Degree Type

Dissertation

Date of Award

1986

Degree Name

Doctor of Philosophy

Department

Agronomy

Abstract

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.

DOI

https://doi.org/10.31274/rtd-180813-6890

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Patrick M. Hicks

Language

en

Proquest ID

AAI8703711

File Format

application/pdf

File Size

89 pages

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