Phosphorus Enhances Cr(VI) Uptake and Accumulation in Leersia hexandra Swartz.

The effects of P supplementation on chromium(VI) uptake by Leersia hexandra Swartz were studied using pot-culture experiment. P-deficiency and zero-P addition controls were included. The Cr(VI) uptake followed Michaelis-Menten kinetics. Compare with the control, the P-supply decreased the Michaelis constant (Km) by 16.9% and the P-deficiency decreased the maximum uptake velocity (Vmax ) by 18%, which indicated no inhibition and competition between P and Cr(VI) uptake by L. hexandra. Moreover, there were a synergistic action between P and Cr(VI) suggests that Cr(VI) uptake by the roots of L. hexandra may be an active process. The bioconcentration factor (BCF) and the transport factor (TF') increased with the increase in P supply. The highest BCF was 3.6-folds higher than the control, indicating that the additional P contribute to a higher ability of L. hexandra transporting Cr from root to the aboveground parts.