Evaluation of nutritional value in mustard microgreens under different light conditions during growth and storage

Abstract

Light is one of the most important growing environmental factors that can influence nutritional value, visual appearance, and overall taste of plants. The research aimed to show that lighting intensity and spectral composition may have an impact on antioxidant activity of microgreens. Mustard (Brassica juncea L.) microgreens were grown in peat substrate, photoperiod 16 h, temperature 21 ± 3°C. The experiments were conducted in a greenhouse (lat. 55°, January, natural photosynthetic photon flux density (PPFD) ∼10–15 µmol m−2 s−1) (I) with supplemental white (4000K) light-emitting diodes (LEDs) lighting, a total PPFD of 100, 150, 200, and 250 µmol m−2 s−1 was maintained; (II) for supplemental light, lamps with different spectral composition ratio consisting of red (R), blue (B), and white (W) light, maintaining PPFD of 250 µmol m−2 s−1, were used; (III) cation-exchange capacity (CEC) spectral composition consisted of deep red 61%, blue 20%, white 15%, and far red 4%, a total PPFD of 150, 200, and 250 µmol m−2 s−1 was maintained. After harvesting, the microgreens were stored in light (8 h) and dark conditions at a temperature of +4°C. Samples were taken on harvest day (D0) and after one (D1), three (D3) and five (D5) days of storage. The research data show the impact of PPFDs and light spectral composition during growth on the response of mustard microgreen antioxidant system and the dynamics of nutritionally valuable metabolites after harvest. In conclusion, lighting conditions during growth and storage may impact secondary metabolism and shelf-life of microgreens. Moreover, the selection of proper growing and storage lighting conditions is important to both economic and nutritional benefits