Browsing by Subject "rhizosphere"
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Item Biogeochemical Interactions And Ecological Consequences Of Sulfur In Stands Of Wild Rice(2020-05) LaFond-Hudson, SophiaWild rice is an ecologically and culturally important plant that typically grows in lakes and rivers in Minnesota that have low sulfate concentrations. Previous work demonstrated that elevated sulfate concentrations contribute to the decline in wild rice populations when conditions allow for the reaction of sulfate to sulfide. This dissertation investigates the fate of sulfate in the rooting zone of wild rice, mechanisms and consequences of sulfide exposure to plants, and the long-term effects of sulfide exposure on population dynamics. Key findings include 1) iron plaques on root surfaces transition from iron oxide to iron sulfide during reproduction if sulfate is elevated; 2) in elevated sulfate, seed production is delayed and shortened and plants produce fewer, smaller seeds with less nitrogen; and 3) populations of wild rice grown in low sulfate have stable biomass oscillations with a period of approximately 4 years, but elevated sulfate destabilizes these cycles and drives the population toward extinction.Item Wild rice geochemistry and reproductive life stage data from experimental pots amended with sulfate, 2016(2019-10-24) LaFond-Hudson, Sophia L; Johnson, Nathan W; Pastor, John; Dewey, Brad; lafo0062@d.umn.edu; LaFond-Hudson, Sophia LWild rice, an annual aquatic plant produces fewer, smaller seeds with less nitrogen when exposed to sulfide, but does not produce decreased vegetative biomass. We compared the timing and duration of reproductive life stages in sulfate-amended plants to unamended plants to see how sulfide affects reproductive phenology. We recorded the life stage of plants starting with initiation of reproduction until senescence and measured seed count, mass and nitrogen content. Additionally, we sampled the geochemistry of porewater, sediment, and root surfaces to understand how plant life stage may control sediment redox conditions relevant to sulfide.