Growth response characteristics of alfalfa (Medicago sativa L.) grown in soil artificially contaminated with vanadium and soil naturally rich in vanadium

Abstract

Plant growth responsive characteristics are critical to evaluate the metal resistance of the plant, especially for elements whose essentiality for higher plants have not yet been clearly defined until now. Therefore, an indoor pot experiment was conducted for alfalfa (Medicago sativa L.) grown in clean soil exogenously supplied with artificial source of soluble vanadium [0 (control), 75, 150, 300, 600, 900 mg kg⁻¹] and in the soil naturally rich in vanadium from a mining area (marked as M₀), respectively. Versus control, alfalfa growth was markedly influenced at ≥ 150 mg kg⁻¹ exogenously supplied vanadium and M₀ treatment. The inhibited alfalfa growth at M₀ treatment may incorporate multifactor due to complicated components of the vanadium-rich soil from the mining area. Vanadium translocation capability of the alfalfa at M₀ treatment was significantly higher than that at the exogenous vanadium-addition treatments. The total uptake of vanadium in the alfalfa increased significantly at 75−300 mg kg⁻¹ vanadium treatment, while no apparent difference arose at M₀ treatment versus control. The percentage of root vanadium uptake to the total amount markedly increased and later decreased marginally with vanadium concentration; a converse changing trend of the aboveground parts was noted. In addition, Proteobacteria were the most abundant bacteria community at all treatments excluding 900 mg kg⁻¹ exogenous vanadium treatment. Actinobacteria, Chloroflexi, Gemmatimonadetes, and Acidobacteria were relatively abundant bacterial communities in soil with vanadium addition treatments. Alfalfa exhibited the potential to colonize in the vanadium-rich soil from natural/artificial sources by modulation of its vanadium bioaccumulation and translocation capability.