Effects of Soil As on Cell Membrane Permeability and Antioxidant Enzymes Activities of Panax notoginseng

Pot experiments were conducted in order to understand effects of arsenic (As) (As5+:0, 20, 80, 140, 200, 260mg/kg) on cell membrane permeability, malondialdehyde content (MDA) and antioxidasessuperoxide dismutase (SOD), perosidase (POD), catalase (CAT) and polyphenol oxidase (PPO) of P. notoginseng at growing stage and apply theory and practice basis for resistance of P. notoginseng to As stress. The results showed that:(1) Cell membrane permeability and MDA content of leaves of P. notoginseng increased with the increase of As mass fractions. Cell membrane permeability and MDA content increased by 160.5% and 48.8% under two-year consecutive 260mg/kg As treatment, respectively. Positive relationship between MDA content and As treatment was observed. (2) Activities of SOD and PPO kept stable and activity of POD decreased under the first year As stress. SOD activity of leaves of P. notoginseng increased and then decreased with the increase of As mass fraction two-year consecutive As stress. SOD activity decreased by 35.7% under 260mg/kg As treatment comparing with control. POD and PPO activities decreased with the increase of As mass fraction. CAT activity increased with increase in As treatment concentrations at the first year and two-year consecutive As stress. In general, the results indicate that cell membrane of leaves of P. notoginseng was damaged under As stress with protein and sugar metabolisms produced anti-stress effects to some extent, POD and PPO activities inhibited and SOD and CAT acted as key enzymes to eliminate peroxidation. There are accumulating effects of two-year consecutive As stress on leaves of P. notoginseng.