| The cadmium(Cd)is regarded as one of most important environmental pollutant in China.It is toxic for human and other animals.Nowadays,many methods have been developed to remediate Cd-contaminated soils in China.Plant remediation method is the most promising one.In this study,three fast-growth poplar species Populus cathayana,Populus beijingenesis 4 and Populus chifeng were selected to develop a suitable tree for remediation of Cd.We compared the biomass production,Cd content,translocation factor(T_f),tolerance index(T_i)and bioconcentration factor(BCF)of three poplar species.We also examined the ultracellular structure of leaves,photosynthetic activity and antioxidant activity of three poplar species under Cd stress.The study showed that all plants had lower biomass,chlorophyll contents and photosynthetic activity and comparatively higher antioxidant activity under Cd stress compared with control.P.cathayana was less affected by Cd with more biomass,higher photosynthetic rate(A),transpiration rate(E)and chlorophyll contents,whereas P.chifeng and P.beijingenesis4 have less biomass,lower A and E rate and chlorophyll contents.Furthermore,P.cathayana has higher T_f and T_i compare to P.beijingenesis 4and P.chifeng and higher BCF than P.chifeng.P.beijingenesis 4 has highest BCF which probably is the reason why P.beijingenesis 4 had more Cd toxic symptoms than other two species.Transmission electron microscopy(TEM)results affirmed that the subcellular structures of P.beijingenesis 4,especially the thylakoids structure and chloroplast membranes were greatly disrupted,while the subcellular structures of P.cathayana was least affected,the chloroplast was hardly affected and it had visible shape and thylakoid structure as compared to other two species.On the basis of above results,we concluded that P.cathayana is a suitable candidate for Cd remediation with maximum growth,biomass production and higher Cd accumulation. |
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