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Bacteria-Fungi Combo Could Boost Pea Growth

American and Russian scientists collaborating on sustainable methods of farming this spring will field test a two-pronged approach to growing dry edible peas.

On one front, they'll coat the legume crop's seed with an experimental inoculant containing two kinds of yield-boosting microbes: Rhizobia bacteria and Mycorrhiza fungi. The bacteria supply the pea plant's roots with nitrogen "fixed" from the air, while the fungi provide phosphorus "mined" from the soil, according to Fred Muehlbauer. He's a geneticist with the Agricultural Research Service's Grain Legume Genetics and Physiology Research Unit, Pullman, Wash.

Muehlbauer is collaborating with Alexey Borisov, a microbiologist at the All-Russia Research Institute for Agricultural Microbiology in St. Petersburg. A science division of the North Atlantic Treaty Organization is funding their three-year project, aimed at improving pea production as a food crop and as "green manure" that can naturally fertilize the soil.

Secondly, to get the most out of the approach, researchers are using the inoculant in concert with pea varieties especially adept at forming symbiotic relationships with the Rhizobia and Mycorrhiza. They've developed five new types of microbe-friendly peas based on careful screening of 26 total varieties and breeding lines from ARS and Russian germplasm collections. This spring, at Pullman and near the Russian city of Orel, they'll evaluate the new peas' responses--including growth and yield--to four treatments: rhizobium-only inoculation, mycorrhiza only, rhizobium plus mycorrhiza, and a control group.

Pea growers normally inoculate pea seed with the Rhizobia, but the scientists think a better tactic may be to apply the bacteria and Mycorrhiza fungi together. Indeed, in his early field studies, Borisov observed seed yield increases of up to 30 percent in some, but not all, of the 26 pea lines he tested. One inoculated pea variety produced 25 percent bigger seed than fertilized controls.

Read more about the research in the February issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.