Potential of Leersia hexandra Swartz for phytoextraction of Cr from soil.

Research on the phytoextraction of Cr from contaminated soils has been scarce, because very few plant species have been reported to accumulate Cr to high concentrations in their aerial parts. In this study, a Cr-hyperaccumulator, Leersia hexandra was investigated for its potential to remove Cr from the soil in a series of pot experiments. The results showed that L. hexandra had a high extraction capacity for chromium in soil, with the highest Cr concentration in shoot of 1844 mg/kg. Model calculation based on the negative linear relationship between the bioconcentration factors (BCF) and the concentrations of soil Cr indicated that phytoremediation using L. hexandra was feasible when soil was only moderately contaminated with Cr. Three sequential harvests did not significantly alter Cr accumulation and shoot biomass (p > 0.05), indicating that sequential harvest might be an available and convenient way to achieve the decontamination of Cr-contaminated soils by L. hexandra. On average, fertilization increased the shoot biomass by 45% and the total amount of extracted-Cr by 26%, suggesting that fertilization is able to enhance Cr phytoextraction of L. hexandra. Although EDTA increased the concentrations of Cr in shoots by 1.4 times, it also resulted in low plant biomass, thereby decreasing the amount of Cr accumulation.