Response of Pb and Cd on Seed Germination and Seedling Physiologica of Portulaca oleracea

Using Portulaca oleracea as experimental plant, through the hydroponic experiments,the seed germination and seedling physiological indexes under Pb, Cd stress were studied. The results showed that low concentration of Pb treatment had little effect on the seed germination, while severely inhibited under higher Pb concentrations, when the treatment dosage of Pb reached to 2 000 mg/L, seeds lose their germination power. Moreover, low concentration of Cd treatment promoted seed germination, while higher concentration of Cd inhibited seed germination.With the increasing of the Cd concentration,contents of soluble protein, soluble sugar,free proline and activity of SOD, POD, CAT of P. oleracea decline significantly. However, with the increasing of the Cd concentration, the osmotic substances and anti-oxidative enzyme activity increased first and then declined.