Digital Commons Network^™

Climate Interactions Drive Tree Physiology And Growth In A Northeastern Forest Ecotone, Alexandra M. Barry

Electronic Theses and Dissertations

Climate change is a threat to global forest ecosystems. In the northeastern United States, forest trees are facing rising temperatures and increasingly inconsistent moisture regimes. In addition to long-term changes in climate conditions, there is concern about the potential for more frequent and intense climate extremes, which can have severe and rapid negative effects on tree physiology and growth. Further, climate extremes may co-occur to produce a greater magnitude of effect than the sum of their parts, with a prominent example being hot droughts, which are increasing in occurrence and severity. The impact of these and other extreme climate interactions …

Long-Term Influence Of Commercial Thinning On Spruce-Fir Forests, Bishnu H. Wagle Mr.

Electronic Theses and Dissertations

This study investigates long-term influences of pre-commercial thinning (PCT) and commercial thinning (CT) treatments in spruce-fir forests, a key forest type in northeastern North America. Utilizing repeated measurements from replicated experimental research sites (n=15) in Maine, both stand- and tree-level responses to contrasting CT with and without prior PCT (NoPCT) have been quantified. In addition, an in-depth economic analysis, exploring the impact of different thinning treatments, associated costs, merchantability specifications, varying timber and carbon prices, and discount rates, on net present value (NPV) has been carried out using both measured and projected data. Thinning treatments at nine PCT sites combined …

Deconstructing The Art Of Physical Weed Control, Jordan W. Parks

Electronic Theses and Dissertations

Farmers adjust physical weed control (PWC) tools to optimize efficacy based on observations of weeds, the crop, and soil conditions. These many variables make PWC research challenging. To study PWC tool settings more closely, we constructed a soil bin with a mobile tool carriage inside of a heated glasshouse. The soil bin was 2 m wide by 12 m long by 1 m high, with a tool carriage that can operate at 0.4 to 19.0 km h^-1. Tool angle, spacing, depth, and speed can all be precisely adjusted from the tool carriage and control panel. The goal of …

Influence Of Biochar As A Soil Amendment On Soil Water Content And Wild Blueberry Physiology, Abigayl Novak

Electronic Theses and Dissertations

Maine wild (or lowbush) blueberries (Vaccinium angustifolium Ait.) continue to face challenges imposed by climate change. Reduced frequency of precipitation and increased drought conditions have negatively impacted this crop since it resides in sandy soils with limited retention of water and nutrients. The wild blueberry plants growing in water- and nutrient-poor sandy soils are likely to have poor resilience to drought, resulting in a decline in berry yield during drought years. Thus, there is an urgent need to find a drought management solution for wild blueberries. Compared with other drought management practices, such as irrigation systems, mulching, and adopting drought-resistant …

Factors Affecting Apothecia Production And Primary Infection By Monilinia Vaccinii-Corymbosi On Vaccinium Angustifolium, Ian Leonard

Electronic Theses and Dissertations

Mummy berry, caused by Monilinia vaccinii-corymbosi (MVC), is a prolific disease of Vaccinium angustifolium (wild blueberry) leading to decreased yield in wild blueberry fields throughout the Downeast (DE) and Midcoast (MC) regions of Maine (ME). This study aimed to identify factors affecting primary inoculum production and infection by MVC on wild blueberry, and what bud stages of wild blueberry are most susceptible to infection. Through common garden (CGE), field and incubation experiments conducted in 2021 and 2022, factors affecting carpogenic germination of MVC pseudosclerotia and relationships between susceptible wild blueberry buds and environmental factors were analyzed. The CGE conducted in …

A Programmatic Geographic Information Systems Analysis Of Plant Hardiness Zones, Andrew Bowen

Electronic Theses and Dissertations

The Plant Hardiness Zone Map consists of thirteen geographical zones that describe whether a plant can survive based on average annual minimal temperatures. As climate change progresses, minimum temperatures in all regions are expected to change. This work programmatically evaluates predicted future climate projection data and converts it to United States Department of Agriculture-defined hardiness zones. Through the next 80 years, hardiness zones are projected to move poleward; in effect, colder zones will lose area and warmer zones will gain area globally. Some implications include changes in crop growing degree days, which could alter crop productivity, migration and settlement of …

Biotic And Abiotic Factors Contributing To The Invasion Success Of Microstegium Vimineum In Eastern Deciduous Forests., Kimberly Koenig

Electronic Theses and Dissertations

Forest managers face multiple challenges in maintaining woodland systems, including climate change, habitat destruction and fragmentation, and the invasion of novel species. Invaders can change microclimates, alter nutrient cycling and understory habitat, and outcompete native species, leading to native species population declines and reduction in species richness. To effectively combat plant invasions it is necessary to first understand factors contributing to invasive species spread, including the complex interactions between invaders and native biota. This dissertation investigates the abiotic conditions and biotic interactions associated with invasion success of the non-native grass Microstegium vimineum, which is a species of great concern …

Soil Profile Properties And Greenhouse Gas Emissions As Influenced By Long-Term Cattle Manure And Inorganic Fertilizer Applications Under Corn-Soybean-Spring Wheat Rotation In Eastern South Dakota, Anuoluwa Ojonoka Sangotayo

Electronic Theses and Dissertations

The application of manure and inorganic fertilizer in row crops may significantly influence soil and greenhouse gas (GHG) emissions. Understanding the long-term influence of these management practices on soil pore characteristics, hydro-physical properties and greenhouse gas emission is essential in developing proper conservation practices. However, there is limited information on the impact of cattle manure and inorganic fertilizer application on soil hydro-physical properties, soil pore characteristics at lower depths and surface GHGs emissions. Therefore, the objectives of this study were to; (i) utilize X-ray computed tomography (XCT) technique to quantify the impact of manure and fertilizer amendments under a corn …

Biological Control Of Bacterial Leaf Streak Of Wheat Using Antagonistic Rhizobacteria, Ashley Frederickson

Electronic Theses and Dissertations

Wheat (Triticum aestivum L.) is one of the world’s most valuable crops, and the primary food grain produced in the United States. A major disease in wheat production is Bacterial Leaf Streak (BLS) caused by the gram-negative bacterium Xanthomonas translucens pv. undulosa (Xtu). Very few management strategies are available to growers to manage this disease, as common chemicals do not provide adequate control. A number of studies have been conducted on biological control using Rhizospheric bacteria for the control of various plant diseases, but limited data is available on the efficacy of biological control using Rhizospheric bacteria for controlling Bacterial …

Tracking Nitrogen Mineralization In The Presence Of Biochar Utilizing Complementary-Method Assays In East Central South Dakota, Andrew Calvin Engel

Electronic Theses and Dissertations

Understanding soil N transformations in agricultural systems of the Northern Great Plains is crucial for guiding effective soil and nutrient management of this vital cropland. While the use of biochar in agriculture has attracted great attention recently, little has been reported on the seasonal dynamics of soil nitrogen (N) transformation and its response to biochar application. A field experiment was conducted over 2 seasons, spring (6/3/19-6/24/19) and summer (7/26/19-8/16/19), using four treatments or control soil, urea (224 kg N/ha), biochar (46,250 kg/ha), and urea+biochar (224 kg N/ha and 46,250 kg/ha, respectively). The results for both seasons showed biochar had no …

Phosphate2 And Pin-Likes7 Affect Symbiotic Nodule Phenotypes In Soybean, Bhawandeep Kaur

Electronic Theses and Dissertations

Legumes and soil rhizobia share a symbiotic relationship, wherein rhizobia fix atmospheric dinitrogen in exchange for photosynthates from the host plant. This exchange of mutual benefits occurs in a specialized root structure called ‘nodule’. Soybean (Glycine max) nodules arise from root outer cortical cells. De novo cell differentiation of cortical cells during nodule development leads to the formation of two distinct nodule zones in the mature nodule: the central infection zone where nitrogen fixation occurs and the peripheral parenchyma zone that houses vascular bundles. Plant signaling mechanisms that dictate the development of these nodule zones are not known. To address …

Methods For Improving Potassium Fertilizer Recommendations For Corn In South Dakota, Andrew J. Ahlersmeyer

Electronic Theses and Dissertations

Corn (Zea mays L.) is a vital commodity in South Dakota’s agricultural sector. Optimal corn production occurs when there are sufficient mineral nutrients in the soil, especially potassium (K). Applications of K fertilizer are used when soil test K (STK) levels are deficient. Therefore, producers need reliable, thoroughly tested fertilizer recommendations to make profitable decisions and maintain environmental stewardship. South Dakota K fertilizer recommendations have not been updated in nearly 20 years. Simultaneously, changes in corn genetics, management practices, and climate patterns suggest that the critical soil test value (CSTV) for STK may have shifted in that same time frame. …

Unveiling Race Diversity And Fungicide Sensitivity Profiles Of Pyrenophora Tritici Repentis Populations In South Dakota Collected From 2021-2023, Jaswinder Kaur

Electronic Theses and Dissertations

Tan spot, a foliar disease of wheat caused by the ascomycetes fungus Pyrenophora tritici repentis (Ptr), poses a significant threat to wheat crops globally. The disease gained economic importance in the late 1970s due to shifts in farming practices, such as minimal tillage and planting on crop residues, providing favorable conditions for the pathogen to overwinter and cause infections. Ptr is classified into eight races based on the production of necrotrophic effectors—Ptr ToxA (necrosis-inducing), Ptr ToxB, and Ptr ToxC (chlorosis-inducing on respective susceptible and sensitive cultivars)—resulting in distinct symptoms on susceptible wheat differentials. The inverse gene-for-gene hypothesis of Ptr suggests …

Addressing Soil Carbon Sequestration Response From Multispecies Dairy Forage Systems And Modeling Rangeland Beef Cow Dry Matter Intake Using Precision Enteric Emissions Measurements, Lillian J. Mcfadden

Electronic Theses and Dissertations

Regenerative agriculture is a pressing matter for the dairy industry to address cropland sustainability and carbon sequestration. One regenerative management practice that has been identified to help with row crop sustainability for key metrics like soil organic carbon (SOC) is complex covers. When producers use complex covers one of the main challenges is that it takes time to detect a change in SOC. However, simulation models are a tool that can be used to help determine if a regenerative practice is a strategy that gives the best results (i.e., increased SOC) while aligning with long-term production goals. Therefore, our objectives …

Improving The Utility Of Precision Agriculture Through Machine Learning And Climate-Smart Practices, Skye Brugler

Electronic Theses and Dissertations

Climate Smart Practices are management strategies that focus on increasing soil and crop productivity, utilize site-specific strategies to increase resiliency against the effects of climate change, and mitigate these negative effects by reducing greenhouse gas (GHG) emissions. Decision Support Systems (DSSs) using machine learning (ML) can adjust models based on new information and help farmers make climate smart decisions within their operation. The 4R nutrient management model of right source, rate, location, and time also demonstrates a framework that may be considered climate smart by improving soil and crop productivity. However, when initially conceptualized, the 4R model did not consider …

Identifying Optimum Germination Temperatures And Analysis Weights In Seed Testing For Stiff Goldenrod (Solidago Rigida) And River Bulrush (Bolboschoenus Fluviatilis), Rachel Geary

Electronic Theses and Dissertations

Federal and state seed laws require seed lots offered for sale to be tested and labeled with the appropriate information before they can be sold. Those tests are conducted in seed testing labs all around the world. In the United States, accredited seed testing labs follow the Association of Official Seed Analysts (AOSA) Rules for Testing Seeds to provide information for labeling. The rules lack instructions for weights and germination for many native species. Stiff goldenrod (Solidago rigida) and river bulrush (Bolboschoenus fluviatilis) are two species that lack any information required for testing. When seed testing labs use correct weights …

Genomics-Assisted Approaches To Improve Grain Yield And End-Use Quality In Hard Winter Wheat (Triticum Aestivum L.), Harsimardeep Singh Gill

Electronic Theses and Dissertations

Global wheat production needs to be increased by 60% to meet the future demand of feeding nine billion people by 2050. Simultaneously, it is important to improve the enduse quality to meet the requirements of producers, grain markets, processors, and consumers. Thus, the development of more productive wheat varieties with better enduse quality remains the primary focus for all wheat breeding programs. However, direct phenotypic selection for improving grain yield and end-use quality is difficult as it is highly influenced by environmental factors. This dissertation focuses on harnessing advancements in genomics applications, including genome-wide association studies (GWAS), for the genetic …

Effect Of Foliar And Preplant Sulfur Application On Soybean Nutrient Uptake, Yield, And Seed Protein And Oil Content, Gena Ram Mahato

Electronic Theses and Dissertations

In recent years, Sulfur (S) deficiency has been observed in soybean producing regions in the US and different parts of the world. The major factors behind the frequent occurrence of S deficiency are reduced atmospheric S deposition due to strict regulations on emissions from fossil fuels, large S removal from high yielding crops, less use of fertilizers containing S, and intensive cultivation practices. To test S limitations, I conducted two independent studies from 2019 to 2021 at two locations in Eastern South Dakota to determine the effect of foliar and preplant S application on soybean. The objectives of this research …

Investigating Dormancy And Germination Characteristics To Promote Restoration Success In The Northern Great Plains, Gregory A. Cooper

Electronic Theses and Dissertations

Failures in seed-based restoration can be partially attributed to a lack of knowledge on seed dormancy. Dormancy is beneficial for plant establishment in unpredictable environmental conditions, but a lack of uniform germination can hinder restoration efforts. The purpose of this research was to gain a better understanding of dormancy displayed by select forbs of the northern Great Plains. The first data chapter attempted to identify and break dormancy class. Seeds were treated with scarification, smoke, and fertilizer pretreatments in an attempt to break seed dormancy. Seeds were also placed in spring and summer temperatures to identify how seasonal phenology influenced …

Enhancing Nitrogen Use Efficiency Through Ai-Powered Image Analysis And Innovative N-Rich Spot Method, Bobby Azad

Electronic Theses and Dissertations

This study conducted in 2023 aimed to enhance nitrogen use efficiency (NUE) in wheat and corn grown in South Dakota. Based on dynamic weather conditions and other factor interactions, conventional nitrogen (N) recommendations need to be improved. Soil properties information, including electrical conductivity, was used to create management zones. In each zone, three N-rich spots were established as biosensors. Drones and satellites collected imagery data, and an AI-driven approach assessed the crop response to applied N. A dynamic N application approach, integrating aerial data with historical records, was developed and evaluated. Our methodology, at a 95% confidence level, resulted in …

Fungicide Sensitivity In P. Tritici-Repentis Diverse Population And Phenotyping Of Spelt Wheat For Multiple Diseases, Zunera Shabbir

Electronic Theses and Dissertations

Pyraclostrobin, a QoI fungicide, is extensively used in the management of fungal leaf spot diseases. In this study, 215 P. tritici-repentis isolates collected from wheat fields in South Dakota were evaluated for their sensitivity to Pyraclostrobin. Of 215 isolates, 48 isolates (22%) exhibited insensitivity based on G143A mutation and EC50 values using spore germination assay. Our results indicate reduced sensitivity to insensitivity to pyraclostrobin in some isolates suggesting regular monitoring of the P. tritici-repentis population to QoI fungicides is essential to track the evolution of insensitive population. Spelt wheat (Triticum spelta L.) is an ancient cereal that is gaining small …

The Effects Of Residue Amounts And Variety Selection On The Development Of Wheat Fungal Pathogens In South Dakota, Abrielle Tembreull

Electronic Theses and Dissertations

Roughly 50% of South Dakota cropland is under the practice of no-till, with large increases in acres of no-till in the last 20 or so years. No-till is beneficial for Great Plains states, such as South Dakota, as soil residues are withheld. Residues are shown to increase soil health through retention of moisture and increase of microorganisms, but residues can serve as a source of inoculum for fungal pathogens that can overwinter on them. As wheat is one of the most important food crops in the world, it is important to protect this vital crop from diseases. Diseases of wheat …

Fusarium Head Blight Resistance Assessment In Barley, Tasneem Fathima

Electronic Theses and Dissertations

Fusarium head blight (FHB), commonly called scab is the most devastating disease of wheat and barley caused by the ascomycete fungus, Fusarium graminearum. FHB affects both the quality and quantity of cereal grains affecting the supply chain of the food and feed industry and the marketability of the produce. Barley (Hordeum vulgare L.) is among the several crop species most vulnerable to FHB infection. An estimated 25% of Spring barley grain production in the United States is used to make malted beverages such as beer. Malting barley is a relatively high-value crop with high demands regarding grain quality. FHB directly …

Expanding The Use Of High-Performance Liquid Chromatography For Varietal Identification Or Verification Of Selected Cereal Crops, Johnna Jorgensen

Electronic Theses and Dissertations

High-performance liquid chromatography (HPLC) is a form of analytical chemistry where adsorption is a key factor in which the purpose is to separate, identify and quantify each component in a mixture. It is the optimal separation technique of chemical and biological compounds that are non-volatile including proteins and natural products (i.e., plant extracts). As each sample component interacts differently with the absorbent material within the column, the flow rates change leading to the separation of peaks, which are plotted via computer software. Most commonly HPLC analysis has been used for chemical manufacturing and pharmaceutical purposes. When using HPLC for crop …

Middle Savannah River: An A/R/Tographic Ecopedagogical Ethnography Experimenting With Rhizomatic Perspectives, Lisa Augustine-Chizmar

Electronic Theses and Dissertations

This research is an experiment in perspective. Using the four commonplaces (Schwab, 1978), I practiced letting the Savannah River teach me what there is to know about the water, the land, the people, and the other entities that depend on ki through artistic, ethnographic, and ecopedagogical lenses. The ethnographic findings describe the social actors that depend on ki and give a voice to the River. The a/r/tographic findings display the River on a canvas map through two hundred years using paint, clay, photography, video, abstract acrylics, and fabric. Together, these methods contribute to a unique ecopedagogical journey. This word cloud …

Developing Best Practices For The Propagation Of Spartina Alterniflora For Use In Salt Marsh Restortaion, Justin Hinson

Electronic Theses and Dissertations

Coastal salt marshes are valuable ecosystems under threat from climate change and sea level rise. Living shorelines offer a promising solution, often incorporating the foundational salt marsh species Spartina alterniflora due to its ability to tolerate natural stressors and maintain sediment stability. However, research suggests that seed-based propagation protocols should be developed on a local scale due to the genetic heterogeneity within and between S. alterniflora populations. Here, we attempt to contribute to the development of one such protocol for coastal Georgia S. alterniflora.

In Fall 2021, seeds were collected bi-monthly from four marshes of varying ocean proximity and …

Improving Use Of Soil Health Practices In Kansas: A Study Of Barriers To Adoption And Novel Incentive Programs, Sara Kelemen

Electronic Theses and Dissertations

As climate change continues to affect agroecosystems, farm resilience will become increasingly important. To feed a growing global population, the future of agriculture must be secure and ultimately, sustainable. Use of soil health practices can increase farm resilience through improved provision of ecosystem services. Not only does this benefit the farm agroecosystem, it can also improve also agronomic outcomes while also improving landscape scale ecological conditions. It can also can have positive impacts on profitability. The benefits to use of soil health practices are well documented, yet rates of adoption in the United States remain relatively low. Therefore, research must …

Genetic Characterization Of Centromere-Mediated Uniparental Genome Elimination In Arabidopsis, Diana Spencer

Electronic Theses and Dissertations

The production of haploids through crossing was first discovered from instances of interspecies crosses in Nicotiana spp. in 1924. Since then, haploid induction crosses has been used to improve plant breeding programs and commercially utilized in a number of crop industries. The generation of doubled haploid instantaneously creates a pure homozygous line, therefore eliminating the need for several generations of inbreeding. There are several pathways to induce haploids in plants: of these methods, centromere-mediated genome elimination pathway engenders the highest haploid induction rate (HIR) with up to 45% in Arabidopsis compared to 15% through phospholipase-mediated haploid induction in maize. Centromere-mediated …

A Sky Island Perspective: New England Alpine Plant Distributions Across The Region, Andrea Tirrell

Electronic Theses and Dissertations

Alpine ecosystems around the globe are at risk due to climate change, human disturbance, and habitat loss. New England alpine zones are small and fragmented, which could make them vulnerable to global change. However, the persistence of tundra relics throughout the Holocene suggests the persistence of these communities in microclimate refugia. Assessing the near-term vulnerability of alpine plant communities is challenged by a lack of standardized, repeat surveys and long-term monitoring data, which presents a challenge for the many agencies monitoring New England’s alpine zones. Island biogeography theory predicts that alpine species richness is a function of area, but this …

Distribution And Soil Characteristics Associated With The Neches River Rose-Mallow (Hibiscus Dasycalyx), Morgan E. Langlinais

Electronic Theses and Dissertations

The Neches River rose-mallow, Hibiscus dasycalyx, is a rare herbaceous perennial endemic to East Texas. The threatened, obligate wetland species is currently at risk of being lost in the wild due to habitat loss, encroachment of nonnative and native plant species, and hybridization with two other Hibiscus congeners, Hibiscus laevis and Hibiscus moscheutos. Known locations of each of the three Hibiscus species were used to measure select soil characteristics and habitat variables associated with each of the rose-mallows. H. dasycalyx was concluded to be associated with more fertile soils and slightly more canopy coverage than H. laevis and …