Using LEDs to Manipulate Plant Growth, Characteristics
University of Florida associate professor Kevin Folta and other scientists at the university's Institute for Plant Innovation are studying the impact specific light wavelengths can have on plant characteristics. Photo by Tyler Jones, UF/IFAS Photography.
With the ability to deliver specific light wavelengths with LED lights, growers, retailers and consumers could eventually manipulate the scent, color, flavor, post-harvest life and other characteristics of ornamental and edible crops.
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Both ornamental and edible plant growers are using supplemental lighting. Some use light to control photoperiod. Others use supplemental light to hasten plant development by increasing the rate of photosynthesis.
What if you could use light to increase the flavor, aroma, color intensity, insect and disease resistance and post-harvest life of edible crops? What if you could use light to increase the fragrance, color intensity, insect and disease resistance, flower timing and post-harvest life of ornamental flowering plants? Sound like science fiction? Read on.
Talking to plants
Kevin Folta, interim chair and associate professor of the Horticultural Sciences Department at the University of Florida, said the fundamental idea of using light to manipulate plants is an old one.“We’ve known for a long time that light can affect photosynthesis, but we are now starting to understand how light can regulate specific plant responses,” Folta said. “It’s no big surprise that light could manipulate something like flavors or any other aspect of plant metabolism.”
Working with other scientists at the university’s Institute for Plant Innovation, Folta said initial research indicates red, far red and blue light are the three major wavelengths that affect volatile accumulation in plants. The researchers have studied the impact of light wavelengths on strawberries, blueberries, tomatoes and petunias.
“Volatiles are the chemicals that contribute to the aroma and flavor that are released,” Folta said. “Volatiles are the chemicals that are emitted that allow you to smell and taste a piece of fruit. These are the compounds that are really important in providing flavor to fruit and vegetables.”
Folta said similar changes could be made to flowering plants by manipulating the light wavelengths that the plants are exposed to.
“For ornamentals we could affect aromas, colors and flower timing by changing the light environment—the specific wavelengths,” he said. “It would be possible to synchronize an entire greenhouse of plants to flower at the same time just by flipping a switch. By understanding the light spectrum and how a plant sees it, it could allow us to manipulate how a plant grows.
“It’s almost like we can talk to the plants. It’s a language that is essentially a vocabulary of light wavelengths and that we can use to influence how a plant grows.”
Focused on LEDs
Folta said all of the research being done involves the use of LED lights.
“LEDs allow us to deliver very precise amounts of specific wavelengths,” he said. “LEDs allow us to mix the light conditions precisely. We can pick and choose the light we want to use.”
Folta said one of the ways different light wavelengths could be used is to customize what the final fruit, vegetable or flower would look, taste and smell like.
“For example, maybe we could put the plants under blue light for a few days and then switch to far red and then red. We know that such sequential treatments allow us to bump up the pigments, then the nutrients and then the flavors,” he said. “This treatment could change the way we grow, ship and sell crops, as well as how consumers store them at home.
“All plant traits are a combination of genetics and the environment. The genetics are already in place to make a quality fruit, vegetable or flower, so the LEDs allow us to manipulate what’s already there. We can tweak the environment with the LEDs to alter plant characteristics. Maybe an LED light would be placed in a box of roses. When a consumer opens the box there would be this incredible aroma released.”
Folta said the research has tremendous potential for both edible and ornamental crops.
“This research would probably have happened a longtime ago, but LED lights were prohibitively expensive,” he said. “Now that the cost of LEDs and narrow band width lighting is becoming more affordable, we realistically see LED arrays being used in greenhouses to manipulate the way plants grow.”
Endless potential
Although the initial research has focused on changing the taste of fruit and vegetables, Folta said the use of light could easily be expanded to manipulate other plant characteristics.
Kevin Folta said growers may eventually be able to synchronize an entire greenhouse of plants to flower at the same time just by flipping a switch for LED lights. Photo by Tyler Jones, UF/IFAS Photography.
“There is an increasing body of research literature that indicates some of the compounds emitted by plants and their fruit deter insects or deter fungal growth,” he said. “It may be possible that we could affect insect and disease resistance. For example, by using LED lights we could change the metabolic profile of the plant so that poinsettias would be more resistant to whitefly. This might be done by stopping production of plant compounds that attract whiteflies, or producing compounds that scare them away or even better than that may attract a predator of the whitefly."
“What we are doing is manipulating the plant metabolism or changing it in ways that we don’t necessarily understand 100 percent yet, but we know we can do it.”
An example of one of the results of the research he doesn’t completely understand has occurred with strawberry plants.
“In the lab we have exposed strawberry plants to LED lights and they don’t get spider mites,” he said. “We don’t know if there is something that the LEDs are doing to change the development of the spider mite. Or the light maybe doing something to the plant that causes it to produce a chemical the spider mites don’t like so they choose to go to a different plant. This is something that we still need to test.”
Folta said most of the previous research that involved the same type of plant process manipulation involved inserting a gene, spraying a chemical or other types of treatments that were labor intensive and required other inputs.
“Now we are looking at basically flipping a switch to turn on a low energy device,” he said. “Adding value at a low cost would be a great thing for the horticulture industry.”
This article was written by David Latchman for Hort Americas Corporate Blog.