Philom Bios Inc.
3935 Thatcher Avenue
Saskatoon, SK Canada S7R 1A3
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Species vs. strains - what’s the difference?

Species
Because nitrogen inoculants work by infecting a plant root, each legume crop associates with a different Rhizobia species. For example, pea, lentil and faba bean will only form nodules when inoculated with Rhizobium leguminosarum; soybean when inoculated with Bradyrhizobium japonicum.

Once you have selected the right Rhizobium species, you must choose the inoculant that contains the best strain of that species since strains can vary greatly in the amount of nitrogen they fix.

Strains
Think of rhizobia strains in the same way you do seed varieties. Choosing the right seed variety can mean huge yield advantages. Improved strains can mean better nodule development, and more fixed nitrogen resulting in higher yields.

Extensive research goes into the selection of rhizobia strains. Strain selection starts in the field with the collection of native species. From the field they will go to the lab and greenhouse or growth-chambers for testing. Strains that excel in these initial trials move to more extensive lab and growth chamber work and then back to field testing. Fermentation (multiplication of the organism) and manufacturing practices must also be tested, meaning years of research go into the development of improved strains.