Effect of Low Light Intensity With Supplemental Far-Red Light on Growth, Yield and Quality of Broccoli Microgreens

One of the main obstacles to indoor agriculture is the high expense of lighting energy. The purpose of this study was to investigate how to grow broccoli microgreens under low light with higher yield and better quality. Broccoli seedlings were exposed to different photosynthetic photon flux densities (PPFD) ranging from 50 to 150 μmol/m² s, along with supplemental far-red (FR) light (20% of total photon flux density (TPFD)) at 50 and 75 μmol/m² s. Broccoli grown under 50, 75, and 100 μmol/m² s exhibited the highest fresh weight. As light intensity decreased, the hypocotyl length of broccoli microgreens increased. High chlorophyll, carotenoid, and anthocyanin contents were observed at 100 and 150 μmol/m² s, while ascorbic acid and total phenolics were higher at 50 and 75 μmol/m² s. The addition of FR light resulted in increased plant height, fresh weight, and antioxidant concentration. However, there was a significant decrease in total phenolic content. These results indicate that broccoli microgreen can adapt to low light with high yield and quality. Addition of FR under low light can further increase microgreen yield and plant height. Furthermore, postharvest quality and shelf-life of microgreens under 50 and 75 μmol/m² s were better than those under 100 and 150 μmol/m² s. This research provides the platform for further managing microgreen growth under low light to reduce energy consumption for controlled environment agriculture (CEA).