Effects on antioxidant enzyme activities and osmolytes in Halocnemum strobilaceum under salt stress

The seedlings of Halocnermum strobilaceum were cultivated in 0.5%hoagland nutrient solution containing 0.0%,0.9%,2.7%and 5.4%of NaCl as well as composite salt(Na;,Ca;,K;,Si;) for 20 days;all the contents are in weight ratio.Succulent level,inorganic ions（Na;,K;）,organics such as betaine,proline,malondialdehyde,and antioxidant enzyme activities including superoxide dismutase（SOD）,catalase（CAT）,peroxidase（POD）,betaine aldehyde dehydrogenase（BADH） were measured to reveal its salt tolerance mechanism.When the composite salt concentration reaches 5.4%,SOD activity level,and MDA content is five times the control group;when it reaches 2.7%,the succulent level of seedlings,and the content of K;in roots is nearly two times the NaCl treatment;the dry weight is more than three times the control group;with the NaCl treatment,MDA is three times the contrast;when the salt concentration is 2.7%,POD reaches the maximum.Results indicate that Si;,K;,and Ca;from composite salt in the roots of H.strobilaceum improved the water-holding capacity.The activities of antioxidant enzyme were raised by the accumulation of proline and betaine,which increased the salt tolerance.The absorption of K;promoted the high ratio of K;/Na;and alleviated the damage of cell membranes of H.strobilaceum,which is associated with osmotic contents such as betaine and proline.