Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Consider the roots: examining barley belowground in the search for adaptation(Montana State University - Bozeman, College of Agriculture, 2024) Williams, Jessica Lynn; Chairperson, Graduate Committee: Jamie Sherman; This is a manuscript style paper that includes co-authored chapters.Barley is important for global food security and sustaining the economically valuable malt industry. Montana is a top barley producer in the United States, but terminal drought stress poses a significant threat to this production by negatively impacting yield and quality. New crop varieties with enhanced environmental adaptation and soil resource extraction would help address this and other issues facing modern agriculture. Stay-green is a trait that extends grain fill in cereals and can stabilize yield and quality under drought. However, this trait and its benefits can be inconsistent across environments and its successful incorporation into breeding strategies would benefit from expanded understanding of stay-green. Roots may play a role in stay-green physiology. Roots provide plants with the water and nutrients needed for growth and are important for crop performance in their own right. Different root system architectures provide adaptation to different environmental stressors, but studying these belowground structures is challenging. Adaptation is also impacted by soil properties and microbial communities. For this dissertation, roots were examined in greenhouse seedling assays and field trials in Montana. Agronomic performance was also assessed for malt barley and spring wheat cultivars varying for stay-green, a biparental barley population segregating for stay-green, and a diverse mapping population of barley lines from different breeding programs. Stay-green cultivars had a greater percentage of deep roots, more prolonged root growth during grain fill, and greater yield. Analysis of the biparental population identified genetic co-segregations of stay-green, root phenotypes, grain quality, and quality stability between environments, further supporting the benefit of stay-green in dry environments and its connection to roots. The diverse mapping population was used to find associations between the relative abundances of bacteria in the rhizosphere and barley genetic loci, that were mostly environment specific. Rhizospheric bacteria may be involved in local adaptation of plants. Finding plant genetic signal for these microbial characteristics supports the idea that it may be possible to breed crops with enhanced ability to recruit beneficial microbiomes if environmental influence and agronomic impact can be understood. Root examination remains a challenging but worthwhile avenue to pursue in crop adaptation research.Item Comparing juvenile physiology and morphology of two high-elevation pines, Pinus albicaulis and Pinus balfouriana(Montana State University - Bozeman, College of Letters & Science, 2023) Sparks, Katherine Elizabeth; Chairperson, Graduate Committee: Danielle UlrichWhitebark pine (Pinus albicaulis, PIAL) and foxtail pine (P. balfouriana, PIBA) are slow-growing, high-elevation, five needled ("high five") white pines and are foundation and keystone species in alpine and subalpine environments, providing essential resources and habitat for many species including the Clark's nutcracker and grizzly bears. In recent years, PIAL has experienced significant decline due to an amalgamation of climate change, white pine blister rust, and mountain pine beetle. As a result, PIAL is listed as endangered under the Canadian Species at Risk Act and threatened under the United States Endangered Species Act. Conversely, PIBA has experienced minimal decline. PIBA also exists in two disjunct populations, one in southern California (PIBAS) and one in northern California (PIBA N), resulting in the species being split into two sub-species (P. balfouriana subsp. austrina and balfouriana). Our study compared the physiology and morphology of the two species (PIAL and PIBA) and the two foxtail populations (PIBA N and PIBAS) to better understand how they interact with and respond to abiotic and biotic stressors in their high-elevation environments. We grew four-year-old PIAL and PIBA juveniles in a common greenhouse environment. In total, we measured 159 traits describing their morphology, biomass, stomata, xylem, budburst phenology, physiology, whole plant Volatile Organic Compounds (wpVOCs), phloem volatile resin (PVR) compounds, and Non-Structural Carbohydrates (NSCs). We found that PIAL and PIBA displayed different suites of traits that enable them to persist in their high elevation habitats, characterized by similar abiotic stressors (cold temperatures, high winds, summer drought) and biotic stressors (white pine blister rust, bark beetle). The two foxtail populations were similar for most traits except for wpVOC concentration and composition where PIBAS had significantly higher wpVOC concentration than PIBA N. For most traits, PIAL was most similar to PIBA N and differed the most with PIBAS while PIBA N was the intermediate being more similar to both groups, especially in wpVOC composition and concentration.Item Determinants of participation and coverage level choices in the pasture, rangeland and forage insurance program(Montana State University - Bozeman, College of Agriculture, 2020) DelCurto, Molly Jo; Chairperson, Graduate Committee: Eric BelascoDrought risk has become a primary concern for ranchers as a drought can cause substantial financial losses and have been occurring with more regularity and severity than in years past. The Pasture, Rangeland, and Forage (PRF) insurance program allows ranchers to insure their livestock grazing land against potential losses from low rainfall conditions. This program has undergone substantial changes in its availability and premium prices. We implement a linear fixed effect regression model to estimate changes in participation and coverage level choices in response to changes in factors affecting premium payments. Additionally, we analyze the impacts of future prices, previous year's earnings, and the Livestock Forage Disaster Program (LFP) on participation and coverage level choices. Our results show that increasing county base values (CBVs) has a significant negative impact on participation, suggesting the more costly the premium payment, the lower the participation. Additionally, we find evidence of memory anchoring and rational decision making in the purchasing decisions of participants. Overall, we find preliminary evidence that ranchers display demand sensitivity to changes in CBVs as well as evidence that producers follow expected utility theory in choosing the highest coverage levels, especially when coverage levels have the same subsidy rate.