Yield performance, mineral profile, and nitrate content in a selection of seventeen microgreens species

Authors: DI GIOIA, FRANCESCO - Pennsylvania State University; Hong, Jason; Pisani, Cristina; PETROPOULOS, SPYRIDON - University Of Thessaly; Bai, Jinhe; Rosskopf, Erin

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2023
Publication Date: 7/20/2023
Citation: Di Gioia, F., Hong, J.C., Pisani, C., Petropoulos, S., Bai, J., Rosskopf, E.N. 2023. Yield performance, mineral profile, and nitrate content in a selection of seventeen microgreens species. Frontiers in Plant Science. 14 : Article 1220691. https://doi.org/10.3389/fpls.2023.1220691.
DOI: https://doi.org/10.3389/fpls.2023.1220691

Interpretive Summary: Interest in the production and consumption of microgreens has been growing rapidly. Microgreens are considered an excellent source of minerals but little is known about their inherent mineral content. A controlled study was conducted to determine the mineral content of seventeen microgreen species belonging to 7 different plant families. Each microgreen species was grown on a natural fiber mat and after germination, they were fertigated with a weak nutrient solution containing no microelements. At harvest (10 to 19 days after sowing based on the species), yield components were measured and dry tissue samples were analyzed for the concentration of total nitrogen (N), nitrate (NO3-), phosphorous (P,) potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), and boron (B). There were significant differences between microgreen species for the accumulation of both macro and microelements, as well as yield. Several species could be used to meet the recommended daily requirements for minerals and for Fe and Zn, agronomic fortification may be needed. Microgreens can be a good source of minerals and their yield potential and mineral profiles are largely determined by the genotype. By using specific selections, it is possible to address different dietary needs.

Technical Abstract: Originally regarded as garnish greens, microgreens are increasingly valued for their nutritional profile, including their mineral content. A study was conducted under controlled environmental conditions utilizing a selection of seventeen commonly grown microgreen species belonging to seven different botanical families to investigate the genetic variation of macro- and micro-minerals and nitrate content. Microgreens were grown in a soilless system using a natural fiber mat as the substrate. After germination, microgreens were fertigated with a modified half-strength Hoagland solution prepared using deionized water and without microelements. At harvest (10 to 19 days after sowing based on the species), yield components were measured and dry tissue samples were analyzed for the concentration of total nitrogen (N), nitrate (NO3-), phosphorous (P,) potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), sodium (Na), iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), and boron (B). Genotypic variations were observed for all of the examined parameters. Nitrogen and K were the principal macronutrients accounting for 38.4% and 33.8% of the total macroelement concentration, respectively, followed in order by Ca, P, S, and Mg. Except for sunflower, all the other microgreen species accumulated high (1,000-2,500 mg kg-1 FW) or very high (>2,500 mg kg-1 FW) NO3- levels. Eight of the species tested had a K concentration above 300 mg 100 g-1 FW and could be considered as a good source of K. Scallion, red cabbage, amaranth, and Genovese basil microgreens were a good source of Ca. Among microminerals, the most abundant was Fe followed by Zn, Mn, B, and Cu. Sunflower, scallion, and shiso were a good source of Cu. Except for sunflower, which was a good source of Zn, none of the species examined could be considered a good source of Fe and Zn, suggesting that supplementary fertilization may be required to increase the concentrations of essential microminerals. In conclusion, microgreens can be a good source of minerals, their yield potential and mineral profile are largely determined by the genotype, and by using specific selections, it is possible to address different dietary needs.