The Primary Study Of Drought Resistance And The Biologic Toxicity Of An Invasive Plant, Erigeron Canadensis L.

Erigeron canadensis L. is an invasive plant widely distributed in China. This study has researched its drought resistance and the biologic toxicity for evaluating its invasion.In this study,An invasive plant,E. canadensis L. was treated with the osmotic stress solution PEG 6000. The relation between the plant physiology indexes and plant drought resistance was determined. The results showed that the content of MDA,proline and soluble protein,activities of SOD and POD have changed differently with different drought stress. Under different drought stress,the content of MDA and the content of soluble protein increased,a great quantity of proline have been accumulated, the activity of POD increased. The activity of SOD increased in the early phase of drought stress,decreased in the metaphase and increased in the late phase. These results indicated that E. canadensis L. have various drought resistance mechanisms and can grow in different habitats.In the present study we tested the allelopathic effects of different concentrations aqueous over ground and underground part extract of E. canadensis L. on seed germination,root of seedling growth and the changes of cell membrane permeability in Oryza sativa L. and Triticum aestivum L. by the methods of bioassay. The results showed that all aqueous extracts have allelopathy on receptor plants. The aqueous root,stem and leaf extract of E. canadensis L. inhibited seed germination and root growth in a certain extent. The allelopathy of E. canadensis L. delayed seed germination and damaged the cell membrane of receptor plants.By micronucleus test technique of Vicia fabra cells,the present study have studied the cell toxicity of E. canadensis L.. The results showed that the aqueous extracts of E. canadensis L. have produced genetic toxicity and could inhibit mitosis. With the increase of concentration and prolonging of action time,mitotic indexes decreased and frequencies of micronuclei increased. There has been some abnormal phenomenon of root tip cells such as micronuclei,Chromosome Bridge,chromosome break,chromosome lag,chromosome conglutination and three pole divide.The results showed that the invasive plant E. canadensis L. has strong drought resistance,allelopathy and biologic toxicity.