Effects of salt stress on Nitraria roborowskii growth and physiological characteristics of stress resistance

A pot experiment was conducted to study the influences of different NaCl concentrations (0, 50, 100, 200, 400 mmol x L(-1)) on the growth, leaf hydrogen peroxide (H2O2), malonaldehyde (MDA) content, superoxide dismutases (SOD), catalases (CAT), peroxidase (POD), ascorbate peroxidase (APX) enzymes activity, water potential, soluble sugar and proline contents of Nitraria roborowskii. The results showed that the growth of N. roborowskii was not affected at lower NaCl concentrations (< or = 50 mmol L(-1)), while the SOD, POD, CAT and APX activities in leaves of N. roborowskii were increased. However, higher NaCl concentrations (> 50 mmol x L(-1)) restrained the growth parameters of crown area, number of branches, dry mass of leaf, branch and lateral root, and remarkably reduced the SOD, POD and CAT activities, soluble sugar and proline contents in leaves of N. roborowskii. H2O2 and MDA contents in leaves were increased and water potential was reduced with increasing NaCl concentrations.