The content of polyphenols and chosen heavy metals in faba bean (Faba vulgaris Moench) relating to different doses of zinc application

We investigated the impact of zinc on chosen heavy metals contents (Cu, Zn, Co, Cd, Pb, Cr, Ni) and polyphenols content and antioxidant capacity of chosen legume. Used soil was from Cakajovce locality (located in Nitra upland) with the neutral soil reaction suitable for the legume cultivation. Determined Cd content as well as Pb content in the soil was on the level of critical value given for the relationship between soil and plant. The values of both elements were far below threshold values proposed by European Commission. In experiment we used two cultivars of fababean - Saturn, Zobor. Seeds of fababean were harvested in milk ripeness. The different high doses of zinc (as ZnSO4.7H2O) were applied into the uncontaminated soil in model conditions. The strong statistical relationship between added Zn content in the soil and in seeds of both faba bean cultivars as well as was the total polyphenols content and the total antioxidant capacity values was confirmed. In all variants the determined Zn amount was below (Saturn) or slightly above (Zobor) the hygienic limit given by the legislative. On the other hand faba bean of both cultivars accumulated high amounts of Pb and Cd - in all variants higher than hygienic limits. The contents of all other heavy metals (Ni, Co, Cr, Cu) were lower than hygienic limits. The polyphenols content ranged from 2208 to 4622 milligrams per kilogram of fresh sample calculated as gallic acid equivalents. Faba bean shows a very small antioxidant capacity - 4.66 - 5.71% of DPPH inhibition