Duckweed (Lemna minor L.) Successfully Accumulates Selenium from Selenium-Impacted Water

The absorption of selenium (Se) from water by Lemna minor L. and the influence of different concentrations and forms of Se on its biochemical and morphological characteristics were studied. Plants were exposed to various concentrations of Se: 1 mg Se L−1, 2 mg Se L−1 and 5 mg Se L−1 in sodium selenite and sodium selenate solutions and in a combination of selenite (2 mg Se L−1) and selenate (2 mg Se L−1). When the Se was added in the form of selenate, plants accumulated higher amounts of Se compared to plants exposed to selenite. Comparisons of the combined addition of selenite and selenate (2 + 2 mg Se L−1) with their individual applications (2 and 5 mg Se L−1) showed that for the combination, the L. minor fronds accumulated more Se than in selenite alone. Plants exposed to any of the concentrations of sodium selenate or sodium selenite, or the combination of selenite and selenate, showed inferior physiological performances, and lower concentrations of photosynthetic pigments, compared to control plants. Consequently, growth was also suppressed under the stress conditions caused by higher concentrations of Se in any form. The efficient absorption of Se from the water by L. minor indicates the potential use of this species in phytoremediation processes for waters polluted with Se.