Accumulation of chromium by Commelina communis L. grown in solution with different concentrations of Cr and L-histidine

Abstract

Hydroponic experiments conducted to examine the chromiun uptake by C. communis in the presence of different Cr concentrations (Cr⁶⁺ 100 and 200 mg/L, respectively) and free histidine supplementation (0.5 and 1.0 mol/L) showed that shoot and root growth of C. communis decreased greatly with increasing Cr concentrations in the medium; and that the species was a typical excluder since it accumulated high concentrations of Cr in roots but comparatively low concentrations in shoots. Chromium in shoots and roots of Cr₄²⁻-supplied plants ranged from 329–1880 and 3788–4240 mg/kg DW, respectively, while those of Cr₄²⁻-histidine-supplied plants ranged from 478 to 629 mg/kg and 4157–4303 mg/kg DW, respectively. With Cr present in the hydroponic solution, C. communis accumulated more Cr in its tissues. Increasing histidine application to the solution significantly increased chromium accumulation in the plant tissues but could not alter the accumulation pattern of plants although it induced a higher concentration of Cr in its shoots and roots. These features suggested that C. communis may serve as an alternative species in a constructed wetland for phytoextraction treatment of Cr-containing wastewater and for phytostabilization of Cr mining spoils.