Development of an Effective Inoculant for Dry Beans

Crop Dry Bean
Start Date2016
End Date2020
Principal InvestigatorOresnik, Ivan, University of Manitoba
MPSG Financial Support$200,000
Total Project Funding$440,000

Research Objectives

  1. Identification and characterization of Rhizobium phaseolis/Rhizobium etli strains
  2. Adapting and selecting Rhizobium to commonly used bean varieties
  3. Field testing of promising Rhizobial strains

Project Description

Beans are generally poorly nodulated and rely on added nitrogen fertilizer to maximize yield.  The overall objective of this proposal is to identify an effective adapted Rhizobium etli strain(s) that can be used as an effective inoculum to reduce or eliminate the need to apply nitrogen fertilizer to beans. Of the five bacterial species that are recognized as being able to form effective nitrogen fixing nodules with beans (Rhizobium etli bv phaseoli, Rhizobium leguminosarum bv phaseoli, Rhizobium tropici, Rhizobium gallicum, and Rhizobium giardini), Rhizobium etili is generally considered the predominant species that is associated with wild bean varieties. This project will isolate and test Rhizobia that can be used to produce an effective inoculum for edible beans.  The method relies on the ability to naturally adapt the bacteria and to benchmark the changes using genomic science.

Previously isolated strains as well as strains isolated from local soils will be characterized for a number of traits, including effectiveness, emergence of nodules, onset of fixation, nodule mass and number, competitiveness for nodule occupancy and isolate genome sequencing. The “best” strains identified will be used with currently grown bean varieties.  After inoculation, structures that look like developing nodules will be harvested and used as a subsequent inoculum.   The adaptation regimes that will be used are; selection for early nodulation with lower soil temperatures and selection for nodules that are highly effective. Strains that show promise will be moved to field trials.  Plants in the field will be monitored for nodulation, nitrogen fixation and overall yield.

Fixing nitrogen fixation in dry beans – Towards more effective rhizobial inoculants for dry bean varieties – Top Crop Manager article by Carolyn King, March 15, 2020