镉、铅、锌复合胁迫对滇杨幼苗富集及转运镉的影响

为探究Cd-Pb、Cd-Zn和Cd-Pb-Zn复合污染的交互效应，以滇杨幼苗为研究对象，通过土培盆栽试验对Cd（50 mg·kg^-1）、Pb （500 mg·kg^-1）、Zn （500 mg·kg^-1）单一及复合胁迫下滇杨富集、转运Cd的特征进行深入分析，旨在为滇杨的矿区修复利用提供依据。结果表明：单一及复合胁迫可降低滇杨幼苗株高增长率，提高其地径增长率，其中Cd-Pb-Zn复合胁迫株高增长率降幅最大（24.45%），Cd-Zn复合胁迫地径增长率增幅最高（317.04%），而滇杨生物量仅在Cd-Pb-Zn复合胁迫时显著下降，降幅为30.28%。与单一Cd胁迫相比，Cd-Pb复合胁迫显著增加滇杨茎中Cd含量，Cd-Zn和Cd-Pb-Zn复合胁迫显著降低滇杨各器官Cd含量；单一Cd胁迫下滇杨Cd积累量为0.32 mg·pot^-1，Cd-Pb胁迫未显著改变Cd积累量（0.34 mg·pot^-1），而Cd-Zn（0.14 mg·pot^-1）和Cd-Pb-Zn胁迫（0.13 mg·pot^-1）显著降低Cd积累量。不同胁迫条件下滇杨Cd富集与转运系数变化规律结果显示，复合胁迫中Pb和Cd的交互作用（Pb×Cd）促进Cd由土壤向滇杨富集，并增强Cd向地上部转运，Pb×Cd表现出协同效应； Zn×Cd抑制滇杨Cd富集，但能提高Cd转运，对Cd富集和转运分别表现出拮抗和协同效应； Pb×Zn×Cd抑制滇杨对Cd的富集和转运，三者复合时表现出拮抗效应。研究表明，滇杨幼苗对Cd-Pb、Cd-Zn复合胁迫具有耐受性，复合胁迫下交互作用类型及作用的植物器官决定了对Cd富集与转运的影响程度。

Effects of Cd, Pb, and Zn combined stress on Cd accumulation and translocation in Populus yunnanensis seedlings

In order to explore the interactions of metals in the combined pollutants Cd-Pb, Cd-Zn, and Cd-Pb-Zn, seedlings of Populus yunnanensis were selected, and the characteristics of Cd enrichment and transport under the single and combined stress of Cd(50 mg · kg^-1), Pb(500 mg · kg^-1) and Zn(500 mg · kg^-1) were analyzed by soil pot experiments, to provide a reference for the restoration and utilization of mining areas where P. yunnanensis occurs. The results showed that:both single and combined stresses significantly reduced the height growth rate of P. yunnanensis seedlings and increased the growth rate of the ground diameter. The height growth rate decreased the most under the Cd-Pb-Zn combined stress(24.45%), and the increase rate of the ground diameter was the highest under the Cd-Zn stress(317.04%). The biomass decreased significantly only under the Cd-Pb-Zn combined stress, with a decrease of 30.28%. Compared with the single Cd stress, the Cd-Pb stress significantly increased the content of Cd in the stem of P. yunnanensis, whereas the Cd-Zn and Cd-Pb-Zn combined stresses significantly reduced the content of Cd in the roots, stems, and leaves. The accumulation of Cd was 0.32 mg· pot^-1 under the single Cd stress. The Cd-Pb stress did not significantly change the accumulation of Cd(0.34 mg·pot^-1), while the Cd-Zn (0.14 mg·pot^-1) and Cd-Pb-Zn(0.13 mg·pot^-1) combined stresses significantly reduced the accumulation. The results of bioaccumulation and translocation factors of Cd in P. yunnanensis under different stress conditions showed that the interaction between Pb and Cd(Pb×Cd) promoted Cd accumulation from the soil and enhanced Cd translocation, showing a synergistic effect. The interaction between Zn and Cd inhibited the accumulation of Cd, but increased the translocation of the absorbed Cd to the shoot, showing an antagonistic and synergistic effect on Cd accumulation and translocation, respectively. The interactions among Pb, Zn, and Cd inhibited both the accumulation and translocation of Cd, showing an antagonistic effect. This study shows that P. yunnanensis seedlings exhibite tolerance to the combined stress of Cd-Pb and Cd-Zn, and that the effects of heavy metal combined stress on Cd accumulation and translocation depend on the type of metal interaction and the specific plant organ.