How sole-source LEDs impact growth of Brassica microgreens

July 27, 2016, American Society for Horticultural Science
Photo of mustard microgreens grown under sole-source (SS) lighting using light-emitting diodes (LEDs) with a light ratio of red:green:blue 74:18:8 (R74:G18:B8). Credit: Joshua Craver.

Microgreens and baby greens are a relatively new specialty crop seen in many upscale markets and restaurants. Favored by chefs and consumers, microgreens are used to enhance the flavor, color, and texture of foods, and some species have the added benefit of high concentrations of health-promoting phytochemicals. As consumer demand for these specialty crops increases, commercial greenhouse growers are becoming more interested in producing microgreens for market, and scientists are working to find the best production practices for growers. A study published in the May 2016 issue of HortScience offers important recommendations for lighting practices in microgreen production systems.

The study was designed to investigate the effects of sole-source (SS) light-emitting diodes (LEDs) of different light qualities and intensities on , morphology, and of the Brassica microgreens. Corresponding author Roberto Lopez explained that LEDs offer many advantages over conventional light sources, including the ability to select light qualities and intensities that have beneficial effects on plants. "Although previous reports have indicated that (LI) or light quality (LQ) from SS LEDs had an effect on the growth of microgreens and baby greens, little work has been published on the interaction between LI and LQ on the growth and nutrient content of Brassica microgreens," Lopez said.

Microgreens purple kohlrabi, mizuna, and mustard were grown in hydroponic tray systems placed on multilayer shelves in a walk-in growth chamber. The experiments used LED arrays providing light ratios of red:green:blue 74:18:8 (R74:G18:B8), red:blue 87:13 (R87:B13), or red:far-red:blue 84:7:9 (R84:FR7:B9) with three light intensity treatments. The researchers analyzed treatments for effects on microgreen growth, morphology, and nutrient content.

For all three species of Brassica, hypocotyl length decreased as light intensity increased, while percent dry weight increased with increasing light intensity (regardless of light quality). Additionally, nutrient content of both macro- and micronutrients decreased as light intensity increased for all three species. Relative chlorophyll content of mizuna and mustard was not significantly influenced by light intensity or light quality; however, leaf area of kohlrabi generally decreased and relative chlorophyll content increased with increasing light intensity.

The authors said that growers can use the data presented in the study to select the best " recipes" to achieve preferred growth characteristics of Brassica microgreens.

Explore further: End-of-production LED lighting increases red pigmentation in lettuce

Related Stories

LED treatments enhance lettuce phytochemicals, antioxidants

May 10, 2016

Increasingly, vegetables are being efficiently grown using soilless techniques such as hydroponics. Hydroponic systems are favored for their ability to improve water and nutrient use efficiency and crop yields, and have the ...

Effects of spectral quality, intensity of LEDs

May 9, 2016

In horticultural operations, light-emitting diode (LED) lamps are becoming recognized as an important advance in artificial lighting. Among other benefits, LED lighting systems can offer durability, long operating lifetimes, ...

Researchers test effects of LEDs on leaf lettuce

November 19, 2013

In the life cycle of plants, most developmental processes are dependent on light. Significant biological processes such as germination, shade avoidance, circadian rhythms, and flower induction are all affected by light. Recent ...

Specialty greens pack a nutritional punch

January 24, 2014

"Microgreens" is a marketing term used to describe edible greens which germinate from the seeds of vegetables and herbs and are harvested without roots at the seedling stage. The plants at the seedling stage have two fully ...

Recommended for you

Research offers new insights into malaria parasite

May 18, 2018

A team of researchers led by a University of California, Riverside, scientist has found that various stages of the development of human malaria parasites, including stages involved in malaria transmission, are linked to epigenetic ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.