Comparative Study On Remediation Of Cadmium-Contaminated Calcareous Agricultural Soil By Two Solanum Specie

In recent years,phytoremediation has been increasingly used in soils contaminated by heavy metals.Compared with traditional physical and chemical remediation methods,phytoremediation is simple in operation,economically and technically can be implemented on a large area,and can increase soil organic matter content and soil Fertility can avoid the secondary pollution caused by physical and chemical remediation and the lack of soil plant nutrients,and has a promising application prospect.The core of phytoremediation lies in the use of heavy metal super-enriched plants to remove heavy metals in the soil.In this paper,solanum is used as a test plant for calcareous soil contaminated with heavy metal cadmium.Solanum is a family of Salicaceae,which belongs to the family of one year or perennial The herbaceous plant,solanum is a new type of heavy metal super-enriched plant that has a strong tolerance to heavy metal cadmium compared to other plants.Therefore,in this study,two genotypes of solanum nigrum and solanum alatum,were planted in solanum nigrum and solanum alatum by setting different cadmium concentration gradients?T1-T5?and real contaminated soil samples?M1-M4?in greenhouse pot experiments.By analyzing their growth and physiological indicators Interaction with the composition of soil solutions and changes in heavy metal content,The results as follows:?1?Two kinds of solanum at different Cd concentrations?T1-T5?and compound pollution?M1-M4?.The cadmium content,enrichment factor?BCF?and transfer factor?TF?in roots,stems,leaves,and fruits all show the characteristics of super-enriched plants.The plant height of solanum alatum is higher than that of solanum nigrum in different treatment groups,and its growth is not significantly inhibited by heavy metal Cd.Although the plant height of solanum is reduced,the change between groups is not significant.Under different cadmium stresses,the two genotypes of solanum had a cadmium content of 25 mg·kg^-1?T3 treatment group?above 100 mg·kg^-1 in the leaf or aboveground.In the case of single cadmium pollution or compound pollution,the main organs of cadmium-enriched solanum are roots and leaves,and the sum of accumulated cadmium content in stems,leaves,and fruits of solanum is greater than that in roots.In summary,under different cadmium stress,solanum solanum showed a slight downward trend in plant height and biomass dry weight,but the contrast between the groups did not change significantly,indicating that it was less affected by the change in cadmium concentration,while the root,stem,The content of cadmium in leaves and fruits is greater than that of solanum alatum solanum.Compared with the solanum alatum plant height and biomass under different concentrations of cadmium stress there is a tendency to increase,indicating that the plant has less heavy metal cadmium content,but can promote the growth of its solanum nigrum plant.Better enrichment advantage.?2?The phytoremediation of heavy metal cadmium contaminated soil by the two genotypes of solanum will significantly reduce the content of heavy metal Cd in the soil.Phytoremediation will also affect the internal connection of the composition of the soil solution,and changes in the composition of the soil solution will affect the heavy metals in the soil solution Migration capacity and bioavailability.As the pollution of heavy metals increases,the roots of solanum plants secrete molecular organic acids to provide organic ligands for heavy metals and form complexes with heavy metals.In the calcareous soil,Ca ion and Cd ion adsorption competition,the presence of a large amount of CaCO₃ in the soil and the neutralization of organic acids secreted by the root will ensure that the pH will not be significantly reduced.EC under high oxidation conditions is easier to convert heavy metals into water-soluble or exchanged state than under low EC reduction.The DOC in the soil solution easily forms complexes with heavy metals,enhancing their mobility and bioavailability.Through the activation of heavy metals,the absorption of heavy metals by solanum plants is enhanced.Therefore,the effective state of heavy metal cadmium in the soil is dynamically regulated by pH,Ca²⁺,and DOC in the soil.The difference between the composition of the soil solution of the solanum nigrum and the solanum alatum is not obvious,but the solanum nigrum has a higher cadmium content in the soil solution than the solanum alatum,and The effective state content of heavy metal cadmium is subject to the dynamic adjustment of pH,Ca²⁺and DOC in the soil solution,what can be absorbed by plants is the effective state of heavy metals,indicating that solanum ningrum can absorb heavy metal cadmium through the effect of soil solution on the effective state content of heavy metal cadmium?3?When the two genotypes of Solanum nigrum are subjected to heavy metal cadmium stress,the activation of heavy metals in the soil is absorbed by plants.Heavy metal Cd can induce the production of reactive oxygen species?ROS?free radicals in plants,and the content of superoxide anions in solanum plants increases,Oxidative damage to plants and oxidative decomposition of membrane lipids,malondialdehyde?MDA?as its product content will also increase.In order to deal with the oxidative damage to plants caused by free radicals induced by heavy metals Cd,solanum has a set of anti-oxidation mechanism.When the oxidative damage is aggravated,plant cells will accumulate proline in large amounts,and proline will form Cd-proline by heavy metals The complexes also chelate hydroxyl free radicals and reduce the oxidative damage of heavy metals and free radicals to plants.Superoxide dismutase?SOD?,peroxidase?POD?and catalase?CAT?together form the antioxidant system of solanum.Superoxide dismutase will decompose O^2-into H₂O₂ and O₂.Catalase will decompose the generated H₂O₂,POD will decompose harmful peroxides,in order to resist the oxidative damage of plants caused by free radicals.The content of MDA and OFR in solanum alatum solanum is higher than that of red solanum.Under different concentrations of cadmium stress,heavy metals induce the production of superoxide free radicals.MDA as a product of membrane lipid peroxidation decomposition has a high content,indicating that the solanum alatum,The anti-oxidation mechanism is weaker than solanum nigrum solanum.The anti-oxidation mechanism of solanum nigrum solanum reduces the oxidative stress of heavy metal cadmium and reduces the damage to solanum.