Hydroponic Production of Selenium-Enriched Baby Leaves of Swiss Chard (Beta vulgaris var. cicla) and Its Wild Ancestor Sea Beet (Beta vulgaris ssp. maritima)

The human intake of selenium (Se), which is an essential element in animals and humans, can be increased through the consumption of vegetables that have been biofortified during cultivation. There is increasing interest in wild edible plants (WEPs) due to their positive effects on health. In fact, many WEPs are rich in microelements, vitamins, dietary fibers, and several antioxidant compounds. Among WEPs, sea beet (Beta vulgaris ssp. maritima) is the wild ancestor of Swiss chard (Beta vulgaris var. cicla). The present study investigated the potential of fortifying Swiss chard and sea beet with Se. The two subspecies were cultivated in a floating system with a nutrient solution enriched with four concentrations of Se (0, 1, 3, and 5 mg L−1), and the production and quality of the baby leaves were evaluated. The addition of Se to the nutrient solution resulted in a higher leaf concentration of this microelement in both subspecies, with a positive effect on the yield (+20%) and leaf chlorophyll concentration (+25%) at the Se concentration of 1 mg L−1. The leaf concentration of nitrates was reduced by the Se treatment in sea beet regardless of the Se concentration (−24%, on average). Selenium biofortification was more effective in sea beet plants than in Swiss chard due to the higher ability of the wild species to acquire readily available minerals from the hydroponic nutrient solution. In conclusion, both subspecies accumulated a significant amount of Se without negative effects on yield or leaf quality, thus proving them to be suitable for the production of Se-enriched baby leaves.