The Physiological Reaction To The Stress Of CD For There Poplar Seedlings

In a pottted plant experiment, three poplar seedlings, Grey poplar (Populus×canescens),Cathay poplars (Populus pseudo-simonii K.) and Zhonglin-46poplar (Populus×euramericana（Dode）Guiner CL.),were treated with0,25,50,100,200,400mg/kgconcentrations of Cd2+, These indices are the content of superoxide radical, malonaldehydeand soluble protein and the improvement of NPT. And, the enrichment level of theconcentration of Cd in the different nutritional organs of poplar seedlings was also examined.Based on the research, The mean results as followed:(1) The enrichment level of the Cd in the roots is all higher than that in leaves accordingto the different concentration of Cd in there poplar seedlings. This result suggests that themain location of the Cd enrichment is root. This may due to the principle that the Cd binds tothe proteins、polysaccharides、riboses and nucleic acids and was integrated into stablemolecules and insoluble organic molecules after entering into the cortical cell. Further, thetransport of the Cd to the overground part of the plants is lower for the deposition of all thesemolecules.(2) The content of NPT，GSH and PC increased in the three poplar seedlings accordingto the increase of the concentration of Cd and the case is higher than the control. Under thesame concentration of Cd, the Pc content of leaves is higher than that of root, The tendency ofthis change in leaves is stronger than that in roots （P<0.05）.These results indicate that theChelating of the PC to Cd is the main mechanisms of the resistance to the heavy iron damagefor the leaf of poplar seedlings(3) The content of MDA and O2ˉ·in the leaf of poplar seedlings was more than that inroot and the content of soluble protein in the root was less than the that in leaves. This showsthat the Ge damages to the leaves were heavier than that to roots. With the increment of theCd concentration, There were over expressed O2ˉ·generated in the poplar seedlings. This madethe Membrane Lipid Peroxidation and more MDA generated. However, There were moresoluble protein bond to the Ge ion under the Ge stress in the root. This made the Ge damagessmaller for the root.(4) The content of the water decreased for the leaves and root after30days of thedifferent Cd treatment. The increase of the Cd in soil made the lower water absorption Further,the water transport to the overground parts was influenced. Finally, the photosynthesis of the leaves were influenced and this is the great reason for the weakness of the grow of poplarseedlings.(5) Based on the experiments, we get that the content of soluble protein in Grey poplarseedlings is higher than that in Cathay poplars and Zhonglin-46，and the MDA and O2ˉwaslower. This shows the less damages of the Cd to the Grey poplar seedlings, or The resistanceof Grey poplar seedlings to Cd is stronger than the others. demonstrates the stronger anti-Cdcapability of the than. Compared to the, the leaves and roots of have stronger absorptivecapability to the Ge. They move the Ge into the plant body and improved the soil. Theresistance of Grey poplar seedlings to Cd was appraised using dry weight of root, stem andleaf. The results showed that the resistance of root was stronger than leaf, which reflected theGrey poplar is a favorable tree to be used as phytoremediation.