Effects of high arsenic and fluoride soil concentrations on soybean plants.

Arsenic (As) and Fluoride (F) are present in many soils, affecting crops and posing risks in the food chain. We performed pot experiments on spiked soils enriched in these elements either individually or simultaneously, over a wide range of concentrations. Soybean biomass production, grain yield, As and F accumulation and distribution within the plant, and the antioxidant response to these stresses were analyzed. Arsenic was more toxic than F. At As levels >35 mg/kg and F levels >375 mg/kg, yield loss reached 60% and 30%, respectively. At the highest dose of As plants died within 2 weeks, whereas F showed no lethality. When they were applied simultaneously, detrimental effects were more important. As and F in plants increased in all soybean organs although grains presented the lowest concentrations. Antioxidant enzymes were enhanced inplants but this increase was not high enough to cope with the oxidative damage.