Increasing the fungal inoculation of mine tailings from 1 to 2% decreases plant oxidative stress and increases the soil respiration rate

Abstract

There is a knowledge gap about the quantitative aspects of mycorrhizal fungi’s influence on ecological succession on tailings. Here, we demonstrate that inoculating mine tailings with 2% fungi yields significantly better results in terms of plant biomass and lower lipid peroxidation compared to 1% and 0%, both when growing Agrostis capillaris alone and in combination with Melilotus albus. Lipid peroxidation in the A. capillaris is positively predicted by Cu, and negatively predicted by the total Kjeldahl nitrogen in plants. The biomass of M. albus is positively predicted by the N/P ratio, and negatively by Cu concentration in the plant. This improvement was related to differences between the Technosols properties at the end of the experiment (pH, EC, N-NH4+, N-NO3−), which modulated the changes of the tailing material properties from the wet to the dry state, and to differences in the accumulation factors of Cu and Pb from substrate to plant roots, and of the transfer factors from roots to aboveground parts. This is the first time that the effects of such a slight increase in fungal inoculum percentage have been reported. Fine-tuning the fungi treatment can lead to cost-effective techniques for tailings remediation. Block diagrams of an eco-technology are proposed.