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dc.contributor.authorIvens, Harris
dc.contributor.otherQueen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.))en
dc.date.accessioned2018-01-11T18:59:59Z
dc.date.available2018-01-11T18:59:59Z
dc.identifier.urihttp://hdl.handle.net/1974/23828
dc.description.abstractStrategies to increase crop yields and drought stress tolerance are urgently needed to meet future global food demands in a changing climate. Although the effects of fertilizer application and drought stress in agriculture have each been researched extensively, the combined impacts of these two factors on crop yield, soil microbes, and nutrient availability are not well understood. High soil nitrogen availability promotes rapid plant growth, and increases leaf sap nitrate concentrations, but reduces carbon-based solute concentrations. By contrast, plants accumulate carbon-based solutes in response to drought. This project evaluates changes in leaf sap composition in response to fertilizer and water availability, to determine whether a trade-off exists between reduced leaf sap carbon concentrations associated with rapid plant growth, and subsequent tolerance to water-limitation. My thesis research centred on a greenhouse experiment to investigate the effects of nitrogen and potassium fertilizer (NK) additions at three levels on soil microbes, shoot growth, and leaf sap composition of replicate (n=9) Collard greens (Brassica oleracea) before and after a moderate water-limitation treatment. Increasing levels of NK addition progressively enhanced shoot biomass, and the medium and high levels doubled leaf sap total nitrogen and halved leaf sap carbon concentrations after 63 days of growth (i.e. at the end of the ‘normal’ trial). However, after three-weeks of subsequent water-stressed conditions (i.e. at the end of the normal plus water-limitation phases – the ‘water limitation’ trial), shoot biomass increases maintained a similar growth pattern to the normal trial, indicating that low leaf sap carbon concentrations did not reduce the subsequent shoot growth rate under water-limited conditions. Soil microbial N accumulation was equivalent across all fertilizer addition levels at the end of the normal trial, but increased progressively with NK addition after the water-limitation trial. Finally, leaf sap nitrate correlated closely with soluble soil nitrate, indicating that the former may provide an effective low-cost in-field test to determine the status of soluble nitrogen in agricultural soils. Overall, I found new and important relationships among leaf sap, soil microbial biomass, and bulk soil nutrient pools that will contribute to the improvement of soil management practices to meet the agricultural challenges of the future.en_US
dc.language.isoenen_US
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectLeaf Sapen_US
dc.subjectMetabolicen_US
dc.subjectSoilen_US
dc.subjectMicrobial Biomassen_US
dc.subjectNitrogenen_US
dc.subjectPotassiumen_US
dc.subjectWater Limitationen_US
dc.subjectCropen_US
dc.subjectAgricultureen_US
dc.subjectFertilizer Gradienten_US
dc.subjectPlanten_US
dc.subjectCollard Greensen_US
dc.subjectBrassica oleracea var. acephalaen_US
dc.titleAs Above so Below? - Impacts of Water Limitation on Growth and Nutrient Accumulation of a Crop Plant and its Soil Microbes Across a Fertility Gradienten_US
dc.typeThesisen
dc.description.degreeMaster of Scienceen_US
dc.contributor.supervisorGrogan, Paul
dc.contributor.departmentBiologyen_US
dc.embargo.termsThis restriction is requested to ensure future manuscripts submitted for publication will be seen as unpublished works by potential journals. I plan to release the restriction once manuscripts have been published in approximately one year. However, I request a 3 year restriction to provide sufficient time to ensure the publication of multiple manuscripts based on this research.en_US
dc.embargo.liftdate2023-01-11T14:40:41Z


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