Hydroponic Fiber Mats Altered Shoot Growth and Mineral Nutrient Composition of Five Herbal Microgreens

Microgreens are nutrient-dense foods rich in mineral nutrients and health-benefiting phytochemicals. They are a popular specialty crop with a rapidly increasing industry in the United States (U.S.A.) and worldwide. However, there is a lack of research-based recommendations regarding the feasibility of using hydroponic fiber mats in the production of herbal microgreens and their effects on yield, quality, and nutritional composition. This study assessed shoot development, yield, visual quality, and mineral composition of five herbal microgreen species, including basil, chives, dill, leek, and parsley when grown with four types of hydroponic fiber mats (BioStrate, hemp, jute, and MicroMat) and affected by a single post-emergent fertigation in two experiments. The five microgreens varied in yield, quality, mineral nutrient composition, and their response to substrate type. Chives microgreens produced the highest fresh and dry shoot weights among species when grown with BioStrate, jute, and MicroMat in both experiments. The four substrate types resulted in similar fresh and dry shoot weights in leek and parsley microgreens in both experiments. However, BioStrate and MicroMat increased fresh and dry shoot weights in chives in December compared with hemp or jute mats. Jute resulted in higher fresh and dry shoot weights in basil in both experiments compared with MicroMat. The fiber mats altered mineral nutrient concentrations in tested microgreen species. Hemp mats increased potassium concentrations in basil and dill, while jute mats produced the highest Fe concentrations in the two species and the highest Mn concentration in basil in both experiments. A single post-emergent fertigation increased shoot height and increased concentrations of nitrogen, phosphorus, potassium, sulfur, iron, zinc, manganese, and boron in one or both experiments.