Selenium accumulation in selected vegetables

Abstract

Absract Greenhouse experiments were conducted to determine selenium (Se) uptake by sulfur‐accumulating vegetables. Cabbage (Brassica oleracea var. capitata), broccoli (Brassica oleracea var. botrytis), Swiss chard (Beta vulgaris var. cicla) and collards (Brassica Oleracea var. acephda) were grown in a soil mix to which 4.5 mg of selenate or selenite had been added per kg of soil. Plants were grown to maturity, separated into plant organs, and the tissues analyzed for Se and sulfate (SO4). Vegetables grown in selenate laden soil significantly (P<0.05) accumulated higher concentrations of Se than plants grown in selenite laden soil. The highest concentrations of Se and SO4 were found in the broccoli floret and vegetable leaf tissues. A second greenhouse experiment examined the uptake of Se and SO4 in broccoli (Brassica oleracea var. botrytis) grown hydroponically with increasing Se concentrations. Treatments consisted of three Se concentrations (2, 6, and 15 mg of selenate, added as Na2SeO4/L to a synthetic water solution, including SO4). Solution samples were taken weekly and analyzed for Se and SO4. The removal or uptake of both Se and SO4 by broccoli was positively related (P<0.05) with time at each Se concentration. After 6 weeks in Se treatments, uptake responses of Se and SO4 were significantly different (P<0.05) based apon analyses of covariance. Composite leave samples were also taken from the broccoli plants and analyzed for Se and SO4. Selenium concentrations were negatively correlated (P<0.08) with SO4 concentrations in the leaf tissue.