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Browsing by Author "Sterle, David, author"

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    Addressing the threat of frost damage on peach floral buds through large-scale cold hardiness phenotyping, dynamic weather modeling and non-targeted metabolomic and proteomic analysis
    (Colorado State University. Libraries, 2023) Sterle, David, author; Minas, Ioannis, advisor; Sharp, Julia, committee member; Prenni, Jessica, committee member; Caspari, Horst, committee member
    Cold damage to reproductive tissues is the greatest threat to the profitability of peach (Prunus persica) growers worldwide. Cold hardiness is the extent to which peach floral buds super-freeze without suffering lethal damage. Although no changes are visible externally to floral buds for much of the dormant season, cold hardiness fluctuates as they acclimate, deacclimate and respond to abiotic stressors such as temperature or drought. A greater understanding of the mechanisms involved in these fluctuations involves accurate and frequent measurement of the extent to which cold hardiness is changing, and the ambient weather factors influencing the changes, at different stages of the dormant season. Warmer or more erratic temperature changes during the dormant season threatens peach floral buds to more frequently receive frost damage if cold hardiness becomes misaligned with the timing of lethally cold weather events. Statistical analysis of the trends and forces impacting the cold hardiness of floral buds can help identify significant patterns. These patterns can be used to better understand the physiological mechanisms affecting cold hardiness changes, and they can be used to help predict the impact of weather conditions on cold hardiness. In addition to their use in a practical sense by growers to aid in frost management decisions, accurate cold hardiness prediction models can be used to estimate what effects foreseeable climate effects can have on the outlook of future peach production. Metabolic changes are known to occur in dormant plants, although the effects of the metabolome in peaches on cold hardiness are unknown. Changes associated with cold hardiness likely follow several trends. One such trend is the fluctuations of metabolic abundances across the season, which are more associated with the endodormancy, and ecodormancy phases and the prebloom phase. These trends likely take place every dormant season as buds undergo a steady process of acclimating and deacclimating. Another trend is the response floral buds exhibit in response to acute cold events, in order to rapidly increase cold hardiness. The study of this response necessitates the monitoring of cold hardiness as well as the metabolic shift to the weather event. The response can be further elucidated by comparing cold hardiness and metabolic changes between genotypes that have different cold hardiness phenotypes. By exploring changes a cold hardy genotype undergoes, geneticists may be able to target certain metabolic expressions that may increase the frost tolerance of future cultivars. Since frost damage can be so destructive to peach production, it is necessary to understand the risks to the peach industry moving forward surrounding climate change, and it is also necessary to understand the extent to which frost tolerance can be improved in future cultivars. This study uses a multifaceted approach to cold hardiness which involves improved and large-scale cold hardiness phenotyping using differential thermal analysis, dynamic weather prediction models and associated metabolic regulation understanding.
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    ItemOpen Access
    Evaluation of cyanobacterial biofertilizer as a supplemental or solitary fertilizer on peach yields, leaf tissue nutrient concentration, and trunk growth
    (Colorado State University. Libraries, 2016) Sterle, David, author; Davis, Jessica G., advisor; Caspari, Horst, committee member; Fonte, Steven, committee member
    Nitrogen (N) is the nutrient applied in the greatest quantities to peach trees and is a necessary component of proteins. As a result, carbon assimilation is dependent upon adequate levels of N in leaf tissue. Cyanobacteria are a type of bacteria which can fix gaseous N from the atmosphere enzymatically. This N fixation can be exploited in a cyanobacterial biofertilizer (cyano-fertilizer) production raceway, which allows farmers to grow their own source of N with relatively small energy inputs. Cyano-fertilizer was grown on three peach farms in Western Colorado, and applied to peach orchards in combination with a chicken feather meal (mixed with meat and bone meal), a dried chicken manure, and separately in comparison to a conventional foliar fertilizer, fish emulsion fertilizer foliarly applied, and a soil application of fish emulsion fertilizer. Treatments were assigned to experimental units across three separate farms (Farms A, B, and C) and arranged using Randomized Complete Block Designs. Peach fruit yield, trunk cross sectional area, leaf tissue nutrient concentrations, soil nutrient concentrations, SPAD and fruit juice quality characteristics were measured. A significant fruit yield increase was seen on Farm B in treatments which included cyano-fertilizer and manure (Cyano-Manure), versus manure alone (No-Cyano). Trunk cross sectional area showed less growth in treatments including cyanobacteria on Farm B. Significantly higher leaf tissue S, P, and Cu concentrations were found in Cyano-Manure treatments on Farm B; however, significantly greater Ca concentrations were found in the No-Cyano treatment. Chlorosis was present throughout Farm B and so relative leaf chlorophyll content was estimated by measuring Soil Plant Analysis Development (SPAD). SPAD readings were positively correlated with leaf Fe concentration. In the 2015 fertilization section, SPAD readings were higher in Cyano-Manure treatments despite the relatively low amount of Fe present in the cyano-fertilizer, suggesting that cyano-fertilizer may have increased Fe uptake by the trees. Significant differences in leaf micronutrient concentrations were found among treatments in Farm C. Across all farms, treatment effects were masked by three unforeseen events. First, a large infestation of aphids on Farm A caused the death of young vegetative tissue and also killed young peach fruit. Second, a freezing event during bloom, killed most of the fruit on two of the farms. Lastly, there were prior fertilizations earlier in the season on Farm C which lowered the impact additional fertilizer had on the trees.