Using LEDs to manipulate plant growth, characteristics

With the ability to deliver specific light wavelengthswith LED lights, growers, retailers and consumers could eventually manipulatethe scent, color, flavor, postharvest life and other characteristics ofornamental and edible crops.

Author: David Kuack for Hort Americas

Both ornamental and edible plant growers are usingsupplemental lighting. Some use light to control photoperiod. Others usesupplemental light to hasten plant development by increasing the rate ofphotosynthesis.

What if you could use light to increase the flavor,aroma, color intensity, insect and disease resistance and postharvest life ofedible crops? What if you could use light to increase the fragrance, colorintensity, insect and disease resistance, flower timing and postharvest life ofornamental flowering plants? Sound like science fiction? Read on.

“We’ve known for a long time that light can affectphotosynthesis, but we are now starting to understand how light can regulate specificplant responses,” Folta said. “It’s no big surprise that light could manipulatesomething like flavors or any other aspect of plant metabolism.”

Working with other scientists at the university’sInstitute for Plant Innovation, Folta saidinitial research indicates red, far red and blue light are the three majorwavelengths that affect volatile accumulation in plants. The researchers havestudied the impact of light wavelengths on strawberries, blueberries, tomatoesand petunias.

“For ornamentals we could affect aromas, colors andflower timing by changing the light environment—the specific wavelengths,” hesaid. “It would be possible to synchronize an entire greenhouse of plants toflower at the same time just by flipping a switch. By understanding the lightspectrum and how a plant sees it, it could allow us to manipulate how a plantgrows.

“It’s almost like we can talk to the plants. It’s alanguage that is essentially a vocabulary of light wavelengths and that we canuse to influence how a plant grows.”

“LEDs allow us to deliver very precise amounts ofspecific wavelengths,” he said. “LEDs allow us to mix the light conditionsprecisely. We can pick and choose the light we want to use.”

Folta said one of the ways different light wavelengthscould be used is to customize what the final fruit, vegetable or flower wouldlook, taste and smell like.

“For example, maybe we could put the plants under bluelight for a few days and then switch to far red and then red. We know that suchsequential treatments allow us to bump up the pigments, then the nutrients andthen the flavors,” he said. “This treatment could change the way we grow, shipand sell crops, as well as how consumers store them at home.

“All plant traits are a combination of genetics and theenvironment. 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 thebox there would be this incredible aroma released.”

Folta said the research has tremendous potential for bothedible and ornamental crops.

“This research would probably have happened a longtimeago, but LED lights were prohibitively expensive,” he said. “Now that the costof LEDs and narrow band width lighting is becoming more affordable, we realisticallysee LED arrays being used in greenhouses to manipulate the way plants grow.”

“What we are doing is manipulating the plant metabolismor 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 hedoesn’t completely understand has occurred with strawberry plants.

“In the lab we have exposed strawberry plants to LEDlights and they don’t get spider mites,” he said. “We don’t know if there issomething 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 achemical 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 involvedthe same type of plant process manipulation involved inserting a gene, sprayinga chemical or other types of treatments that were labor intensive and requiredother inputs.

“Now we are looking at basically flipping a switch toturn on a low energy device,” he said. “Adding value at a low cost would be agreat thing for the horticulture industry.”