Potential Role of Mycorrhizae Combined with Pinus tabuliformis and Lespedeza bicolor in Repairing Soil Contaminated by Lanthanum and Cerium

Abstract

In order to repair light rare earth soil effectively, plant and mycorrhizae technology were applied together. It will provide theoretical basis for ecological restoration of light rare earth contaminated soil. The method of greenhouse pot experiment was used in this study. The concentrations of lanthanum (La) in tested soil samples were 107.15, 329.41, and 2,031.71 mg/kg and cerium (Ce) were 362.11, 741.81, 4,162.03 mg/kg. The ectomycorrhiza [Inocybe lilacina (IL)] was inoculated on Pinus tabuliformis. The endomycorrhiza [Rhizophagus intraradices (RI), Funneliformis mosseae (FM), and Glomus versiforme (GV)] were inoculated on Lespedeza bicolor. The inoculation rate and biomass of mycorrhiza, as well as the absorption, transfer and root retention of La and Ce, light rare earth elements (LREE) by plants were determined to provide the theoretical basis for the treatment of La and Ce contaminated soil. The results showed that a symbiotic relationship was established between IL and P. tabuliformis, as well as between RI, FM, GV and L. bicolor. The biomass results showed that the dry weight of the above-ground organs and the roots of P. tabuliformis increased, as well as in L. bicolor. With the increase of the concentration of La and Ce in the soil, the increase of one LREE in the host plants inoculated with mycorrhizae was greater than that in the blank control group. Following mycorrhizal inoculation, La and Ce transfer coefficients in P. tabuliformis and L. bicolor decreased, and root retention coefficients increased, which may lead to the decrease of absorption and transfer capacity of hyperaccumulators. This study showed that mycorrhizae can improve the absorption of La and Ce by host plants, demonstrating potential value in the environmental remediation of LREE contaminated soil.