Effects Of Copper And Zinc Stress On The Growth Of Cinnamomum Camphora(L.) Presl

With the rapid development of industry,agriculture and mining,the problem of soil pollution has become more and more prominent.Polluted land use is an urgent problem to be solved.It is difficult to remedy heavy metal pollution in soil by physical or chemical methods,which is costly and may cause irreversible damage to the soil itself.Phytoremediation is an effective method to remedy heavy metal pollution.Cinnamomum camphora is widely used in urban landscaping and afforestation,as well as characteristic economic tree species.This study selected one-year-old cuttings of Cinnamomum camphora as experimental materials,using pot experiment method to study the effects of different concentrations of heavy metals Zn?100mg/kg,500mg/kg,1000mg/kg?,Cu?50mg/kg,150mg/kg,450mg/kg,900mg/kg?,and mixed treatment?Cu450 mg/kg+Zn1000mg/kg?on the growth and physiology of Cinnamomum camphora,as well as the enrichment and migration characteristics of heavy metals in different organs.In order to reveal the toxic mechanism of heavy metals on Cinnamomum camphora,the mechanism of the reaction of Cinnamomum camphora on heavy metal stress Cu and Zn was understood,and its ability to heavy metals resist Cu and Zn stress was evaluated,which provided a theoretical basis for the selection of tree species for the restoration of contaminated land.The research results are as follows:?1?The effects of Cu,Zn stress on theMorphological index of Cinnamomum camphora were different.Cu?450mg/kg and Zn?500mg/kg promoted the growth of plant height,900mg/kgCu and 1000mg/kgZn inhibited the growth of plant height,while Cu?150mg/kgand Zn?500mg/kg promoted the growth of stem and root length of Cinnamomum camphora,and 450mg/kgCu,900mg/kgCu and 1000mg/kgZn inhibited the growth of stem and root length of Cinnamomum camphora.Compared with 450mg/kgCu and 1000mg/kgZn treatments,there were significant differences in ground diameter and root length,but no significant differences in plant height.Therefore,low concentration of Cu and Zn promoted the growth of camphor,high concentration of Cu and Zn inhibited the growth of camphor.There was a competitive relationship between Cu and Zn.Cu could reduce the toxicity of Zn.Cinnamomum camphora could grow normally at concentrations of Cu?450mg/kg and Zn?500mg/kg..?2?Cu and Zn stress can reduce the content of chlorophyll and photosynthetic characteristics of Cinnamomum camphora.Chlorophyll content of Cinnamomum camphora under Cu and Zn stress increased firstly and then decreased with the prolongation of stress time.Chlorophyll content of each treatment reached the maximum at 7 days after treatment.Compared with the treatment for 90 days,there was no significant difference in chlorophyll content of camphor leaves at concentrations of Cu?450mg/kg and Zn?500mg/kg,but the chlorophyll content decreased significantly at concentrations of1000mg/kgZnand450mg/kgCu+1000mg/kgZn.Thetranspirationrate?Tr?,net photosynthetic rate?Pn?and stomatal conductance?Gs?of leaves decreased with the increase of treatment days and concentration,but the change trend of intercellular CO₂concentration?Ci?was opposite.?3?The effects of Cu and Zn stress on SOD activities,POD activities,MDA contents and protein content in leaves and roots of Cinnamomum camphora were different,and the contents of MDA,SOD activities,POD activities and protein in leaves were higher than those in roots.The activities of POD and SOD in leaves and roots increased gradually at low concentrations?Cu?150mg/kg and Zn?500mg/kg?and decreased at high concentrations?Cu?450mg/kg,Zn1000mg/kg and 450mg/kgCu+1000mg/kgZn?.The content of MDA continued to increase with the extension of stress time.?4?Under the stress of Cu and Zn,the contents of Cu and Zn in different parts of Cinnamomum camphora increased with the increase of stress concentration.The contents of Cu and Zn in different parts of Cinnamomum camphora were in the order of root>stem>leaf.Except for 50mg/kgCu and 500mg/kgZn,the migration coefficient is less than1 under other concentrations.Except for 450mg/kgCu treatment,the enrichment coefficient of the top and root parts of the other treatments was greater than 1.The content of heavy metals in different parts of Cinnamomum camphora is mainly concentrated in the roots.