An effect of various selenium forms and doses on antioxidant pathways at clover (Trifolium pratense L.)

The aim of this study was to determine the effect of different doses and forms of foliar applied selenium on antioxidant indicators and selenium content in the forage of red clover (Trifolium pratense L.). This was done in the pot experiment, where the plants were placed in chambers under controlled-environment. In the experiment, different forms of selenium (sodium selenite, and/or sodium selenate), in concentrations corresponding to 2, 4 and 20 mg.m(-2) was used. Samples of aboveground tissues were taken at 14th, 28th and 42nd day after foliar application of selenium. The obtained samples were analysed using chromatographic and spectrophotometric techniques. After successful foliar application of selenium, the significant (P < 0.05) increase of the selenium content in aboveground mass of red clover was found. The maximum values for both forms were achieved in experimental groups treated with the highest concentration of selenium (20 mg.m(-2)). In comparison with selenate, selenite showed approximately 50% less efficient accumulation of selenium in the aboveground mass. From the determined antioxidants indicators, a positive effect in particular on the level of reduced glutathione was observed (P < 0.05) in both experimental groups (selenate, and/or selenite). The group treated with selenate had also higher content of phytochelatin 3 (P < 0.05). Despite the use of high selenium concentration (20 mg.m(-2)) its toxic effect on plants was not observe