Accumulation Characteristics And Physiological Responses Of Amorpha Fruticosa To Lead And Cadmium Stress

Affected by the rapid development of industry,the black soil area of Northeast China also faces the impact of heavy metal pollution.In this paper,Amorpha fruticosa,which is widely planted on the ridges in the black soil area of Northeast China,is used as the research material.By analyzing the effects of Pb and Cd stress on the growth,physiology characteristics and photosynthetic characteristics of Amorpha fruticosa.Determine the contents of Pb and Cd accumulated in various organs of Amorpha fruticosa,calculate the enrichment coefficient and transport coefficient of Pb and Cd,evaluate the stress resistance of Amorpha fruticosa to Pb and Cd,and explore the potential and feasibility of Amorpha fruticosa for remediation of Pb and Cd polluted soil.To provide theoretical basis and technical guidance for planting Amorpha fruticosa as a remediation tree species in heavy metal contaminated areas.The main conclusions of the experiment are as follows:1.Pb and Cd stress promoted the growth of root length,plant height and ground diameter as well as biomass accumulation of Amorpha fruticosa to varying degrees,when the level of lead and cadmium stress was low（Pb<600 mg/kg、Cd<10 mg/kg）.The higher the lead concentration,the smaller the root length,plant height,ground diameter and biomass,when the Pb concentration was greater than 600 mg/kg and the Cd concentration was greater than 10mg/kg.2.Pb and Cd stress significantly increased the MDA content,soluble protein content and free proline content of Amorpha fruticosa leaves.Compared with CK,high concentration of Pb stress（Pb>3000 mg/kg）significantly inhibited the POD activity of Amorpha fruticosa leaves,other concentrations of Pb and Cd stress did not significantly inhibit the SOD activity,POD activity and CAT activity of Amorpha fruticosa leaves.3.Pb stress significantly inhibited the chlorophyll content of leaves of Amorpha fruticosa,under Cd stress,the chlorophyll content showed a trend of increasing first and then decreasing,with a maximum value when the Cd concentration was 10 mg/kg.Pb stress significantly inhibited the net photosynthetic rate,stomatal conductance,intercellular CO₂concentration and transpiration rate of Amorpha fruticosa leaves.Under Cd stress,the net photosynthetic rate,stomatal conductance and transpiration rate first increased and then decreased,intercellular CO₂concentration decreased significantly when Cd concentration was greater than 40 mg/kg.4.Under the stress of different concentrations of Pb and Cd,the accumulation of Pb and Cd in each organ was root>stem>leaf,and the content of Pb and Cd in each organ increased significantly with the increase of soil Pb and Cd concentration.Under Pb stress,the enrichment coefficient of the aboveground part,the enrichment coefficient of the underground part and the migration coefficient first increased and then decreased with the increase of Pb concentration,and the enrichment coefficient of the underground part gradually decreased with the increase of the concentration.Under Cd stress,the aboveground enrichment coefficient and underground enrichment coefficient increased gradually with the increase of Cd concentration,while the migration coefficient first increased and then decreased with the increase of Cd concentration.In summary,Amorpha fruticosa has strong resistance to Pb and Cd,and can grow normally under low concentrations of lead and cadmium stress（Pb<600 mg/kg、Cd<10mg/kg）;It has a weaker Pb accumulation and migration ability.The accumulation ability of Cd is strong,but the migration ability is weak.Therefore,Amorpha fruticosa still has great potential as a vegetation restoration tree species and afforestation tree species in heavy metal pollution areas.