The biofortification of leafy vegetables with selenium (Se) and iodine (I) provides the basis for the Se/I status optimization and preservation of human health. The effect of foliar Se, I, and Se + I supply in three different crop cycles (autumn, autumn–winter, and winter) on yield, quality, and mineral composition of wall rocket leaves was investigated using biochemical and ICP-MS methods of analysis. Joint foliar supply with selenate/iodide increased yield, antioxidant activity, total phenolic, ascorbic acid, and protein levels by 1.63, 1.24, 1.22, 1.25, and 1.50 times, respectively, and the content of Ca, Mg, P, K, Fe, Cu, and Zn by 1.27, 1.24, 1.35, 1.46, 3.67, 2.76, and 1.44 times, respectively. High correlations between Se, antioxidants, P, Mg, and Ca (r > 0.80) as well as between yield and K/protein content were recorded. Despite a significant decrease in yield, protein, and K, Fe, Cu, and Mn contents in the third crop cycle, compared to the first one, 50 g of wall rocket biofortified with Se/I may provide up to 100% of the Se adequate consumption level, 34.3% of I, 9% of K, 24% of Fe, and 17.7% Ca. The results of the present research confirm the high efficiency of Se/I supply to produce D. tenuifolia leaves as a new functional food.
