Effects Of Drought And Lead Stress On Antioxidant Enzymes Activities Of Robinia Psedoacacia And Amaorpha Fruticosa

The effects of heavy metal Pb and drought stress on antioxidant enzymes activities and malondialdehyde and superoxide bydromium content of Robinia psedoacacia,Amaorpha fruticosa and Amaorpha fruticosa cutted in one-year old trees were studied using pot experiments to reseach their strong resistance for the selection of tree species. This experiment is complete randomized block design. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), malondialdehyde (MDA) and superoxide (O₂^.-) indicator were evaluated in the leaves of Robinia psedoacacia, Amaorpha fruticosa and Amaorpha fruticosa cutted under interaction of different water (RWC=100%(control), 80%, 60%, and 40%, respectively) and lead treatments (0(control), 300, 500, 1000, 2000 and 3000 mg/kg). The results were as follows:1. In the early growth stage, SOD activity of Robinia psedoacacia, Amaorpha fruticosa and Amaorpha fruticosa cutted were increased under drought and Pb stress. In the middle and late growth stage, lower (300 mg/kg) Pb content stress can increase SOD activity of Amaorpha fruticosa and Amaorpha fruticosa cutted.2. In the early and middle growth stage, lower (0-500 mg/kg) Pb stress can significantly impact POD activity of Amaorpha fruticosa. In late growth stage, severe drought (RWC=40%) and lower (300 mg/kg) Pb stress can increase POD activity of Amaorpha fruticosa for cuted, which caused little damage to plant.3. In the early growth stage, under drought and lower (500 mg/kg) Pb stress, CAT activity of Robinia psedoacacia were increased. Under lower (500 mg/kg) Pb stress, Amaorpha fruticosa reached the maximum tolerated levels of Pb. In the middle growth stage, under drought and lower (500 mg/kg) Pb stress, CAT activity of Amaorpha fruticosa were increased. In the late growth stage, drought and Pb stress can increase CAT activity of Amaorpha fruticosa and Amaorpha fruticosa for cutted.4. In the early and middle growth stage, under 40% of RWC and Pb stress, Robinia psedoacacia made high lipid peroxidation. With the lead content increasing, MDA content of Robinia psedoacacia and Amaorpha fruticosa for cutted were decreased under single Pb stress, and caused less damage to plants. In the late growth stage, plants were damaged in severe drought and Pb stress.5. In the early growth stage, under drought and Pb stress, a lot of O₂^.- was produced in plants. In the middle growth stage, O₂^.- content of Robinia psedoacacia and Amaorpha fruticosa for cutted were higher in severe drought and lower Pb stress than other treatments, which affected plant growth.