Effect of salt stress on the growth,antioxidant enzyme activities,and ion uptake of two Chinese cabbage cultivars

A pot experiments was conducted to investigate the effects of salt stress on dry weight,activities of SOD,POD,and CAT,as well as ion uptake of two Chinese cabbage cultivars(Zhebai 9 and Zaoshu 5).The two Chinese cabbage cultivars were grown on a coastal saline soil applied 0,1,1.5,2.0,2.5 and 3.0 NaCl g /kg.The dry weight in the aerial part of Zaoshu 5 significantly decreased with increase of salt concentrations above 1.5 g/kg,while for Zhebai 9 no significant difference was observed between 1.0 and 2.5 NaCl g /kg.The activities of SOD,POD and CAT in both cultivars were greater at lower salt levels,but were lower at higher salt levels.The highest activities of SOD,POD and CAT in Zhebai 9 were obtained at 2.5,2.0 and 2.0 NaCl g/kg,respectively;while those in Zaoshu 5 were obtained at 1.5,1.0 and 1.0 NaCl g/kg,respectively.Furthermore,the Na+ contents in the aerial part of both cultivars significantly increased with increasing NaCl concentrations,while the contents of K+,Ca2+,and Mg2+ significantly decreased with increasing NaCl concentrations.Under the same salt concentration,the contents of K+,Ca2+,and Mg2+ as well as K+/Na+ ratio in Zhebai 9 were significantly higher than those in Zaoshu 5.