Abstract: Maize (Zea mays L.) was inoculated with or without VA-mycorrhizal (Glomus mosseae) and cultivated in a heavy metals contaminated soil. The distribution and dynamics of Cu,Zn,Pb and Cd forms in rhizosphere of maize inoculated with or without VA-mycorrhizal were analyzed with the technique of sequential extraction. Comparing with control soil, exchangeable Cu in rhizospheric soil increased significantly, and the exchangeable Cd trended down. In rhizosphere of VA-mycorrhizal maize, the amounts of Cu, Zn and Pb bound to organic matter were significantly higher than those in rhizosphere of non-mycorrhizal maize, while the four tested metals bound to carbonates and to iron and manganese oxides were constant in rhizosphere of mycorrhizal and non-mycorrhizal maize. These results illustrated that the plant roots could influence the distribution and dynamics of metal forms in rhizosphere, and much for mycorrhizal plants than for non-mycorrhizal plants. At excessive concentration of soil metals, mycorrhizal roots might decrease the bio availability of toxic heavy metals by changing their forms. The factors that caused the change of metal fractions in rhizosphere of mycorrhizal and non-mycorrhizal plants were also discussed.

Key words: VA-mycorrhiza, Rhizosphere, Heavy metal, Metal form