Selenium uptake and species distribution in selenium-enriched bean (Phaseolus vulgaris L.) seeds obtained by two different cultivations

In this work, bean plants were cultivated in two different ways using two modes of selenium supplementation in the form of sodium selenate. Each group consisted of the same four cultivars. Group A plants were grown in soil and twice foliarly sprayed at an interval of 10 days with an aqueous solution of 10 mg Se L-1 stop at flowering time. Group B plants were hydroponically cultivated after the maternal seeds were soaked in nutrient solution containing the same Se content as used for foliar fertilisation. Bean seeds obtained from group A plants accumulated much more Se (around 2 mu g g(-1) stop dry weight) than those seeds obtained from group B plants (around 0.6 mu g g(-1) stop dry weight). No differences in Se content within each group were found. After enzyme hydrolysis, 85 +/- 7% of soluble selenium was found in group A and 65 +/- 2% of soluble Se in group B with respect to the total Se content in seeds. In bean seed supernatants SeMeSeCys, SeMet and two unknown species were found. These four species together represented 79 +/- 8 and 53 +/- 9% of the Se mass fraction of group A and group B, respectively. No differences in the presence of selenium species were found between the four cultivars and cultivation conditions.