Phytoremediation Potential And Tolerant Mechanism Of Macleaya Cordata In Cd Contaminated Soil

Heavy metal pollution is a major concern of the public due to their threats to the safety of food chains. Phytoremediation is a cost-effective and environmental friendly technology which aims to extract or remove metals from contaminated soil. A 60-days pot experiment was conducted using Macleaya cordata as plant material to investigate the phytoremediation potential and anti-oxidative responses of Macleaya cordata under different Cd stress. The results indicated that Macleaya cordata have ralatively high accumulation characteristics for Cd. The maximum Cd concentration in plant was 91.93 mg/kg, which is close to the standard values (100mg/kg) of Cd hyperaccumulators. Significant growth inhibition phenomenon and toxic symptoms were not detected in the experiment. The high biomass of the plant provided high accumulation capacity for Cd. The maximum extraction amount of Cd was 216 ?g·plant-1, suggesting that this species had potential for phytoremediation of Cd contaminated soil. The Cd concentration in different part of plant follow the order (root > stem> leaf). A slight increase of chlorophyll (CHL) content was observed in Cd10 treatment. The plant was confirmed to have relatively high tolerance to the Cd stress on the basis of tolerance indexes (TI), relative water content and CHLa/CHLb ratio. It was confirmed that the above ground part of the plant was less tolerant to Cd stress when compared to the root by the data of (TI). The different effects on the antioxidative enzymes which Cd brought to the plant were observed in the experiment. Macleaya cordata could maintain high level of superoxide dismutase (SOD) activity under Cd stress, indicating strong tolerance capacity for reactive oxygen species (ROS) in plant cells. Catalase (CAT) activity and ascorbate peroxidase (APX) show a certain range of decline in the experiment compare to the control. And peroxidase (POD) activity in leaves changed irregularly when compared to the control. The malondialdehyde (MDA) content increased as Cd concentration elevated compared to the control.In addition, as an inedible crop with relatively high economic value, Macleaya cordata have shown the advantage of high biomass and tolerance under Cd stress, which can provide a new plant resource for sustainable phytoremediation.