Antimony uptake and toxicity in sunflower and maize growing in SbIII and SbV contaminated soil

Using pot experiments, we investigated the uptake of antimony (Sb) by sunflower (Helianthus annuus L. cv. Iregi), and maize (Zea mays L. cv. Magister) in two different soils, a potting mix and an agricultural soil. In one treatment Sb was added to the experimental soils as KSb(OH)(6) (Sb-V-treatment) and in the other as Sb2O3 (Sb-III-treatment). Soluble soil Sb concentrations were linearly related to the applied Sb rates, ranging from 0.02 (controls) to 175 mg L-1 soil solution. Accumulation of Sb tended to be slightly higher in the Sb-V treatment in sunflower, while no difference in Sb uptake between the two Sb treatments was found in maize. The half maximal effective concentration (EC50) values derived from the dose-response curves were higher for the Sb-V than for the Sb-III treatment when they were related to soluble soil Sb concentrations, but differences became insignificant when they were related to shoot Sb concentrations. Maize was substantially more sensitive to Sb toxicity than sunflower, indicating physiological differences in Sb tolerance between the two plant species. Our results show that on soils with high Sb contamination, as often found in shooting ranges, plants may suffer from Sb toxicity.