AM菌对三叶草吸收、累积重金属的影响

Effects of arbuscular mycorrhizal fungi on heavy metal tolerance of clover in contaminated soil

  • 摘要: 采用4室根箱培养系统,探讨了Cu、Zn、Pb、Cd 4种重金属复合污染土壤中,丛枝菌根菌对三叶草生长及吸收、累积重金属的作用,结果表明:重金属Cu 100mg/kg、Zn 600mg/kg、Pb 300mg/kg、Cd 10mg/kg的复合污染对三叶草生物量影响较小,但土壤重金属处理使丛枝菌根菌Glomus intraradices和Glomus caledonium对三叶草的侵染率分别降低53%和56%,菌种G.intraradice的菌丝密度降低73%;接种菌根真菌能明显减少重金属复合污染土壤中三叶草对Cu、Cd和Pb的吸收,并强化根系在限制重金属Pb和Cd向地上部运输中的作用,地上部Pb和Cd含量分别下降24.2%~55.3%和65%~97.9%,使三叶草地上部Cd和Pb含量均低于我国牧草重金属安全含量,提高了三叶草可食部分的质量;不同菌根真菌对三叶草吸收、累积及分配重金属的影响有明显差异,Glomus intraradices对减少三叶草对重金属的吸收及其在地上部可食部分的累积的作用大于Glomus caledonium。丛枝菌根菌对于强化三叶草根系对重金属的固持作用,调节生态系统中重金属的生物循环,减轻重金属对食物链的污染风险方面起着重要作用。

     

    Abstract: The effects of arbuscular mycorrhizal fungi (AMF) on Cu,Zn,Pb and Cd uptake and distribution in red clover plant were investigated by using a four-compartment culturing system under greenhouse conditions. Cu(CuSO4·5H2O)100mg/kg,Zn(ZnSO4·7H2O)600mg/kg,Pb[Pb(NO3)2]300mg/kg,Cd(CdSO4·8H2O)10mg/kg were added to loamy soil which was precultured for one month before sowing clover seeds. The growth of red clover is observed not to be impeded in the heavy metal contaminated soil,while inoculation rates of two AMF species Glomus intraradices and Glomus caledonium are significantly decreased by 53% and 56% respectively and hypla density of Glomus intraradices is decreased by 73%. AMF still significantly decreases the uptake of Cu,Cd and Pb,and prevents transportation and distribution of heavy metals in the shoot systems of the clover plants. The concentrations of Pb,Cd in the clover shoots decrease by 24.2%~55.3% and 65%~97.9% respectively,compared with non-inoculated clover,below the upper limits of the standards of animal feed in China. It is concluded that AMF can increase clover quality and benefit field treatment of sewage one the hand,and limit contaminants uptake through food chain on the other. AMF plays a crucial role in regulating Cu,Zn and,especially Pb,and Cd bio-recycling in the ecosystem and in alleviating the stress and transfer of heavy metals along food chain.

     

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