Browsing by Subject "seed production"
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Item Association between Inflorescence Morphology and Seed Shattering in Perennial Ryegrass (Lolium perenne L.)(2020) Barreto Ortiz, Joan; Watkins, Eric; Ehlke, NancyThe objective of this preliminary study was to develop and implement an imaging system to explore the association between seed shattering and spike architecture. We found a significant association between spike morphology and seed shattering.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 CO2, nitrogen, and diversity differentially affect seed production of prairie plants(2009) Hillerislambers, J; Harpole, W S; Schnitzer, S; Tilman, D; Reich, Peter BPlant species composition and diversity is often influenced by early life history stages; thus, global change could dramatically affect plant community structure by altering seed production. Unfortunately, plant reproductive responses to global change are rarely studied in field settings, making it difficult to assess this possibility. To address this issue, we quantified the effects of elevated CO2, nitrogen deposition, and declining diversity on inflorescence production and inflorescence mass of 11 perennial grassland species in central Minnesota, USA. We analyzed these data to ask whether (1) global change differentially affects seed production of co-occurring species; (2) seed production responses to global change are similar for species within the same functional group (defined by ecophysiology and growth form); and (3) seed production responses to global change match productivity responses. We found that, on average, allocation to seed production decreased under elevated CO2, although individual species responses were rarely significant due to low power (CO2 treatment df = 2). The effects of nitrogen deposition on seed production were similar within functional groups: C4 grasses tended to increase while C3 grasses tended to decrease allocation to seed production. Responses to nitrogen deposition were negatively correlated to productivity responses, suggesting a trade-off. Allocation to seed production of some species responded to a diversity gradient, but responses were uncorrelated to productivity responses and not similar within functional groups. Presumably, species richness has complex effects on the biotic and abiotic variables that influence seed production. In total, our results suggest that seed production of co-occurring species will be altered by global change, which may affect plant communities in unpredictable ways. Although functional groups could be used to generalize seed production responses to nitrogen deposition in Minnesota prairies, we caution against relying on them for predictive purposes without a mechanistic understanding of how resource availability and biotic interactions affect seed production.Item Effect of Alternative Management Practices and the Fungal Endophyte (Epichloë festucae var. lolii) on Improving the Longevity of Perennial Ryegrass (Lolium perenne L.) in Minnesota(2016-12) Heineck, GarettOne of the primary challenges facing the perennial ryegrass seed producers in Minnesota is a lack of perenniality in the species when grown for seed. The first research project explored alternative management options, including fall residue management strategies and plant growth regulator applications, for multi-year seed production of perennial ryegrass. Our findings suggest that fall residue management, including both field burning and mechanical residue removal, was critical to maintaining seed yield. A second research project studied the effect of the fungal endophyte Epichloë festucae var. lolii on the freezing tolerance of a wide array of perennial ryegrass germplasm. Our results showed no direct effect of endophyte on freezing tolerance of perennial ryegrass; however, there was consistent association between the endophyte and a freezing tolerant host.