Effect of Pb and Cd Stress on the Growth of Potato and Its Antioxidase System

With the potato variety Xishu 1 as the test materials, this paper adopted tissue culture to study the effect of Pb and Cd stress with different mass fractions on potato growth and the antioxidase system. The results showed that under the stress of Pb （200 mg/kg） and Cd （20 mg/kg）, growth of potato had no obvious difference with that in control group; under the stress of Pb （ 〉200 mg/kg） and Cd （ 〉20 mg/kg）, potato growth suspended, and its physiological indexes such as dry weight, plant height, root number, root length were inhibited obviously. With the increasing mass fraction of Pb, relative electrical conductivity, MDA and proline of potato leaves showed the tendency of increase, and the results in high mass fraction treatments showed significant difference with those in the control group （P 〈 0.05 ）, CAT, POD and SOD activity of leaves increased greatly with the increasing mass fraction. In the Pb stress treatment （200 mg/kg）, relative electrical conductivity, MDA and proline of potato leaves showed no obvious difference with those in the control group, and the results in high mass fraction treatments were significantly higher than those in the control group （ P 〈 O. 05 ）, CAT and SOD activity increased greatly with the increasing mass fraction （ P 〈 0.05 ）. Under the stress of Pb and Cd, synthesis of soluble protein in potato leaves was strongly inhibited. The results showed that potato was tolerant to Pb and Cd of lower mass fraction, and damage of potato caused by Pb and Cd stress could be relieved by improving activity of antioxidase and reducing peroxidation of membrane lipid, and the tolerance reduced with the increase of stress.