Effects of NaCl stress on the growth and antioxidant system of peppermint(Mentha piperita L.)

In order to discuss the physiological characteristics of salt tolerance in peppermint and provide the theoretical basis for its development and utilization in saline areas, the effects of different concentrations of NaCl(0, 100,150, 200, 250 mmol/L) on the growth and antioxidant system of peppermint were studied. The results showed that peppermint could keep normal growth under 100 and 150 mmol/L NaCl stress by up-regulating the activities of antioxidant enzymes(SOD, POD, CAT, APX) and the contents of non-enzymatic antioxidant(AsA, GSH, carotenoid) to alleviate NaCl-induced oxidative stress. With the increase of concentrations of NaCl treatment(200 and 250 mmol/L), the activities of antioxidant enzymes and the contents of non-enzymatic antioxidant initially increased but then decreased within the duration of NaCl treatment, which resulted in the growth inhibition of peppermint. The higher the concentrations of NaCl, the more the enzyme activities and antioxidant contents reduced. In all, the results demonstrated that peppermint could tolerate 150 mmol/L NaCl stress. Under this concentration of NaCl stress, peppermint had stronger antioxidant capacity and could maintain normal growth. However, peppermint plants would be damaged under higher concentrations of NaCl stress.