The right ratio of blue and red LEDs boosts leaf growth and antioxidant compounds in lettuce

Nov. 22, 2013
Cheongju, South Korea--Adding to the fast-growing body of knowledge on the use of LED illumination in horticulture, scientists at Chungbuk National University published a study in which they exposed red and green leaf lettuce to six different LED lighting treatments, then examined growth characteristics including the fresh and dry weights of shoots and roots, shoot-to-root ratio, total leaf area, and chlorophyll content.
(Courtesy of Ocean Optics)
Monitoring LED emission spectra in a greenhouse enables growth patterns of plants to be correlated with the illumination spectra.
Monitoring LED emission spectra in a greenhouse enables growth patterns of plants to be correlated with the illumination spectra.

Cheongju, South Korea--Adding to the fast-growing body of knowledge on the use of LED illumination in horticulture, scientists at Chungbuk National University published a study in which they exposed red and green leaf lettuce to six different LED lighting treatments, then examined growth characteristics including the fresh and dry weights of shoots and roots, shoot-to-root ratio, total leaf area, and chlorophyll content. Chlorophyll fluorescence, antioxidant capacity, phenolic concentration, and flavonoid concentration were also measured in the study.

The scientists concluded that the growth-characteristic results for the two lettuce cultivars grown under various ratios of blue (456 nm) to red (655 nm) LEDs confirmed that red LED light improves lettuce growth rate. Blue:red ratios tested were 0:100, 13:87, 26:74, 35:65, 47:53, and 59:41.

The experiments confirmed that blue and red LEDs have a positive effect on the accumulation of antioxidant phenolic compounds and lettuce growth, respectively. "Red light irradiation in the absence of blue light was effective at stimulating the biomass accumulation of lettuce plants; however, this lighting alone induced abnormal leaf shape and had a negative effect on polyphenolics and antioxidant levels," the scientists say. They recommend a mixture of blue and red LEDs to enhance lettuce-crop quality and yield in closed-type plant-production systems; the best results for lettuce arose from the blue:red ratios 35:65, 47:53, and 59:41.

That makes scents

Past studies elsewhere have shown the beneficial effects of other LED wavelength bands on plant growth; for example, researchers from the U.S. Department of Agriculture (Beltsville, MD) have used UV LEDs emitting at about 290 nm (the UVB range) to make lettuce darker and redder, as well as to keep strawberries from getting moldy. For crops including petunia, tomato, strawberry, and blueberry, red and far-red LED light can be used to manipulate scents of the fruits and flowers.

For more info, see: http://hortsci.ashspublications.org/content/48/8/988.abstract

Source: http://ashs.org/pressrelease/index.php?option=com_content&view=article&id=1302:researchers-test-effects-of-leds-on-leaf-lettuce-&catid=1:hortscience&Itemid=3

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

Sponsored Recommendations

Next generation tunable infrared lasers

Nov. 28, 2023
Discussion of more powerful and stable quantum cascade tunable infrared lasers, applications, and test results.

What AI demands mean for data centers

Nov. 28, 2023
The 2023 Photonics-Enabled Cloud Computing Summit assembled by Optica took an aggressive approach to calling out the limitations of today’s current technologies.

SLP feature for lighting control available on cameras offering

Nov. 28, 2023
A proprietary structured light projector (SLP) feature is now available on the company’s camera series, including the ace 2, boost R, ace U, and ace L.

Chroma Customer Spotlight - Dr. David Warshaw, About his Lab

Nov. 27, 2023
David Warshaw, Professor and Chair of Molecular Physiology and Biophysics at the University of Vermont (UVM), walks us through his lab. Learn about his lab’s work with the protein...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!