Microgreens, defined as tender immature greens produced from seeds of vegetables, herbs,
or grains, have become a lucrative specialty crop globally. These nutrient-rich microgreens
are valued for their ability to enhance the colour, flavour, texture, and nutritional value of various
dishes. In controlled environments like greenhouses and plant factories with LED grow lights, the choice of
lighting plays a crucial role in production efficiency and cost-effectiveness. While fluorescent lamps were
traditionally used, light-emitting diodes (LED) Grow lights have gained popularity due to advantages like low
heat output, energy efficiency, tunability, and a long lifespan.
Recent study titled ‘Continuous LED Lighting Enhances Yield and Nutritional Value of Four Genotypes of Brassicaceae
Microgreens’ delve into the world of microgreens, specifically arugula, broccoli, mizuna, and radish, to explore the
impact of continuous lighting (CL) with the help of LED grow lights and different light spectra on their growth and nutritional
quality. Employing light-emitting diode (LED) Grow lights and fluorescent lighting, the findings suggest that a 24-hour photoperiod
significantly enhances the yield and nutritional value of these Brassicaceae microgreens. The study explores the nuances of light quality,
photoperiod, and their interplay, shedding light on a promising strategy for economic and nutritional benefits in microgreen production.
LED Grow light technology, with its narrowband-emitting diodes and near monochromatic spectrum in the PAR band, allows for precise control of the light environment, influencing plant growth and bioactive compound synthesis. This study focuses on Brassicaceae microgreens—arugula, broccoli, mizuna, and radish—and investigates the effects of continuous lighting (CL) delivered by LED Grow Lights and fluorescent lamps.
Microgreens were cultivated under four combinations of two photoperiods (16 h and 24 h) providing daily light integral (DLI) of 15.6 and 23.3 mol /m2 /day, respectively, with two light spectra resulted in following outcomes:
Continuous LED lighting (LED-CL) with the help of LED Grow Lights significantly enhanced the growth and productivity of microgreens, leading to higher fresh and dry weights, increased leaf mass per area, and a higher robust index. The use of CL with the help of LED Grow Lights also accelerated the emergence of the first true leaf, suggesting a potential reduction in time to harvest.
Microgreens exhibited optimal growth at higher PAR levels, with the 450 µmol /m² /s treatment resulting in significantly increased fresh and dry weights. This highlights the positive correlation between light intensity, photosynthetic activity, and biomass production.
While CL resulted in a decrease in total chlorophyll content for arugula and mizuna, LED-CL treatments with the help of LED Grow Lights showed higher levels of chlorophyll a/b and carotenoid-to-chlorophyll ratios.
Higher PAR levels positively impacted chlorophyll synthesis, leading to increased chlorophyll a/b ratios and enhanced carotenoid-to-chlorophyll ratios. The microgreens under 450 µmol /m2 /s PAR exhibited robust photosynthetic pigment content, indicative of improved light capture efficiency.
Microgreens treated with CL with the help of LED Grow Lights exhibited a significant increase in anthocyanins and flavonoids, particularly under specialised grow light spectrum. This correlated with visible colour changes, suggesting an improvement in phytochemical content and potential health benefits.
CL from LED Grow Lights induced mild oxidative stress, evidenced by higher hydrogen peroxide (H2O2) content. However, plants responded by accumulating antioxidants such as proline, anthocyanins, and flavonoids. The activity of antioxidant enzymes (CAT, SOD, APX, and GPX) increased, indicating a protective response to oxidative stress.
The LED light ratio of red: green: blue was 50.3: 21.1: 17.6 in this study. This specific LED spectrum played a crucial role in influencing plant responses, with LED-CL Grow Light treatments consistently showing more pronounced effects compared to fluorescent lighting.
Study of the LEDs spectrums influence on the spirulina platensis growth in batch culture is :
available at
https://www.researchgate.net/publication/357740757
_Continuous_LED_Lighting_Enhances_Yield_and
_Nutritional_Value_of_Four_Genotypes_of_Brassicaceae
_Microgreens