The Experimental Research On Screening Of Tolerance Test Of Cu Tailings And Remediation Potential In Leguminous Plants

1.The four leguminous plants,Cajanus cajan,Amorpha fruticosa,Cassia tora and Indigofera pseudotinctoria,were selected to be planted in different proportions of Cu tailings sand matrix,respectively.The proportion of garden soil is:100%garden soil?CK?,75%garden soil+25%Cu tailings?1/4Cu?,50%garden soil+50%Cu tailings?1/2Cu?,25%garden soil+75%Cu tailings?3/4Cu?and 100%Cu tailings?Cu?;the germination rate,germination index,vigor index and growth index of four leguminous plants were determined.The results showed that five kinds of substrates had an effect on the germination of seeds,and low concentrations of Cu would be converted into trace elements necessary for plants,thereby promoting the germination of plant seeds,while high concentrations of Cu would inhibit the growth of plants;in the germination rate In the experiment,the germination rate of pigeonpea was the highest,followed by Amorpha,Rhizophora and Cassia.By studying the effects of different contents of Cu tailings on the vigor of the four plant species,the vigor index of the pigeonpea was the highest,followed by Cassia,Rhornes,and Amorpha,but the low concentration of Cu tailings had a significant effect on the Amorpha fruticosa.The vitality index of P.spinulosa had a promoting effect,while it had an inhibitory effect on the vitality indexes of the other two plants.The injury degree of plants could be directly determined from the growth index.The experiment showed that low concentration of Cu tailings sand was helpful for the growth of legumes.The plant height,root length and leaf length of Amorpha fruticosa,Cassia obtusifolia and R.hirsutum under different concentrations of copper tailings sand were lower than those of the control.The results showed that Cu stress had greater damage to the seedlings of the three species.Chaga and Cassia are more suitable for the study of the repair potential of copper tailings.2.The effects of Cu tailing sand with different contents on growth indexes and metal ions of wooden beans and determinants were studied by pot culture.The test results showed that the plant height,dry mass of aboveground part and dry mass of underground part reached the maximum value at 1/4 Cu,respectively increasing by5.23%,23.65%and 6.67%compared with the control group.In 1/2 Cu treatment,the root length reaches the maximum;Tree and plant height and dry weight of the earth have been rising after falling trend,and dry weight of root length,underground and the tolerance index are influenced by different degree,showing that the low concentration of Cu tree seedling growth played a certain role in promoting;From dal and tree of absorption and mobility of metal ions can be seen that,in dealing with the different content of Cu,dal and tree on the absorption of Cu²⁺was gradually rising trend,and most of the Cu²⁺concentration on the ground,only a small part of Cu²⁺were shifted to the ground,and tree of Ca²⁺absorption overall dal a downward trend,and with the increase of Cu tail sand,underground part content of Ca²⁺content is significantly higher than the earth;Compared with the control group,the migration rate of Zn²⁺was generally increased.However,it was determined that the migration rate of Zn²⁺was generally first decreased and then increased compared with the control group,which was 27.44%lower than that of the control group at 1/4 Cu treatment.The results showed that Cu stress was beneficial to the transfer of Ca²⁺and Zn²⁺from the underground to the aboveground in the plant,while the migration rate of Cu²⁺was smaller than that of the control.3.The effects of different contents of Cu tailings on the antioxidant system of Cajanus cajan and Cassia obtusifolia were studied by using potted plants.The results showed that the activity of superoxide dismutase?SOD?in the shoot was not significantly different?P>0.05?,The SOD activity in the subsurface was opposite to that in the shoot.The activities of SOD in the upper and lower parts of the Cassia increased first and then decreased.In the 1/4Cu treatment,they increased by 2.84%and 40.87%,respectively.The activity of peroxidase?POD?in the plant was increased when the concentration of Cu tailings was increased,and it was able to resist Cu stress.With the increase of tailings sand content,the enzyme activity decreased.The activity of Catalase?CAT?in shoots increased gradually compared with the control,but the trend was not obvious.The underground was increased by 7.29%compared with the control in the1/4Cu treatment.The CAT activity in the upper part of the Cassia obtusifolia was lower than that in the control.There is a gradual upward trend in the underground.The trends of MDA and GSH in pigeonpea and Cassia showed a trend of decreasing first and then increasing,and reached the maximum at the time of total Cu treatment.The change of As with A of Cu increased first and then rose with the change of Cu content.The content of AsA in shoots was 11.3?g/g and 10.73?g/g when treated with CK and 1/4Cu respectively.After analysis of variance,it did not reach significant levels,but AsA increased significantly with the increase of Cu content?p<0.05?.The experimental results showed that the resistance of Cudou and Cassia to Cu stress was certain,and the low concentration of Cu would be helpful for the growth of plants as the trace mineral elements needed by plants.4.The results of the experimental study on the seedlings of Cajanus cajan and Cassia were used to show that the content of Cu and Ca ions in the two plant substrates increased gradually with the increase of Cu content,which was consistent with the conductivity trend.The soil enzyme decreased gradually with the increase of Cu content,and reached the minimum value in the total Cu treatment.It showed that under Cu stress,the activity of soil enzyme in the matrix decreased,which was not conducive to the growth of pigeonpea and Cassia.However,compared with the blank soil,the activities of invertase and urease were higher than that of the blank soil,indicating that the two plants played a certain role in promoting the recovery of copper-contaminated soil.