Phosphate Amendments Moderate the Arsenate Accumulation and Its Subsequent Oxidative and Physiological Toxicities in Amaranthus viridis L

Arsenic, a carcinogenic metalloid, may enter into food chain through the consumption of crops irrigated with arsenic contaminated underground water. The traditional prevention of the arsenic entry into the food chain in a vast scale of agriculture is very difficult. The only way to prevent this entry is to increase the supply of arsenic analogue phosphate, an essential plant growth nutrient in soil. Two-factor randomized hydroponic experiment (3 arsenate × 5 phosphate concentrations) was performed for 28 days with 11 days old seedlings of Amaranthus viridis L. Concentrations of superoxide dismutase, catalase, peroxidase and malondialdehyde increased up to 2.12, 1.47, 1.86 and 3.66 folds, respectively at concentration of 40 µM arsenate. Addition of phosphate resulted in the decrease in arsenic accumulation by 68.18 %. At 400 µM phosphate amendment, there were also a decrease in the levels of superoxide dismutase, catalase, peroxidase and malondialdehyde up to 21.52, 26.55, 28.44 and 37.15 %, respectively. The toxicity reduction at physiological level was observed as nearly 1.8 fold increase in the contents of both chlorophyll and biomass. The arsenic entry into food chain via plants can thus be prevented by the addition of phosphate into the growth medium.