Selenium uptake in Zea mays supplied with selenate or selenite under hydroponic conditions
Résumé
Selenium is an essential micro-nutrient for animals, humans and microorganisms; it mainly enters food chains through plants. This study proposes to explore effect of inorganic Se forms on its uptake and accumulation in Zea mays. Zea mays was grown in a controlled-atmosphere chamber for 2 weeks in a hydroponic solution of low-concentration selenium (10 mu g/L (i.e.0.12 mu M) or 50 mu g/L (i.e. 0.63 mu M) of Se). For each concentration, four treatments were defined: control (without selenium), selenite alone, selenate alone and selenite and selenate mixed. At low concentrations, selenium did not affect the biomass production of Zea mays. However, for both concentrations, Se accumulation following a selenite-only treatment was always higher than with selenate-only. Moreover, in the selenate-only treatment, Se mainly accumulated in shoots whereas in the selenite-only treatment, Se was stocked more in the roots. Interactions between selenate and selenite were observed only at the higher concentration (0.63 mu M of selenium in the nutrient solution). Se form and concentration in the nutrient solution strongly influenced the absorption, allocation and metabolism of Se in Zea mays. Selenate seems to inhibit selenite absorption by the roots.