Mining and metallurgy activities practiced in the Comarca Lagunera in Mexico have contaminated soil, air and water. The use of plants is one strategy for the remediation of soils contaminated with heavy metals. However, few studies on remediation with plants of arid and semiardid zones in association with mycorrhizae have been performed. The aim of this study was to evaluate the ability of pigweed (Amaranthus hybridus L.) to extract Pb and Cd by adding a mixture of arbuscular mycorrhizae (Entrophospora columbiana, Glomus intraradices, G. etunicatum, G. clarum) to the substrate contaminated with Pb or Cd. Two experiments, one for each metal, under the basis of an experimental design with randomized blocks with four replications were carried out. The first experiment considered three doses of mycorrhizae (0, 2.5 and 5.0 g·kg-1) added to the soil contaminated with 300 mg·kg-1 Pb. In the second experiment, we used the same quantities of mycorrhizae added to soil contaminated with 15 mg·kg-1 Cd. The concentration of Pb and Cd in root, leaf and stem at 65, 95 and 125 days of age of the plant were determined with an atomic absorption spectrophotometer. The results indicate that the addition of mycorrhizae significantly increased the concentration of Pb and Cd in root, stem and leaf. The concentrations of Pb and Cd were increased significantly as the age of the plant increases.

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