Browsing by Author "Holm, David, advisor"
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Item Open Access Color, carotenoid content and sensory perceptions in potato germplasm from the Colorado Potato Breeding and Selection Program(Colorado State University. Libraries, 2014) Larson, Katie Mae, author; Holm, David, advisor; Jayanty, Sastry, advisor; Reddivari, Lavanya, committee member; Brick, Mark, committee memberField-grown potato tubers were evaluated for tuber flesh color, focusing on hue and chroma, total carotenoid content and identification and quantification of individual carotenoids. A total of 138 clones/cultivars from the Colorado Potato Breeding and Selection Program were evaluated to determine the chroma and hue of the tuber flesh. A subset of 100 entries, 65 tetraploids and 35 diploids, were analyzed for total carotenoid content and eight select entries for individual carotenoid content. Volatile flavor compounds were analyzed in 12 select entries, including two diploid entries with high carotenoid levels, using both microwaved and steamed cooking methods. Five entries from the volatile compound analysis were selected for a sensory evaluation. The relationship between tuber flesh chroma and carotenoid content was analyzed. Total carotenoid content was positively correlated (r = 0.72) with chroma for the subset of 100 entries. The range in total carotenoid content was 16 to 2741 μg/100 gfw (grams fresh weight). Diploid entries had a total carotenoid content three times higher than tetraploid entries. There was a significant entry by year interaction for total carotenoid content. Lutein was the major carotenoid detected among the eight entries analyzed. For the volatile flavor compounds, limonene was quantified and alpha-copaene, decanal, isovaleraldehyde, and 2-pentanone were detected in 12 select entries. The relationship between volatile compounds and sensory scores was analyzed. Limonene was not detected in the two diploid entries with high carotenoid levels. The sensory evaluation revealed higher sensory scores for the three tetraploid entries than the two diploid entries with high carotenoid levels. The recently named cultivar Masquerade received the highest score for overall acceptability for both steamed and microwaved cooking methods. The use of diploid potato entries will be a target for future breeding efforts in order to increase carotenoid levels. Further research is needed to identify entries with promising flavor characteristics in order to develop cultivars with greater carotenoid levels and enhanced flavor.Item Open Access Heritability estimates, accession evaluation, and digital imaging in Distichlis spicata(Colorado State University. Libraries, 2009) Christensen, Dana K., author; Koski, Anthony, advisor; Holm, David, advisorConserving water in the landscape is critical to inhabiting the arid portions of the western United States. Native accessions of the inland form of saltgrass [Distichlis spicata var stricta (Torr.) Beetle] remained green, while turfgrass lines of blue grama, buffalograss, crested wheatgrass, and bermudagrass went dormant from lack of rainfall during the drought of 2000 and 2001 in Colorado. Since saltgrass is non-domesticated, this research selected plants for four traits needing improvement to make saltgrass more turf like. Resistance to leaf rust (Puccinia aristidae Tracy), short height, high shoot density, and high seed yield were traits that made up a selection index which ranked all 158 accessions collected from the Front Range of Colorado, the Great Basin, South Dakota, and Nebraska. The top 14 females and 12 males of these were topcrossed, and progenies were evaluated. Response to selection was recorded for all four traits. Realized heritability, narrow sense heritability from half-sib analysis, narrow sense heritability from parent-offspring regression, and broad sense heritability were very high for height and shoot density. Broad sense heritability and narrow sense heritability from half-sib analysis were high for seed yield, but narrow sense heritability from parent-offspring regression and realized heritability were moderate. A major gene for rust resistance was inferred. Negative heterosis measured on the midparent for height and seed yield were noted. Positive heterosis occurred for shoot density.Item Open Access Potato tuber yield, quality, mineral nutrient concentration, soil health and soil food web in conventional and organic potato systems(Colorado State University. Libraries, 2015) Kammlade, Sara Marie, author; Holm, David, advisor; Essah, Samuel, advisor; Stromberger, Mary, committee memberTo view the abstract, please see the full text of the document.