Cadmium Concentration in Flax Colonized by Mycorrhizal Fungi Depends on Soil Phosphorus and Cadmium Concentrations

Effect of arbuscular mycorrhizal (AM) fungus on cadmium (Cd) concentration in flax was investigated in a pot experiment. Flax inoculated with Glomus intraradices and uninoculated controls were grown in a pasteurized soil that received Cd (0, 2.5, and 10 mg kg−1) and phosphorus (P; 10 and 50 mg kg−1) additions. Root colonization was not affected by Cd addition but was reduced by high P addition. Effect of G. intraradices on Cd was evident only at low P supply. Inoculation with G. intraradices decreased shoot Cd at no or low Cd addition, which was attributed to reduced root-to-shoot Cd translocation. In contrast, G. intraradices inoculation increased shoot Cd at high Cd addition, which might be associated with the greater absorption of Cd by extraradical hyphae and lower rhizosphere pH. Our results indicate that a benefit of AM fungus in reducing Cd in crops is achievable at Cd and P concentrations commonly in agricultural soils.