Bedeutung der arbuskulären Mykorrhiza (AM) für die Schwermetalltoleranz von Luzerne (Medicago Sativa L.) und Hafer (Avena sativa L.) auf einem klärschlammgedüngten Boden

Effect of arbuscular mycorrhizal fungi (AMF) on heavy metal tolerance of alfalfa (Medicago sativa L.) and oat (Avena sativa L.) on a sewage-sludge treated soil In pot experiments with a sewage sludge treated soil, the influence of two arbuscular mycorrhizal fungi (AMF) isolates of Glomus sp. (T6 and D13) on plant growth and on the uptake of heavy metals by alfalfa (Medicago sativa L.) and oat (Avena sativa L.) was investigated. Alfalfa showed an increase of biomass with mycorrhizal infection only to a small extent. In oat AMF inoculation increased the growth of both root and shoot by up to 70% and 55% respectively. Mycorrhization raised the P-content and -uptake in alfalfa, but not in oat, in both roots and shoots. Mycorrhizal alfalfa showed lower Zn-, Cd- and Ni-contents and uptake in roots and shoots. The root length was significantly decreased in mycorrhizal alfalfa plants (up to 38%). The translocation of heavy metals into the shoot of mycorrhizal alfalfa was slightly increased. Mycorrhizal infection of oat led to higher concentrations of Zn, Cd and Ni in the root but to less Zn in the shoot. The translocation of heavy metals to the oat shoot was clearely decreased by mycorrhizal colonisation. This may be based on the ability of fungal tissues to complex heavy metals at the cell walls, thus excluding metals from the shoot. This conclusion is supported by the enhanced root length (up to 78%) of mycorrhizal oat plants in this experiment. The mycorrhizal infection seemed to protect plants against heavy metal pollution in soils. It was obvious that different host plants reacted in different ways.