Browsing by Author "Miller, Michael"

Now showing 1 - 5 of 5
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    American Indian Alcoholism in St. Paul.
    (Center for Urban and Regional Affairs, University of Minnesota, 1981) Miller, Michael; Waterman-Wittstock, Laura
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    Development of Image Analysis Tools to Quantify Potato Tuber Quality Traits
    (2022-08) Miller, Michael
    Potato is the most popular non-cereal food crop and a major staple crop. Despite the importance of potato, it has seen little yield improvement through breeding over the past century when compared to other crops. One difficulty in potato breeding is the large number of quality traits that must be accounted for in order to create marketable potato varieties. These quality traits are often measured using imprecise, subjective scales. This thesis covers my work in improving the tools available for use in measuring and breeding for potato tuber quality traits. In Chapter 1, I review the literature relevant to a selection of quality traits and their measurement. I discuss machine learning and its use in identifying more intricate tuber quality traits, as well as efforts to perform genomic selection in autotetraploid potato as a possible application for highly quantitative quality trait data. Chapter 2 covers the mechanics and capabilities of the potato tuber image analysis program, TubAR. I compare the quantitative measurements provided by TubAR to human visual scores for analogous traits. In Chapter 3, I discuss efforts to expand the scope of traits able to be measured with image analysis by employing machine learning image classification, using the pressure bruise and skin finish traits.
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    Investigating net blotch resistance in Hordeum jubatum
    (2019-08) Miller, Michael
    Net blotch (Pyrenophora teres f. teres) is a major disease of barley (Hordeum vulgare). Genetic resistance in cultivated barley is mainly found in one major region of the genome, suggesting that wild relatives should be investigated to enhance the diversity of resistance in the cultivated species . This study looked at net blotch resistance in Hordeum jubatum, a member of the tertiary genepool of barley. Over 300 accessions of H. jubatum collected from 108 sites in central North America were grown in a greenhouse and tested for their reaction to pathotype Pt_1351 of P. teres f. teres. Twenty-eight differential accessions of barley were also evaluated as controls. Nine days after inoculation, plants were scored for their infection responses (IRs) on a ten-point scale. IRs were generally low, but variation was observed. The H. jubatum accessions had a mean IR of 2.9 and a range of 1 to 6.5. H. vulgare controls had mean IR of 2.5 and a range of 1 to 6. No general trend was seen with respect to IR and geographic location. The disease scores of the H. vulgare controls generally did not match expectations based on previous studies, but average infection scores similar to that of the H. jubatum in this study was seen in other studies of net blotch infection in wild Hordeum species. The lack of a trend in disease score compared to geographic location suggests that factors heavily influenced by geographic location, such as rainfall and barley cultivation, are not responsible for variation in net blotch resistance. Future studies of net blotch resistance in H. jubatum would benefit from increased replication to better assess differences between individual accessions. The variation in net blotch resistance seen in this study suggests H. jubatum may be a source of novel resistance and warrants further study into net blotch resistance in H. jubatum.
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    A novel inoculation technique for integrating the endophyte Epichloe festucae into perennial ryegrass
    (2018-11) Heineck, Garett; Ashbrenner, Brooke; Miller, Michael; Watkins, Eric
    The fungal endophyte Epichloe festucae var. Lolii is commonly associated with perennial ryegrass (Lolium perenne). Some endophytes have been shown to reduce disease severity and often produce toxic alkaloids that can be harmful to mammals and invertebrates. There is interest in incorporating novel endophytes into elite genotypic selections to improve cultivar disease resistance, reduce animal herbivory or replace an existing strain negatively impacting forage quality. The objective of this study was to test a novel inoculation technique that built upon previous methods, included different dark incubation periods and multiple endophyte strains.