Abstract
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.
Highlights
Selenium (Se) is a trace element and an essential microelement for humans, animals and microorganisms [1], whereas this has not been recognized for plants [2]
In the first and fourth trials, the potential photochemical efficiency of PS II was significantly decreased in L. minor grown in media with selenite and selenate at 2 and 5 mg Se L−1, compared to the control
Treatment of L. minor plants at any concentrations of sodium selenite or sodium selenate and the combination of selenite and selenate induced a worse physiological state and lower concentrations of photosynthetic pigments compared to the control, which indicated that the plants were exposed to stress conditions even at the lowest concentrations of selenite and selenate in the growth media
Summary
Selenium (Se) is a trace element and an essential microelement for humans, animals and microorganisms [1], whereas this has not been recognized for plants [2]. Se can have positive or negative effects on plant growth, depending on its concentrations and chemical forms, and on the plant physiological and phenological phases [3]. The negative effects of Se can be reflected in decreased growth and development, and early senescence of plants [9]. Pollution of soils and waters by various trace elements has resulted in severe environmental problems, with potential consequences on agriculture and human health. Some of these elements are essential micronutrients that are needed for the correct functioning of metabolism and the essential structural and catalytic components of proteins and enzymes, and as cofactors necessary for normal growth and development [10]
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