Date of Award
Doctor of Philosophy
Field and greenhouse studies investigated microbiological interactions in Iowa soybean (Glycine max) rhizospheres. The effects of P fertilization on mycorrhizal development and rhizobial nodule occupancy were evaluated in a 2-year field study, and follow-up greenhouse experiments evaluated rhizobial strain competition. As expected, P fertilization significantly decreased mycorrhizal infection. Unexpectedly, there was also a significant decrease in nodule occupancy of Bradyrhizobium japonicum 123;Rhizosphere microbial populations were measured in field-grown soybeans six times over the season. Rhizobia-stimulating isolates were evaluated for effect on B. japonicum 123 nodule occupancy. Two organisms statistically enhanced nodulation, but the results could not be reproduced in nonsterile soil;A preliminary study investigated fluorescent pseudomonad populations and B. japonicum serogroup 135 dominance in a calcareous and noncalcareous soil. Sterilization of the calcareous soil increased recovery of B. japonicum 123 when equal numbers of 123 and 135 were added.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Patrick M. Hicks
Hicks, Patrick M., "Ecology of Bradyrhizobium japonicum in Iowa soybean rhizosphere soil " (1986). Retrospective Theses and Dissertations. 8252.