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Microbial Ecology and Horticultural Sustainability of Organically and Conventionally Managed Apples

dc.contributor.advisorWalsh, Christopher Sen_US
dc.contributor.authorOttesen, Andreaen_US
dc.date.accessioned2009-03-24T05:49:35Z
dc.date.available2009-03-24T05:49:35Z
dc.date.issued2008en_US
dc.identifier.urihttp://hdl.handle.net/1903/9017
dc.description.abstractObjectives: Organically and conventionally managed apple trees (Malus domestica Borkh) were evaluated for three growing seasons (2005-2007) to examine the impact of organic and conventional pesticide applications on the microbial ecology of phyllosphere and soil microflora. An important objective was to establish if organic or conventional selection pressures contribute to an increased presence of enteric pathogens in phyllosphere microflora. The horticultural and economic sustainability of the organic crop was also compared to the conventional crop with regard to fruit yield and input costs. Methods: Microbial populations from phyllosphere and soil environments of apple trees were evaluated using clone libraries of 16S rRNA gene fragments. Clones were sequenced and software was used to assess diversity indices, identify shared similarities and compute statistical differences between communities. These measurements were subsequently used to examine treatment effects on the microbial libraries. Phyllosphere Results: Eight bacterial phyla and 14 classes were found in this environment. A statistically significant difference between organically and conventionally managed phyllosphere bacterial microbial communities was observed at four of six sampling time points. Unique phylotypes were found associated with each management treatment but no increased human health risk could be associated with either treatment with regard to enteric pathogens. Soil Results: Seventeen bacterial phyla spanning twenty-two classes, and two archaeal phyla spanning eight classes, were seen in the 16S rRNA gene libraries of organic and conventional soil samples. The organic and conventional soil libraries were statistically different from each other although the sampling depth was not sufficient to make definitive inference about this environment. Horticultural Results: Fruit yields from organically managed apple trees were from one half to one third of the yields from conventionally managed trees. Based on input costs, organic fruit was about twice as expensive to produce. Asian pears (Prunus serotina) were also included in this horticultural analysis and showed greater field tolerance as an organic specialty niche crop than apples.en_US
dc.format.extent9066993 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.titleMicrobial Ecology and Horticultural Sustainability of Organically and Conventionally Managed Applesen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentPlant Science and Landscape Architecture (PSLA)en_US
dc.subject.pqcontrolledAgriculture, Horticultureen_US
dc.subject.pqcontrolledBiology, Microbiologyen_US
dc.subject.pqcontrolledAgriculture, Food Science and Technologyen_US
dc.subject.pquncontrolledapplesen_US
dc.subject.pquncontrolledconventionalen_US
dc.subject.pquncontrolledGram negativeen_US
dc.subject.pquncontrolledmicrobial ecologyen_US
dc.subject.pquncontrolledorganicen_US


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