What began as a method to control the spread of tumbleweed plants in the desert is now showing promise for stimulating agricultural crop seed germination to potentially increase crop yields.

Jon Jackson, president of Global Neighbor, an Ohio-based small business with deep roots in spectral physics research for chemical-free weed control, says his company developed technology for the U.S. Air Force to fight the spread of tumbleweeds on 22 million acres of Edwards Air Force Base in Kern County, Calif. The work, which required weed control without herbicides or disturbance of the desert floor, was funded through a Small Business Investment Research (SBIR) grant administered through the Department of Defense. 

“After news of the weed control success at Edwards circulated, we got a bag of marestail seed in the mail from an Iowa farmer and a note attached which read: ‘If you can kill tumbleweed seeds, you can kill the marestail seed in my soybeans. Merry Christmas!’” Jackson recalls. “We’re not farmers, and until then, we hadn’t considered agricultural applications for the technology.”

After conferring with many farmers, Global Neighbors began adapting the light-treatment technology to the tough, chemical-resistant weeds faced by the nation’s growers. In 2023, the company plans to run a demonstration combine equipped with an on-board light-treatment system to process weed seeds passing through the harvester on their way to the chaff spreader.

“We found light energy from the bluish-purple segments of the visible light spectrum, along with mid-range infrared rays, damages cells near the seed’s surface responsible for root development,” Jackson says. “The treated seed is still healthy, but it is incapable of physical germination and the production of a radicle. The seed cannot establish itself in the field.”

Jackson says the plant response caught agricultural researchers off guard, so the company built a number of 1/12th scale pilot systems and supplied them to various universities. Researchers could conduct their own studies and replicate Global Neighbor’s findings, which led to another surprise for scientists working with the system.

“We got a call from a researcher who told us the system wasn’t killing the seeds, but the plants resulting from the treatment were growing like crazy,” he says. “We determined one of the LED light tubes in the machine was malfunctioning, and the seeds were only getting about half the energy required to damage them for weed-control purposes.”

That led to the realization that the same light energy waves used at lower rates stimulate seed germination and development. Global Neighbors took that knowledge to the field and discovered the results have promising implications.

“We tested our system in a 100-acre Iowa soybean field using 20 acres of light-stimulated seed and 80 acres of untreated seed,” Jackson says. “The 20-acre plot emerged more quickly and showed more robust plant growth and development throughout the season than the surrounding acres. The stimulated seed plot also produced an average of 1.1-1.2 more bushels per acre of yield.”

In another on-farm experiment, Jackson says an Ohio alfalfa producer faced with delayed planting was eager to try the light-stimulated seed.

“He planted half his hay meadow with treated seed and the other half with seed directly out of the bag,” Jackson says. “By November, the treated acres were up and green, while the untreated acres were still mainly the color of brown soil. The demarcation line between the treatments was obvious.”

The options of light-stimulation seed treatment open a number of applications for no-tillers faced with delayed planting or wet, cool planting conditions, as well as improved timing for high-value organic crop producers farming in areas with short growing seasons.

Jackson says Global Neighbor is working on another SBIR project with USDA to build and demonstrate a soybean planter equipped with light-stimulation technology. Such a system could easily become a permanent part of planting season across much of the nation in coming years.