Interactions between Rhizobium japonicum and Soybean Rhizosphere Bacteria1
- R. Stewart Smith and
- Robert H. Miller2
The success of soybean inoculation is influenced by the survival of Rhizobium japonicum as a free-living soil bacterium. One factor affecting survival is the interaction of R. japonicum with other rhizosphere bacteria. The objective of this study was to observe interactions of R. japonicum and soybean rhizosphere bacteria with techniques of increasing complexity with and without the soybean host (Glycine max (L.) Merrill). Eight of nine rhizosphere isolates inhibited R. japonicum on agar. The degree of inhibition was dependent upon the strain of rhizobia, the bacterial isolate, and the agar medium. The interactions of R. japonicum and rhizosphere bacteria with the soybean host (Glycine max (L.) Merrill) were evaluated by observing soybean nodulation, plant weight, and plant elemental analysis. Nodulation was not affected by rhizosphere bacteria when plants were grown in vermiculite or in sterile soil. One rhizosphere isolate, which failed to inhibit R. japonicum on agar, caused severe soybean tap root injury under gnotobiotic growth in soil. Even with the root damage, nodulation was unaffected with this bacterium-R. japonicum combination.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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