The differences between two cultivars of Lycium barbarum in osmotic stress tolerance and salt tolerance

Growth, leaf tissue water content, Na+, K+ accumulation in plant tissues were studied under -0.5 MPa osmotic stress, 50 mmol·L-1 NaCl and salt-osmotic intercross stress in Bianguo and Ningqi0702, two cultivars of Lycium barbarum. The results showed that both the growth of Bianguo and Ningqi0702 was inhibited under -0.5 MPa osmotic stress. Compared with the control, fresh weigh (FW) and root height of Bianguo and Ningqi0702 decreased by 34%, 38%, 32% and 17%, respectively. The addition of 50 mmol·L-1 NaCl significantly increased FW of Bianguo by 38%, and no effect on dry weight (DW), plant height and root height of Bianguo. However, FW, DW, plant height and root height of Ningqi0702 significantly decreased by 27%, 34%, 44% and 14% under 50 mmol·L-1 NaCl conditions, respectively. The growth of Bianguo remained unaffected when plants were exposed to salt-osmotic intercross stress, whereas FW, DW, plant height and root height of Ningqi0702 significantly decreased by 37%, 28%, 44% and 13% under salt-osmotic intercross stress, respectively. Compared with the control, leaf tissue water content of Bianguo remained unaffected under osmotic stress, whereas that of Ningqi0702 significantly decreased by 12%. Both the leaf tissue water content of Bianguo and Ningqi0702 increased by 25% and 18% under 50 mmol·L-1 NaCl conditions, meanwhile, and remained unaffected under salt-osmotic intercross stress. Moreover, FW and leaf tissue water content were positively correlated with Na+ concentration in leaves and stems of Bianguo. However, for Ningqi0702, FW was positively correlated with K+ concentration in leaves and negative relation with Na+ concentration in stems. Both Na+ and K+ concentration had no correlation with leaf tissue water content in Ningqi0702. Compared with the control, the net selective transport capacity for K+ over Na+ (ST value) of Bianguo increased by 84% and 43% under osmotic stress and 50 mmol·L-1 NaCl conditions, respectively, whereas that of Ningqi0702 decreased by 63% and 47%. These findings suggested that, Bianguo is able to accumulate a moderate concentration of Na+ in its leaves and have a strong ability to regulate Na+ and K+ homeostasis to improve water status, thus maintaining plant growth when subjected to drought and salinity. Bianguo possesses some characteristics of halophytes. Ningqi0702 haven’t these characteristics.