University of Wisconsin-Madison scientists have identified bacteria that increased corn yields by 5 percent to 10 percent in preliminary field trials in five Midwestern states.

"Ours is the first group to isolate and identify strains of bacteria from inside plants that can increase corn yields," says Eric Triplett, a microbial ecologist with the Department of Agronomy. The discovery may lead to a new product for farmers — seed corn that comes coated with growth-enhancing bacteria.

Corn is Wisconsin's leading crop. Last fall, farmers harvested approximately 340 million bushels of corn from 2.6 million acres in the state.

Triplett presented the findings last summer at a meeting in Australia. The meeting attracted scientists from around the world who are interested in bacteria that can supply nitrogen to crops such as wheat, rice and corn. The Wisconsin research will be published in the Australian Journal of Plant Physiology. The College of Agricultural and Life Sciences scientists who worked on the project included technician Patrick J. Riggs, graduate research assistants Marisa Chelius and Leonardo Iniguez, and maize geneticist Shawn Kaeppler.

Triplett began the research on corn after Brazilian scientists discovered two bacteria that live inside sugar cane and produce all the nitrogen the crop needs. The Wisconsin team then began a systematic search for bacteria that live inside corn plants and can capture nitrogen from the atmosphere.

The team evaluated 23 bacterial strains including ones from Brazil and Egypt, along with several the UW-Madison researchers isolated from corn and switch grass plants growing on nitrogen-poor soils in Wisconsin. They eliminated most of the strains after greenhouse tests and early field trials in Wisconsin.

The researchers found seven promising strains. Those strains included two of the bacteria originally identified from sugar cane and five that the team isolated in Wisconsin.

During 2000, the researchers conducted field trials with five elite corn hybrids at the College's Arlington and Lancaster Agricultural Research Stations, as well as at sites in Iowa, Illinois, Nebraska and Indiana. The results showed that the bacteria increased yields an average of 5 to 10 percent.

The scientists have applied for a patent on four of the bacterial strains through the Wisconsin Alumni Research Foundation. Several companies have express an interest in licensing the technology, according to Triplett. He hopes that strains will be test marketed within a few years.

Triplett says that it's not yet clear if the same bacterial strains would enhance the yields of other corn hybrids. However, he says, research shows that these strains will enter several other plants including wheat and rice.

Just how the bacteria improve corn yields remains a mystery. It's unlikely that the bacteria supply corn with a significant amount of nitrogen, according to Triplett.

"We never found bacterial strains that could supply enough nitrogen to compensate for nitrogen-deficient conditions," Triplett says. "The field sites where we did the tests had plenty of nitrogen."

Triplett says finding bacteria that will supply corn with nitrogen remains a long-term goal. Corn that requires little if any nitrogen fertilizer could save Wisconsin farmers millions of dollars in production costs each year while reducing problems associated with too much nitrogen in the environment.

Triplett will continue studies to determine how the bacteria enter corn plants and discover how they enhance yields.

The research was supported by state funding to the College of Agricultural and Life Sciences, and by grants from the College, Cargill, Inc., and the Consortium for Plant Biotechnology Research.