铅胁迫下桤木幼树生长与抗性生理的变化及铅富集转移特性

[Objective]To evaluate the potential of Alnus cremastogyne for remediation of Pb-contam inated soils by studying the physiological changes in growth and resistance,and the enrichment and trans fer of Pb in young Alnus cremastogyne trees under Pb stress.[Method]A six-month pot experiment was carried out in soil with different Pb concentrations(0,50,100,200 and 400 mg/kg)using one-year-old Alnus cremastogyne trees as experimental materials.The plant height,basal diameter,biomass,leaf peroxide marker content,osmoregulatory substance content and antioxidant enzyme activity,as well as the contents of nitrogen(N),phosphorus(P),potassium(K)and lead(Pb)in each organ(absorbing root,transporting root,trunk,branch and leaf)were measured,and the Pb enrichment coefficient and Pb transport coefficient of each organ were calculated under the different treatment.[Results]①With the increase of Pb concentration,the total biomass of the plant showed a decreasing trend.When the Pb concentration was less than 50 mg/kg,it promoted the plant height and basal diameter of young Alnus cremastogyne trees.When the Pb concentration was more than 200 mg/kg,the plant height,basal diameter and the total biomass of the young Alnus cremastogyne trees were all significantly suppressed.The activities of SOD(superoxide dismutase),POD(peroxidase)and CAT(catalase)tended to increase and then decrease with the increase of Pb concentration,the contents of H2O2(hydrogen peroxide)and MDA(malondialdehy de)increased significantly,and the contents of Pro(proline),SS(soluble sugar)and SP(soluble protein)tended to increase and then decrease.The activities of antioxidant enzymes(SOD,POD and CAT)increa sed significantly at Pb concentrations higher than 50 mg/kg,and there was no significant effect on osmo regulatory contents(Pro,SS and SP)at Pb concentrations lower than 50 mg/kg.(iii)Nitrogen content in transport roots of young Alnus cremastogyne trees increased significantly with increasing lead concentrati on;phosphorus and potassium content in leaves and phosphorus content in absorbing roots decreased sig nificantly,while nutrient content in branches and trunks did not change significantly.④With the increase of Pb concentration,the Pb content in each organ of young Alnus cremastogyne trees increased significantly,and the increase was absorbing root＞transporting root＞trunk＞leaf＞branch.The transfer factor(T F)of young Alnus cremastogyne trees decreased significantly with the increase in Pb concentration,and the Pb content and bioconcentration factor(BCF)in the roots of young Alnus cremastogyne trees were significantly higher than those in other organs.[Conclusion]Alnus cremastogyne is not a Pb-enriched plant and does not have outstanding Pb-transporting ability,but low concentrations of Pb stress will promote the growth and development of Alnus cremastogyne.Because of its wide distribution and rapid growth,Alnus cremastogyne can be used as a silvicultural species in areas with low concentrations of lead pollution.