Recently, Goji berry (Lycium barbarum L.) has been extensively cultivated to improve the fragile ecological environment and increase the income of residents in Qinghai Province, northwestern China. However, few studies have focused on the physiological responses of Goji berry under salt stress and alkali stress. Gas exchange, photosynthetic pigments, and chlorophyll fluorescence were evaluated in response to neutral (NaCl) and alkali (NaHCO) salt stresses. Nine irrigation treatments were applied over 30 days and included 0(Control group), 50, 100, 200, and 300 mM NaCl and NaHCO. The results showed that salt and alkali stress reduced all the indicators and that alkali stress was more harmful to Goji berry than salt stress under the same solution concentrations. The salt tolerance and alkali resistance thresholds were identified when the index value exceeded the 50% standard of the control group, and threshold values of 246.3 ± 2.9 mM and 108.4.7 ± 2.1 mM, respectively, were determined by regression analysis. These results were used to identify the optimal water content for Goji berry. The minimum soil water content to cultivate Goji berry should be 16.22% and 23.37% under mild and moderate salt stress soils, respectively, and 29.10% and 42.68% under mild and moderate alkali stress soil, respectively.
