Optimizing Nitrogen Fixation by Crop-Rhizobial Interactions in Peas and Lentils.

Nitrogen fixation in legumes requires symbiotic interaction of plants with rhizobia bacteria. Increasing this N fixation could both increase crop productivity and reduce fertilizer costs. Optimizing this symbiosis may require improving selections of each partner of the symbiosis. In this study five varieties of lentils and five varieties of peas were tested with 13-15 commercial strains of Rhizobium leguminoserum bv. Viciae to determine both better strains for inoculation and varieties with high potential as breeding lines.

Inoculated plants were grown for 6 weeks. Below and above ground biomass, numbers of nodules, and the proportion of plant N provided by fixation were determined. All plant parameters were positively correlated to N fixation.The N fixed in lentils was significantly influenced by both crop variety and rhizobial strain. Eston and Meritt varieties fixed the highest amount of N respectively at 80.8% and 80.5%. In peas the amount of fixed N reached 91.3 % and 90.5% respectively in Shawnee and Bohatyr, and different strains had no effect on the amount of N fixation. Legume varieties had a significant influence on N fixation suggesting that crop breeding to support higher rates of N fixation may be possible.