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dc.contributor.advisorStanghellini, M. E.en_US
dc.contributor.authorTedla, Tesfaye
dc.creatorTedla, Tesfayeen_US
dc.date.accessioned2011-10-31T17:38:16Z
dc.date.available2011-10-31T17:38:16Z
dc.date.issued1991en_US
dc.identifier.urihttp://hdl.handle.net/10150/185455
dc.description.abstractTripartite rhizosphere (host, fungus, and rhizobacterial) interactions were studied to determine the mechanism(s) associated with lack of oospore germination and host colonization by Pythium aphanidermatum at soil temperatures below 27°C. Results indicate that rhizobacterial competition for nutrients was responsible for the general supression of pathogen activity at low soil temperature. In general less than 25% host colonization occurred at 20°C whereas greater than 90% colonization recorded at 27°C. However, when bacterial competition was reduced or eliminated by the addition of vancomycin, host colonization at 20°C increased to 83%. Competition between the fungus and the resident rhizobacterial population was also shown to occur prior to any significant increase in bacterial multiplication. The generation time of bacteria in undisturbed rhizosphere soil was estimated at about 8 hrs at both 20 and 27°C. Whereas both the rate and percentage germination of oospores were increased significantly at both 20 and 27°C in the rhizosphere soil if bacterial competition was inhibited by the addition of vancomycin.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectDissertations, Academicen_US
dc.subjectBacteriology, Agricultural.en_US
dc.titleDistribution, dynamics and interactions of microorganisms in undisturbed rhizosphere of mature sugar beets.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.identifier.oclc710296023en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberHine, Richard B.en_US
dc.contributor.committeememberGilbertson, Robert L.en_US
dc.contributor.committeememberMisaghu, I. J.en_US
dc.contributor.committeememberBriggs, Robert E.en_US
dc.identifier.proquest9124163en_US
thesis.degree.disciplinePlant pathologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
refterms.dateFOA2018-09-03T09:11:38Z
html.description.abstractTripartite rhizosphere (host, fungus, and rhizobacterial) interactions were studied to determine the mechanism(s) associated with lack of oospore germination and host colonization by Pythium aphanidermatum at soil temperatures below 27°C. Results indicate that rhizobacterial competition for nutrients was responsible for the general supression of pathogen activity at low soil temperature. In general less than 25% host colonization occurred at 20°C whereas greater than 90% colonization recorded at 27°C. However, when bacterial competition was reduced or eliminated by the addition of vancomycin, host colonization at 20°C increased to 83%. Competition between the fungus and the resident rhizobacterial population was also shown to occur prior to any significant increase in bacterial multiplication. The generation time of bacteria in undisturbed rhizosphere soil was estimated at about 8 hrs at both 20 and 27°C. Whereas both the rate and percentage germination of oospores were increased significantly at both 20 and 27°C in the rhizosphere soil if bacterial competition was inhibited by the addition of vancomycin.


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