Interactions between accumulation of trace elements and macronutrients in Salix caprea after inoculation with rhizosphere microorganisms

Although the beneficial effects on growth and trace element accumulation in Salix spp. inoculated with microbes are well known, little information is available on the interactions among trace elements and macronutrients. The main purpose of this study was to assess the effect of phytoaugmentation with the rhizobacteria Agromyces sp., Streptomyces sp., and the combination of each of them with the fungus Cadophora finlandica on biomass production and the accumulation of selected trace elements (Zn, Cd, Fe) and macronutrients (Ca, K, P and Mg) in Salix caprea grown on a moderately polluted soil. Dry matter production was significantly enhanced only upon inoculation with Agromyces sp. Regarding the phytoextraction of Cd and Zn, shoot concentrations were mostly increased after inoculation with Streptomyces sp. and Agromyces sp. + C. finlandica. These two treatments also showed higher translocation factors from roots to the leaves for both Cd and Zn. The accumulation of Cd and Zn in shoots was related to increased concentrations of K. This suggests that microorganisms that contribute to enhanced phytoextraction of Cd and Zn affect also the solubility and thus phytoavailability of K. This study suggests that the phytoextraction of Zn and Cd can be improved by inoculation with selected microbial strains.

► In this study we assess the effect of different rhizosphere microbes on the phytoextraction efficiency of Salix caprea.
► The different inocula have significantly influenced the root biomass and the accumulation of zinc, cadmium, and potassium.
► Higher concentrations of Zn and Cd in leaves were associated with increased accumulation of K.
► Rhizosphere microbes may enhance the phytoextraction capacity also on moderately polluted soils.