Effects of Light-Emitting Diodes (LEDs) on Growth, Nitrates and Osmoprotectant Content in Microgreens of Aromatic and Medicinal Plants

Abstract

Microgreens are receiving increasing attention due to their high content of bioactive components and their importance to human health. These emerging food products can be obtained from the seeds of different plant species, including aromatic herbs. Aromatic microgreens are gaining popularity as new functional food products. In this study, we investigated the effects of different light-emitting diode (LED) lamp spectra on the growth, pigments, nitrates, and osmoprotectant content of microgreens of Ocimum basilicum L., Trigonella foenum-graecum, Anethum graveolens, and Anthriscus cerefolium plants. Three types of artificial LED lamps were used: T0 as artificial white light, T1 as a continuous light-emitting diode with a longer blue wavelength, and T2 as a continuous light-emitting diode with a longer red wavelength. The results obtained showed that the three types of LED light had significant effects on the different parameters studied. In relation to growth parameters, such as fresh weight (FW) and microgreen height (H), the T2 treatment was most effective for fenugreek, dill, and chervil. However, in basil plants, FW and H values were higher under T1 treatment. Regarding nitrate accumulation, both T1 and T2 treatments reduced the content of this nutrient in the different species studied here. Finally, levels of chlorophyll, carotenoid, glucose, proline, and proteins were all higher in plants cultivated under T1 and T2 treatments than in control plants.