The Study On Endurance Of Exotic Weed (Gynura Crepidioides Benth) To Heavy Metal Pollution

With field sampling and system analysis to 8 species of hydrophytes grown in water around Siheshan industrial area of Wuhu, Gynura crepidioides Benth which has stronger resistance in the primary exploration was selected as the research object. The effects of Cu and Zn pollution on the growth and eco-physiological indices of Gynura crepidioides Benth were studied by water cultivation and pot-planting method. We studied the relationships of four kinds of soil enzyme activities in the polluted soil to heavy metal Cu,Zn.Respectively,The endurance mechanisms of Gynura crepidioides Benth to Cu and Zn pollution were investigated.As a result,the scientific managing basis of remediation for water bodies and wetland polluted by heavy metal had been brought forward through this study.The main conclusions as follows:1. 8 species of hydrophytes had not appeared the poisoned symptom in the water environment in which the heavy metal content was high, such as the descent growth rate or the death. And the growth of hydrophytes were fine, they showed certain resistance to Cu,Pb,Cd,Zn.2.In Hoagland cultivation, when pollution caused by Zn at low content(<10mg?L-1), Gynura crepidioides Benth was damaged slightly. With the Zn content increasing, the activities of protection enzyme reduced and appeared disproportion, such as SOD, POD and CAT in cell, which caused active oxygen product and the scavenging system were unbalanced. It also caused the MDA massive accumulation and the cell membrane penetrability increasion, the desmoenzyme and the original metabolism region destruction, and the chlorophylls content remarkable descentent, the biomass also reduced obviously. Thus the decrepitude and death of plant were accelerated.3.In Hoagland cultivation, when pollution caused by Cu at low content(<5mg?L-1),the plant external injury of Gynura crepidioides Benth was not obvious, even promoted the growth and the protection enzyme in cell such as SOD,POD and CAT increasing. But with the Cu level increased, the plant grew slowly, the biomass descented, and the chlorophylls level descenting.