Shoot Production and Mineral Nutrients of Five Microgreens as Affected by Hydroponic Substrate Type and Post-Emergent Fertilization

Abstract

As a new specialty crop with high market value, microgreens are vegetable or herb seedlings consumed at a young age, 7–21 days after germination. They are known as functional food with high concentrations of mineral nutrients and health beneficial phytochemicals. Microgreen industry lacks standardized recommendations on cultural practices including species/variety selection, substrate choice, and fertilization management. This study evaluated shoot growth and mineral nutrient concentrations in five microgreens including four Brassica and one Raphanus microgreens as affected by four hydroponic pad types and post-emergent fertilization in two experiments in January and February 2020. The five microgreens varied in their shoot height, fresh, dry shoot weights, and mineral nutrient concentrations with radish producing the highest fresh and dry shoot weights. Radish had the highest nitrogen (N) concentration and mustard had the highest phosphorus (P) concentrations when grown with three hydroponic pads except for hemp mat. Hydroponic pad type altered fresh, dry shoot weights, and mineral nutrients in tested microgreens. Microgreens in hemp mat showed the highest shoot height, fresh, dry shoot weights, and potassium (K) concentration, but the lowest N concentration in one or two experiments. One time post-emergent fertilization generally increased shoot height, fresh, dry shoot weights, and macronutrient concentrations in microgreens.