Barbara Hawrylak, Maria Szymańska

Abstract. In order to study physiological role of selenium in higher plants, maize was cultivated in a water culture without selenium or amended with selenite or selenate, in concentrations of 25 or 50 μmol·m^-3. Selenium at 25 μmol·m^-3 in selenate form acted as an antioxidant and promoted roots growth. However, at concentration 50 μmol·m^-3 of selenate and at all concentrations of selenite, it was a prooxidant, caused lipid bilayer damage by lipid peroxidation.

Selenium is an essential element for antioxidation reactions in humans, animals and bacteria. In higher plants, however, the role of selenium is still unclear. The objective of this experiment was to investigate the effect of exogenous selenium in its selenite or selenate form on the growth, glutathione concentration and lipid peroxidation in roots of maize seedlings. At low concentration (25 μmol·dm^-3), selenate tended to stimulate the root elongation, the accumulation of glutathione and it acted as an antioxidant, inhibiting lipid peroxidation. At higher concentration of selenate (50 μmol·dm^-3) and at all concentrations of selenite (25 and 50 μmol·dm^-3), selenium was a prooxidant. The accumulation of lipid peroxidation products was enhanced and glutathione concentration increased. Root elongation did not change in presence of 25 and 50 μmol·dm^-3 selenite and selenate, respectively. However, selenite at dosage of 50 μmol·dm^-3 exerted disturbance in root growth and morphology.