UT research shows LED lights have healthy impact on vegetables, herbs

(WBIR-Knoxville) LED lights are becoming more popular, transforming the streets of Gatlinburg and decorating Christmas trees across the country, but researchers at the University of Tennessee discovered the technology has positive impacts on herbs and vegetables.

LED stands for light emitting diodes, and are known to be cost effective and energy efficient.

Back in 2008, Gatlinburg switched to LED lights, with 3 million bulbs illuminating the city for 120 winter days at the cost of what the city used to pay for just three days of electricity.

While they're eye-catching, Dean Kopsell, a professor with U.T.'s Plant Sciences Department, said LED lighting can also be healthy.

"We found out that they can really dramatically increase plant physiology, increase mineral nutrient levels, and also increase antioxidant levels, which are very important for us in the diet," said Kopsell.

Kopsell said plants only need a small percentage of sunlight rays, but under LED lighting, researchers can intensify the light plants do need, saving them energy. He said while LED lights come in all colors, blue and red are the most important to plant growth.

"We're looking at the important impacts of red and blue but more importantly we're adjusting the ratios of red and blue," said Kopsell. "So on a normal day, we're taking the percent blue that would normally be in sunlight, and we're increasing that by three or four fold, and we're really improving the nutritional and mineral and antioxidant levels in the crops. "

Kopsell and Dr. Carl Sams studied the impacts on herbs and specialty vegetables, like kale. He said the already healthy crop produced even higher levels of nutrients, like calcium, potassium, iron, and even anti-cancer components.

The LED lights also emit less heat, especially compared to high pressure sodium lamps found in greenhouses, which are usually 1,000 watts each.

"You can see they've got a yellow tint, because they have yellow light in them. They're hot and can wilt the tops of the plants closest to the light," said Kopsell. "But you don't have that detrimental heat impact under blue and red LEDs."

Kopsell said the research could have a future impact on metropolitan areas, giving growers an indoor option.

"Right now, this idea of using urban farming, or vertical farming, going into urban areas and trying to create plant production systems in warehouses and buildings is really important and really starting to pickup in a lot of the major metropolitan cities," said Kopsell. "But it's going to be really hard to use high pressure sodium light in those areas just because of the heat buildup. "

Kopsell said LED lighting could be supplement to greenhouse growing.

"Most of the people I've been talking to across the country, they want to be able to grow plants inside," said Kopsell. "We're going to be able to grow crops in urban areas or in arid land areas where we wouldn't be able to grow them outside due to soil conditions or temperature conditions. "

Kopsell said LED technology is still expensive. The panels U.T. is using cost $700 each, but were engineered for the research.


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