Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
13 results
Search Results
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.Item Understanding rancher's beliefs and behaviors regarding drought and natural water storage in southwest Montana(Montana State University - Bozeman, College of Letters & Science, 2018) Moore, Megan Alison; Chairperson, Graduate Committee: Jamie McEvoyDrought has the potential to impact both natural environments and human communities, with specific repercussions for agricultural communities. In the face of changes to the quality, quantity, and timing of water runoff, water storage for drought mitigation is one of the top concerns for many water managers and water users. Due to a growing recognition of negative social and environmental impacts of traditional infrastructure, such as dams, there is a need for alternative forms of water storage. The concept of nature-based solutions, specifically natural water storage systems, has gained traction as a potential strategy to slow spring runoff, store water, and raise water tables, often resulting in an increase in late season streamflows. This research examines the adoption of these new strategies, specifically flood irrigation and beaver mimicry projects in the context of a changing climate in Montana. This thesis uses the theory of planned behavior to better understand findings from twenty-two amenity and traditional ranchers in the Red Rock Watershed/Upper Beaverhead Watershed in southwestern Montana. Results show that ranchers' beliefs toward drought can impact their drought planning responses. In this watershed, it is impractical for ranchers to convert to flood irrigation due its high labor needs and low production outputs. There is potential for beaver mimicry projects to be adopted, but economic and regulatory hurdles must first be addressed. Results suggest that natural water storage practices will be more successful if organizations involved form better relationships with ranchers, remain flexible, and integrate local knowledge into decisions and policies.Item Impacts of low summer streamflows on water resources in the Jefferson Valley : historical responses and future challenges(Montana State University - Bozeman, College of Letters & Science, 2016) Leone, Alex Michael; Chairperson, Graduate Committee: Julia Hobson HaggertyIn an attempt to understand the complex interrelationships between climate, water infrastructure regimes, and water governance this thesis examines relationships between drought and water use in the Jefferson River Basin in southwest Montana. The Jefferson River is one of the three great headwater streams of the Missouri River and is itself comprised of the Beaverhead, Big Hole and Ruby Rivers, encompassing a substantial drainage basin of 9,532 sq. miles. The Jefferson's unique hydrological position inherently situates the basin "at the end of the line" of water users and flows at its confluence have plummeted to 200 cubic feet per second (cfs) during extreme drought periods, leaving little water in the river to appease appropriators along the river's remaining 80 miles. The Jefferson River (and all of its important tributaries) is highly utilized for agriculture, resulting in chronic dewatering during peak irrigation demand (typically July through mid-September). Persistent water scarcities over the last 15 years have tested the Basin's ability to sustain historic levels of agricultural production and maintain a commercial sports fishery. This thesis provides a resilience assessment of water resources in Jefferson Basin. RA's attempt to conceptualize dynamic interactions between linked social and ecological systems (SES's). Analysis of complex human use systems (SES's) is inherently interdisciplinary and necessitates a mixed methods approach. The RA completed for this thesis integrated physical analyses of the water use system (utilizing GIS, hydrology, climate and demographic data) with a qualitative survey of water stakeholders with the goal of understanding the processes that drive the Jefferson SES and identifying weaknesses that reduce resilience. Over the last 30 years the Jefferson Basin has benefited from a unique subset of water users and natural resource managers that have successfully worked to improve conditions in the face of extreme environmental challenges. This RA found that although it is highly likely that the Jefferson will be challenged by extreme conditions in the future (related to a changing climate), it is also evident that there is potential for the basin to transition into alternate and more resilient regimes.Item Tiller dynamics of blue grama and western wheatgrass subjected to drought and grazing(Montana State University - Bozeman, College of Agriculture, 1996) Eneboe, Erik JasonItem An evaluation of plant drought stress parameters in spring wheat(Montana State University - Bozeman, College of Agriculture, 1987) Touray, Katim SeringeItem Beef cattle management decisions relating to drought in the Northern Great Plains(Montana State University - Bozeman, College of Agriculture, 2002) Kruse, Rosanne EItem An analysis of droughts in the Northeast District of Montana : their features, impact, monitoring and prediction(Montana State University - Bozeman, College of Agriculture, 1992) Hershenhorn, RayaItem Restoring native plant and arthropod communities in gulf coastal prairies following plant invasion and drought(Montana State University - Bozeman, College of Letters & Science, 2014) Mitchell, Adam Benjamin; Chairperson, Graduate Committee: Andrea Litt; Andrea R. Litt, Anthony D. Falk and Forrest S. Smith were co-authors of the article, 'Shifts in composition of plant and arthropod communities following plant invasion and drought' submitted to the journal 'Restoration ecology' which is contained within this thesis.; Andrea R. Litt, Anthony D. Falk and Forrest S. Smith were co-authors of the article, 'Modifying soil properties to restore native plant communities following plant invasion and drought' submitted to the journal 'Restoration ecology' which is contained within this thesis.; Andrea R. Litt, Anthony D. Falk and Forrest S. Smith were co-authors of the article, 'Soil modification to restore native arthropod communities impacted by plant invasion and drought' submitted to the journal ''Restoration ecology' which is contained within this thesis.Plant invasions are a threat to biodiversity, as changes in plant community characteristics resulting from invasion can affect other organisms, such as arthropods. The effects of invasions may interact with other disturbances and alter the efficacy of restoration strategies. We sought to understand the effects of Old World bluestem grasses (OWBs, Bothriochloa, Dichanthium spp.), which have become dominant in prairie ecosystems and reduce the quality of habitat for wildlife. In an attempt to reduce OWBs, we applied treatments to modify soil conditions to a state which favors native plants and arthropods. We conducted our research in 2011, which coincided with extreme drought and provided us with the opportunity to test the efficacy of soil modification under varying conditions. First, we explored the effects of plant invasion and drought on native plant and arthropod communities by comparing characteristics of plots dominated by native plants to plots dominated by OWBs. As drought subsided, we observed a shift from an arthropod community driven by detritivores to one driven by herbivores associated with plant invasion. Arthropod communities were dominated by invasive species. Second, we explored the efficacy of soil modification and seeding treatments to reduce OWBs in the presence and absence of drought based on a field experiment and a more controlled microcosm experiment. Although changes in soil chemistry from soil treatments were short-lived, we observed reduced dominance of OWBs in areas treated with soil disturbance and seeding in both experiments and we observed no differences between experiments when we alleviated the effects of drought. Finally, we examined the concomitant effects of our soil modification and seeding treatments on arthropod communities in the field experiment. We observed fewer arthropods in treated plots than undisturbed OWB monocultures, but soil and seeding treatments increased arthropod diversity and reduced dominance of invasive arthropods relative to undisturbed OWB monocultures. Based on our findings, simple soil disturbance in combination with seeding of native plants may increase diversity of native plants and arthropods where invasive plants are dominant in the short term, but monitoring over longer time frames may reveal additional benefits from soil modification.