Effect of Mercury Stress on Growth and Physiological Characteristics of Houttuynia cordata
Mercury(Hg)is one of the main pollutants in agricultural soils in Guizhou Province,but the effect of Hg on the growth and physiological characteristics of Houttuynia cordata has not been reported.To provide theoretical basis for the mechanism of Houttuynia cordata damage caused by Hg stress and the phytoremediation technologies for mercury-contaminated soil,this study explored the growth and physiological characteristics of Houttuynia cordata under different concentrations(0,50,100,200,400,800 mg·kg-1)of Hg stress using soil pot experiments.The results showed that Hg stress had no significant effect on the new root and stem thickness,new root and stem length,and old root and stem thickness of Houttuynia cordata(P＞0.05).However,the old root and stem length of Houttuynia cordata significantly decreased under Hg stress when the Hg concentration reached 800 mg·kg-1(P＜0.05),and the average root and stem length of Houttuynia cordata decreased by 40.57％compared with the control group.The total fresh weight of Houttuynia cordata in each group decreased with the Hg concentration(P＜0.05).The Houttuynia cordata significantly deteriorated under Hg stress when the Hg concentration was higher than 200 mg·kg-1.Mercury stress inhibits the generation of chlorophyll in Houttuynia cordata.The lowest chlorophyll con-tent in Houttuynia cordata under Hg stress occurred in 400 mg·kg-1 Hg concentration.The total chlorophyll,chlo-rophyll a,and chlorophyll b content in Houttuynia cordata reduced by 56.37％,58.88％,and 51.32％compared to the control group,respectively.With the increase of Hg concentration,the superoxide dismutase(SOD)and catalase(CAT)enzymes activities in the leaves of Houttuynia cordata first showed a decreasing trend and then showed an increasing trend,while the peroxidase(POD)enzyme activity in the leaves of Houttuynia cordata showed an in-creased trend.With the increase of Hg concentration,the SOD enzyme activity in the roots and stems of Houttuynia cordata increases,the CAT enzyme activity in the roots and stems of Houttuynia cordata first increases and then de-creases,while the POD enzyme activity in the roots and stems of Houttuynia cordata decreases.The flavonoid con-tent in Houttuynia cordata leaves decreases with Hg concentration(P＜0.05).These results indicated that Hg stress has a toxic effect on Houttuynia cordata,which can damage its growth and development,affect its antioxidant en-zyme system,and inhibit the generation of chlorophyll and flavonoids in Houttuynia cordata.The Houttuynia cor-data has a certain tolerance to Hg stress.Considering its strong adaptability to the growth environment,Houttuynia cordata can be used as a soil remediation plant for Hg contaminated soil with Hg levels less than 200 mg·kg-1.
万方数据
维普
