LED Continuous Lighting Reduces Nitrate Content in Brassicaceae Microgreens

Abstract

The study was carried out to assess whether continuous lighting (CL) can be used to reduce nitrate content in Brassicaceae microgreens. Arugula (Eruca vesicaria subsp. sativa), broccoli (Brassica oleracea var. italic), mizuna (Brassica rapa var. nipposinica) and radish (Raphanus sativus var. radicula) seedlings were grown in the controlled climate chambers under 16 h or 24 h photoperiod provided by light-emitting diode (LED) or fluorescent (FLU) lamps. At the pre-harvest stage, half of microgreens were treated by CL for 3 days. The results show that nitrogen content was decreased significantly in plants grown under LED CL compared to plants grown under 16 h photoperiod. The highest decrease (by 40 %) was observed in arugula microgreens. In contrast, CL provided by FLU lamps had little effect (decrease by 11 and 6 %) on nitrate content in mizuna and broccoli and no effect in arugula and radish. Pre-harvest treatment by CL resulted in significant decrease of nitrate content in all four plant species. In conclusion, continuous LED lighting applied during microgreen cultivation or at the pre-harvest stage effectively reduces nitrate content in Brassicaceae microgreens.