Combined biofortification of carrot with iodine and selenium.

The aim of a three-year study was to assess the effect of combined biofortification with I and Se in carrot. Four cultivars ('Askona' F1, 'Samba' F1, 'Kazan' F1 and 'White Satin') were grown in soil fertilized with KI (4 kg I ha-1) and Na2SeO4 (0.25 kg Se ha-1). The I + Se fertilization did not affect yield but the plants of all cultivars accumulated both elements in leaves and roots. On average, the I and Se contents in roots increased 7.7-times for I and 4.9-times for Se as well as the average I:Se molar ratio was 0.28:1. The contents of both elements in roots remained well below the hazard threshold thus the intake of 100 g of biofortified carrot would substantially cover the RDA for I and Se. The changes in chemical composition of roots (nitrates, phenolic compounds, sugars, carotenoids, macro-, microelements and cadmium) were rather year-dependent than affected by the applied I + Se fertilization.