Enrichment of broccoli seedlings with iron and its impact on germination, antioxidant activity, and the level of phenolic compounds

Biofortification of edible seedlings (sprouts) is a promising strategy to combat dietary nutrient deficiency. In the present study, we made an attempt to enrich broccoli seedlings through imbibition with Fe at two concentrations, 100 mg Fe · dm<sup>–3</sup> and 500 mg Fe · dm<sup>–3</sup>, of four chemical forms: FeCl<sub>2</sub>, FeCl<sub>3</sub>, FeSO<sub>4</sub>, or Fe<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>. The imbibition in all of the solutions resulted in a significant increase in Fe content in the seedlings, wherein it was the highest by the imbibition in sulphates applied at the highest concentration (500 mg·dm<sup>-3</sup>). In addition, the imbibition in sulphates in general did not affect the germination rate, whereas the imbibition in chlorites hampered the germination process. The application of Fe at a concentration of 500 mg Fe · dm<sup>–3</sup> in the form of FeSO<sub>4</sub> enhanced antioxidant activity, while the application of Fe in the form of FeCl<sub>2</sub> and FeCl<sub>3</sub> stimulated the accumulation of anthocyanins. It can be concluded that seed imbibition in Fe in the form of FeSO<sub>4</sub> is an easy and cheap method for biofortification of broccoli seedlings, leading to a nearly 10-fold increase in Fe content and significant enhancement of antioxidant activity, without affecting the germination rate.