Comprehensive Agronomic Analyses of Brassicaceae Microgreens Grown Under Different Light Emitting Diodes

Microgreens are nutrient-rich plants that can provide health benefits when used as dietary supplements. Compared with the local market, the global market has a very high demand for microgreens production. Seed availability is a limitation in the local market, and consumer preferences for mature vegetables over microgreens constitute an obstacle to the establishment of a large number of microgreen farms. Moreover, there is a lack of knowledge and awareness of the health benefits of microgreens. The study aimed to investigate the agronomic traits and biochemical analyses of five Brassicaceae microgreens (arugula, broccoli, kale, purple cabbage and green mizuna), grown hydroponically under 12 different light-emitting diodes (LEDs) in an indoor farming system. LEDs are cost-effective and energy-efficient, and have a positive effect on growth and photomorphogenesis. In terms of leaf area, microgreens grown under RGB 2 had a threefold change compared with control LEDs (white and Sanan). However, the hypocotyl length of microgreens grown under mono- and dichromatic green LEDs ranged from 5.6 to 7.65 cm, compared to the control LEDs. Biochemical assessments showed that total chlorophyll levels were doubled, carotenoid levels were tripled, total porphyrin concentrations increased three-fold, antioxidant activity was enhanced four-fold, proline content was increased three-fold, and carbohydrate levels were six times higher in all microgreens under a combination of red + green + blue LEDs compared to the control LEDs. Overall, the combination of red + blue + green LEDs yielded significantly better results than monochromatic, dichromatic and control LEDs for all microgreens in both agronomic and biochemical analyses. Hence, LEDs can be used to maximize microgreen production at a larger scale in other microgreens as well.