Studies On The Resistance And Remediation Potential Of Three Legumes To Cu Tailings

Three woody species of legume,Sophora japonica,Albizia julibrissin,Albizia kalkora were used as experimental materials to investigate the effects of Cu on the growth and tolerance physiology of plants and their effects on soil remediation potential.The aim of this study was to provide theoretical and technical support for contaminated environmental remediation of heavy metal.The main results were as follows:(1)Effects of different portions of Cu tailings on the growth and Cu accumulation of three woody species of legume were studied.The results showed that with the increase of Cu portions,plant height and root length of S.japonica were decreased compared with CK(P<0.05).Plant heights of A.julibrissin and A.kalkora were increased first and then decreased.The root lengths of A.julibrissin increased,while,A.kalkora decreased.The tolerance indexes of S.japonica and A.kalkora under the treatment of 100%Cu tailings were the lowest compared with those of the control.However,the tolerance index of A.julibrissin increased with Cu concentration increased.Cu accumulation of three legume species were gradually increased as the portions of Cu tailings enhanced and Cu content in the roots of A.kalkora under pure Cu tailings was highest.translocation factors of S.japonica and A.kalkora decreases with the increase of Cu tailings,while,those of A.julibrissin were upward trend and higher than that of the control.The bioconcentration factors of above-and underground parts part of S.japonica and A.julibrissin increased first and then decreased,while,the bioconcentration factors of the roots of A.kalkora in 100%Cu tailings up to 1.214.The results showed that three species of legume had stronger tolerance and accumulation ability,the tolerance of A.julibrissin to Cu tailings was the highest,and the Cu accumulation ability of A.kalkora was better than other two species.(2)As the increase of Cu tailings,the chlorophyll contents of S.japonica,A.julibrissin and A.kalkora were first increased and then decreased.The electric conductivity in above-and underground partsof S.japonica and aboveground parts of A.kalkora was first increased and then decreased,while,aboveground parts of A.julibrissin increased.The electric conductivity in the underground parts of two species of Acacia showed significantly upward trend.MDA content in the aboveground parts of S.japonica and underground parts of A.julibrissin showed a downward trend.SOD and POD activities in the aboveground parts of S.japonica decreased,SOD activity in the underground parts was increased,while,POD activity in underground was decreased and then increased.SOD and POD activity of A.julibrissin and A.kalkora decreased as Cu tailings decreases.The results showed that the high portions of Cu tailings had a certain toxic effect on plants,and the growth of plants was inhibited.(3)The research of three woody species of legume and Koelreuteria bipinnata compound cultivation in Cu tailings found that the plant height,root length,shoot and root dry mass and tolerance index of S.japonica and A.julibrissin in compound cultivation were higher than that of monoculture.However,the growth index of A.kalkora and K.bipinnata were lower than monoculture.Except Cu content in the underground parts of S.japonica in compound cultivation was higher than that of monoculture,Cu contents of other plants were lower than that of monoculture.Cu contents in aboveground parts of K.bipinnata in K.bipinnatawith S.japonica and A.kalkora compound cultivation were higher than that of monoculture,while,in K.bipinnatawith A.julibrissin treatment,lower than that of control.The bioconcentration factors of S.japonica in compound cultivation was higher than that of single planting,while,the bioconcentration factors of underground parts of K.bipinnata,A.julibrissin and A.kalkora were lower than monoculture.The results indicated that the three species of leguminous plants with K.bipinnata compound cultivation were more effective than the monoculture in the promote plants tolerance to Cu tailings and Cu accumulation.(4)The results of the study on the compound cultivation of three woody legume species with K.bipinnata in the Cu tailings showed that the soil dehydrogenase,urease and phosphatase in each treatment group were higher than those in the control(not cultivated any plants).The most significant difference in soil dehydrogenase activities were found in the compound cultivation of K.bipinnata with S.japonica and A.julibrissin.Urease activity of all treatments increased significantly and phosphatase activity was in single cultivation of K.bipinnata compared with the control and increased significantly.The catalase activities of A.julibrissin and A.kalkora in monoculture were higher than that of the control,while,K.bipinnata and S.japonica in monoculture were lower than the control.The catalase activities in the cultivation substrate of three woody legume species and K.bipinnatacompound cultivation were increased compared with that not a plant Cu tailing.The results indicated that the compound cultivations could improve the activity of catalase in the cultivation substrate.The soil electrical conductivity,pH value and soil Cu concentration of each treatment group were lower than those of control under Cu copper tailings stress.The results indicateded that the three woody legume plants with K.bipinnata could improve the activity of soil enzyme and improve the physical and chemical properties of cultivation substrate.