Influence of salt stress on ecophysiological parameters of Periploca sepium bunge

An experiment was carried out to investigate the effect of salt stress on Periploca sepium Bunge seedlings using three levels of salinity, 50 mmol/L, 100 mmol/L, and 200 mmol/L sodium chloride (NaCl) solution. The results showed that growth parameters and net photosynthetic rate (Pn), stomatal conductance (Gs) of Periploca sepium Bunge were enhanced under low salinity levels (50 mmol/L NaCl), which reduced strongly with increasing salinity levels. Under 100 mmol/L NaCl and 200 mmol/L NaCl stress, the decline of Pn was mainly caused by non-stomatal factors. The water use efficiency (WUE), apparent light use efficiency (LUE), carboxylation efficiency (CUE) were enhanced under low salinity levels (50 mmol/L NaCl), the maximum value of WUE was observed at 100 mmol/L NaCl, the minimum value of WUE was observed at 200 mmol/L NaCl, the LUE, CUE were reduced by 52% and 47%, at 200 mmol/L NaCl, respectively, compared to control. Activities of the antioxidative enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were enhanced by low salinity treatment (50 mmol/L NaCl), but CAT activity decreased at 200 mmol/L NaCl stress. Malondialdehyde (MDA) was non-significant compared to the control under low salinity levels (50 mmol/L NaCl), the maximum value was observed at 200 mmol/L NaCl. These results suggest a possibility to improve saline soil utilization of Periploca sepium Bunge in Yellow River Delta region.