INFLUENCE OF VA-MYCORRHIZA ON HEAVY-METAL UPTAKE OF OAT (AVENA-SATIVA L) FROM SOILS DIFFERING IN HEAVY-METAL CONTAMINATION

The heavy metal uptake of mycorrhizal oat plants (Avena sativa L.) was evaluated in pot experiments with two soils differing in heavy metal accumulation. The effect of the fungal isolates on the uptake of the immobile metals Zn and Cu differed between the two soils: In the soil ''Kleinlinden'' mycorrhizal colonization increased heavy metal uptake by up to 37%. In the highly contaminated soil ''Munchen'', mycorrhizal infection lead to a higher uptake (max. 59%) in roots but to a reduced translocation to the aerial plant fractions. The higher uptake of Zn and Cu into the roots was related to the higher heavy metal concentrations in this soil. The Cd uptake showed no difference between the two soils, but was increased in the roots by VAM together with a lower translocation into the shoots. VAM-formation changed the root architecture by increasing the specific root length (m g(-1) root dry matter) and the total root length (km per pot). This increased absorbing surface of the roots was a major, but not the only cause for the differences in heavy metal uptake.