Competition of Rhizobium japoncium strains in early stages of soybean nodulation

• Published in: Applied and environmental microbiology Vol. 46; no. 4; pp. 870 - 873
• Main Authors: Kosslak, R M, Bohlool, B B, Dowdle, S, Sadowsky, MJ
• Format: Journal Article
• Language: English
• Published: 01-01-1983
• Subjects: Glycine max
• ISSN: 0099-2240

The effect of preexposure of soybean (Glycie max L. Merrill) roots to R. japonicum strains and subsequent establishment of other strains in the nodules were investigated by using combinations of effective strains (USDA 110 and USDA 138) and effective-ineffective strains (USDA 110 and SM-5). Strain USDA 110 was a better competitor than either USDA 138 or SM-5 on cultivars Lee and Peking. However, when either of the two less-competitive strains was inoculated into 2-day-old seedlings before USDA 110 was, their nodule occupancy increased significantly on both cultivars. When the ineffective strain SM-5 was used as the primary inoculum, followed by USDA 110 72 h later, the percentage of nodules containing SM-5 increased from 7 to 76%. The results indicate that the early events in the nodulation process of soybeans are perhaps the most critical for competition among R. japonicum strains.