Histological Analyses of Five Brassicaceae Microgreens Grown under Different Light-Emitting Diodes in an Indoor Farming System

Microgreens are small plants that have not yet reached the seedling stage. Microgreens research is gaining momentum because of its benefits and advantages. However, anatomical assessment under light-emitting diodes (LEDs) is limited. This study aims to investigate the anatomy of Brassicaceae microgreens (arugula, broccoli, kale, purple cabbage, and green mizuna) grown under 12 different LED spectra under indoor conditions. The histology of cotyledonary leaves of the selected microgreens showed that chloroplasts were well-developed and abundant under combination LEDs compared to monochromatic and dichromatic LEDs. The cross-section of the cotyledon cell structure, vascular bundle, xylem, and phloem of all microgreens grown under RGB1, RGB2, and RGB3 were also clearly visible compared to the other LED spectra (monochromatic and dichromatic). For arugula, broccoli, kale, and purple cabbage grown under control LEDs (white and Sanan), histological analysis showed that the structure of xylem and phloem cells is less identical and not easily discernible except for the green mizuna microgreen. Therefore, the histological analysis of the cotyledonary leaves under the LED combinations confirmed better structural integrity, cell differentiation, and a higher number of chloroplasts in arugula, broccoli, kale, purple cabbage, and green mizuna microgreens. Microgreens can easily grow under indoor conditions; therefore, it is necessary to understand the ability of plants to cope with a dynamic environment.