Effects of Na2CO3 and NaCl stresses on the antioxidant enzymes of chloroplasts and chlorophyll fluorescence parameters of leaves of Puccinellia tenuiflora (Turcz.) scribn.et Merr.

Abstract

Antioxidant enzymes in chloroplasts and chlorophyll fluorescence parameters of leaves of Puccinellia tenuiflora (Turcz.) scribn.et Merr. under isotonic Na2CO3 and NaCl stresses were studied. Ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities showed a similar increasing trend and then decreased with the decreasing osmotic potential of culture solution, peaking at −4.74 × 105 Pa under NaCl stress and at −3.40 × 105 Pa under Na2CO3 stress. APX, glutathione transferase and SOD activities were higher under NaCl stress than those under Na2CO3 stress, and higher activities of antioxidant enzymes in chloroplasts were accompanied by lower MDA content under NaCl stress. F v/F m, F v/F o and F v′/F m′ all initially increased and then decreased with the decreasing osmotic potential of culture solution, while Φ PSII, qNP and HDR showed a constant increase. F v/F m, F v/F o, Φ PSII and qNP under NaCl stress were also shown to be higher than those under Na2CO3 stress. The present study suggested that acidity played an important role in the hurt toPuccinellia tenuiflora seedlings, which was due to higher activities of antioxidant enzymes, qNP and Φ PSII, and the Na2CO3 resistance to Puccinellia tenuiflora was also supposed to be less than NaCl resistance in present work.