ACCUMULATION OF SELENIUM IN PLANTS GROWN ON SELENIUM-TREATED SOIL

High concentrations of Se found in the environment may be detrimental to sustainable agriculture in parts of the western USA. Greenhouse pot experiments were conducted to study Se concentrations in different plant species grown in soil with added Se. Astragalus incanus L. (no common name), creeping saltbush (Atriplex semibaccata R. Br. L.), Old Man saltbush (Atriplex nummularia Lindl L.), wild brown mustard (Brassica juncea Czern L.), and tall fescue grass (Festuca arundinacea Schreb L.) were grown in potting soil to which 3.5 mg Se6+ or Se4+ kg-1 was added either as Na2SeO4 or Na2SeO3, respectively. During the growing season, plants from both Se-treated soils were clipped either once, twice, or three times. After 50 to 55 d in Se-treated soil, plants were harvested, separated into shoots and roots, and analyzed for total tissue Se. Soils from each species were analyzed for total residual Se. Each species grown in Se6+-treated soils, accumulated significantly (P < 0.001) more Se than plants grown in Se4+-treated soil. For both Se6+ and Se4+ treatments, wild brown mustard and A. incanus had the highest and lowest tissue Se concentrations, respectively. Clipping of plants significantly (P < 0.05) increased the accumulation of Se in the total harvested shoot tissue for wild brown mustard and slightly for the other species tested (except Old Man saltbush). Reduction in soil Se was observed for each species, with the greatest reduction occurring when plants of wild brown mustard were grown and clipped. Within any given treatment, wild brown mustard accumulated the highest concentrations of Se. In the remaining species, Se accumulated in the following order: Old Man saltbush > creeping saltbush > tall fescue > A. incanus. Selenium removal from soil by each species generally followed the same order as the accumulation of Se in the plant.