,is a major problem in arid areas of northwest in china.Elaeagnus angustifolia is one of the most important woody species in these areas.To determined the response of Elaeagnus angustifolia to salinity in terms of photosynthetic gas exchange、chlorophyll a fluorescence and pigment contents of one years old seedlings exposed to one week of various salt levels(0,200,400,600mM).

Salinity stress caused significant reduction in net photosynthetic rate (PN), transpiration rate(E),and stomatal conductance(gs),as well as electron transport rate(ETR).The maximal efficiency of PSII (Fv/Fm)and photochemical quenching coefficient (qp) showed no significant changes with increasing NaCI concentration. A strongly linear correlation was observed between chlorophyll (Chl) a/b content and photosynthetic gas exchange. The results indicate that the severe reduction in stomatal conductance and transpiration rate represent an adaptive mechanism to cope with excessive salt, rather than merely being a negative consequence of it. These can, therefore, conclude that Elaeagnus angustifolia at their threshold salinity tolerance reveal a combination of low(but positive)PN and minimum E,by regulating gs, and coupled with photoinhibition.