Shoot Yield and Mineral Nutrient Concentrations of Six Microgreens in the Brassicaceae Family Affected by Fertigation Rate

Abstract

Microgreens have become an important specialty crop valued by their varying texture, vibrant colors, and nutrient-dense features. As the number of species and cultivars rapidly increases for microgreen production, fertigation requirements in relation to shoot production and nutrient compositions remain unclear. This study aimed to investigate the shoot yield, visual quality, and mineral nutrient concentrations of six microgreens in the Brassicaceae family including the ‘Waltham’ broccoli, ‘Red Acre’ cabbage, Daikon radish, ‘Red Russian’ kale, pea, and Rambo radish in two experiments in December 2020 and January 2021. Each microgreen was fertigated with 120 mL of fertilizer solution daily for five consecutive days with a rate of 0, 70, 140, 210, or 280 mg·L−1 N from a general-purpose fertilizer. Broccoli, Daikon radish, and kale similarly produced the highest fresh shoot weights of 916.5 to 984 g·m−2 in December 2020, while pea produced the highest fresh shoot weight of 2471 g·m−2 in January 2021 among cultivars. The fertigation rates of 140, 210, and 280 mg·L−1 N resulted in similar fresh and dry shoot weights of selected microgreens, suggesting 140 mg·L−1 N should be sufficient for microgreen fertilization. Mineral nutrients in microgreens varied among cultivars: pea microgreens had the highest nitrogen (N) concentrations of 70.6 to 75.2 mg·g−1 in December 2020 and 72.1 to 75.4 mg·g−1 in January 2021; and cabbage microgreens were rich in calcium (Ca) in both experiments. The kale, pea, and Rambo radish microgreens contained the highest concentrations of iron (Fe) and manganese (Mn) in December 2020. The fertigation rate affected macronutrient concentrations but did not affect micronutrient concentrations including Fe, Mn, or zinc (Zn).