Beneficial effects of arbuscular mycorrhizae on Cu detoxification in Mimosa pudica L. grown in Cu-polluted soils.

Arbuscular mycorrhizal (AM) fungi are known to have beneficial effects on host plants growing on contaminated soils. The present study aimed at investigating the influence of two different AM fungi (Rhizophagus intraradices and Funneliformis mosseae) on the growth of plants and Cu uptake by Mimosa pudica L. grown in polluted soils containing various levels of Cu (Control, 400, 500, or 600 mg kg-l soil) in pot experiments. Mycorrhizal colonisation rates by the two AM fungi decreased markedly with the increasing Cu levels in soils. This inhibition was more pronounced to F. mosseae than R. intraradices, indicating that R. intraradices was more tolerant to Cu than F. mosseae. Compared with non-mycorrhizal plants, R. intraradices inoculation increased plant growth (including shoot height, numbers of compound leaves and leaflets, and dry biomass) and P concentrations in the shoots and roots of M. pudica at all levels of Cu. Meanwhile, F. mosseae displayed a capability of growth promotion to M. pudica much later and lower than R. intraradices. F. mosseae and R. intraradices markedly decreased Cu concentration in shoots at 400-600 mg kg-1 Cu levels. However, R. intraradices was more efficient than F. mosseae in decreasing the shoot Cu concentrations. As for the increasing Cu tolerance by R. intraradices, possibly it was reached though the improvement of phosphorus nutrition and the decline of Cu transport from roots to shoots of M. pudica. R. intraradices showed a good potential for improving medicinal plants growth and declining toxic effects in Cu-contaminated soils.