Combining microgreens cultivation and biostimulant application in hydroponic systems accentuate yield and visual quality of functional food

Health-boosting vegetables characterized with gastronomic pleasure is exactly the quest of modern times due to the benefits that humans can assume from the phytochemicals present in plants. Vegetables are rich in biologically active specialized metabolites. Microgreens are an example of such functional food with vivid colors and intense flavors. In addition, it has a short cultivation cycle, which suits indoor farming as well as vertical farming and is characterized by a minor footprint regarding water, and fertilizers. Microgreens could even thrive better with the modulation of some pre-harvest factors like light spectrum/intensity and the application of biostimulants in the nutrient solution. Biostimulants such as protein hydrolysates are rich in free amino acids and small peptides that could boost microgreens yield even during short growing cycles. Therefore, vegetal protein hydrolysates were applied at 0.3 mL L-1 in a quarter-strength modified Hoagland nutrient solution to grow Lepidium sativum L. and Brassica oleracea L. var. gongylodes in a floating raft system. The application of biostimulants proved beneficial but genotype dependent, since the yield increased in different proportions among the two tested microgreens species, yet beneficial for both. In addition, all color attributes of both species were modulated under protein hydrolysates application, except for Hue (°) that was only dominated by the genetic factor. The combination of biostimulants and floating system prove to be promising for indoor farming by increasing yield and qualitative visual aspects of the microgreens cultivated.