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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.01153

Response of mustard microgreens to different wavelengths and durations of UV-A LEDs

  • 1Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Lithuania
  • 2Institute of Photonics and Nanotechnology, Vilnius University, Lithuania

Ultraviolet A (UV-A) light-emitting diodes (LEDs) could serve as an effective tool for improving the content of health-promoting bioactive compounds in plants in controlled environment agriculture (CEA) systems. The goal of this study was to investigate the effects of UV-A LEDs at different wavelengths (366, 390, and 402 nm) and durations (10 and 16 h) on the growth and phytochemical contents of mustard microgreens (Brassica juncea L. cv. ‘Red Lion’), when used as supplemental light to the main LED lighting system (with peak wavelengths of 447, 638, 665 and 731 nm). Plants were grown for 10 days under a total photon flux density (TPFD) of 300 µmol m-2 s-1 and 16-h light/8-h dark period. Different UV-A wavelengths and irradiance durations had varied effects on mustard microgreens. Supplemental UV-A radiation did not affect biomass accumulation; however, the longest UV-A wavelength (402 nm) increased the leaf area of mustard microgreens, regardless of the duration of irradiance. The concentration of the total phenolic content and α-tocopherol mostly increased under 402 nm UV-A, while that of nitrates increased under 366 and 390 nm UV-A at both radiance durations. The contents of lutein/zeaxanthin and -carotene increased in response to the shortest UV-A wavelength (366 nm) at 10 h irradiance as well as longer UV-A wavelength (390 nm) at 16 h irradiance. The most positive effect on the accumulation of mineral elements, except iron, was observed under longer UV-A wavelengths at 16 h irradiance. Overall, these results suggest that properly composed UV-A LED parameters in LED lighting systems could improve the nutritional quality of mustard microgreens, without causing any adverse effects on plant growth.

Keywords: light emitting diodes, UV-A, Growth, Antioxidants, mineral elements, mustard microgreens

Received: 04 Apr 2019; Accepted: 23 Aug 2019.

Copyright: © 2019 Brazaitytė, Viršilė, Samuolienė, Vaštakaitė-Kairienė, Jankauskienė, Miliauskienė, Novičkovas and Duchovskis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Aušra Brazaitytė, Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Babtai, LT-54333, Kaunas, Lithuania, a.brazaityte@lsdi.lt