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Bioregenerative Dietary Supplementation: Optimizing Brassica Production For Space Travel Through Light Intensity, Photoperiod, And Harvest Methodology, Ethan W. Darby
Masters Theses
Bioregenerative dietary supplementation, a component of bioregenerative life support, will be necessary for the success of future exploration-length space endeavors. Plants, as autotrophic producers of calories, nutrients, and oxygen, will be indispensable in the development of these systems. Previous work has identified leafy greens from the genus Brassica as promising candidates for in-flight production of necessary human nutrients such as vitamins C, B1, and K1, in addition to β-carotene, the primary vitamin A precursor in the human diet. These plants also produce lutein and zeaxanthin, two compounds important in protecting the eye from radiation-induced damage, as …
A Robust Agroinfiltration Method, Bryce N. Trull
A Robust Agroinfiltration Method, Bryce N. Trull
Masters Theses
Stable transformation of soybean (Glycine max) is a markedly slow and laborious process. Thus, a tool that enables rapid evaluation of genetic elements in planta is critical to advance complex research and genetic engineering in soybean. To that end, a substantially robust agroinfiltration method was innovated in this work. Agroinfiltration is a technique that leverages Agrobacterium-mediated transient transformation to deliver genetic elements to the cells of whole plant tissues, usually leaves. Several factors were found to be relevant to successful soybean leaf agroinfiltration, including genotype, surfactant, developmental stage, and Agrobacterium culture medium. The research represents not only …
Establishing And Optimization Of Tissue Culture Work With Erigeron Canadensis, Robert Petursson
Establishing And Optimization Of Tissue Culture Work With Erigeron Canadensis, Robert Petursson
Masters Theses
Glyphosate resistance among weed species has been an increasing problem in crop production over the past two decades. Glyphosate resistant Erigeron canadensis (horseweed) has been found on multiple continents and 20 U.S. states. It appears that the resistance is of non-target type, with mechanisms of action that have yet to be elucidated at the gene level. For the first portion of the study, I focused on reproducing the original indirect organogenesis protocol but discovered biotype variability can influence regeneration success. An improved indirect organogenesis method was then developed using the previously published methods that could be used across biotypes. A …
Nature As Material, Time As Tool, Chuchu Chen
Nature As Material, Time As Tool, Chuchu Chen
Masters Theses
No building stands forever. Over time, the natural environment acts upon the outer surface of the building, leading to the failure of materials and the final dissolution of the structure itself, leading to ruin. In order to prevent this or retard its occurrence, we constantly maintain and renew the things we build. Nature seems to stand in opposition to architecture. The passage of time is constantly subtracting from the building. However, what differentiates nature from architecture? This thesis questions whether these two are not opposed, but on a continuous spectrum. Approaching the building as part of the overall environment that …
Reintroducing Hemp (Rongony) In The Material Palette Of Madagascar: A Study On The Potential Of Hemp Clay Components And Its Impact On Social And Ecological Communities., Henintsoa Thierry Andrianambinina
Reintroducing Hemp (Rongony) In The Material Palette Of Madagascar: A Study On The Potential Of Hemp Clay Components And Its Impact On Social And Ecological Communities., Henintsoa Thierry Andrianambinina
Masters Theses
When mentioning the word hemp, especially in the local language of Madagascar, the literal translation does not set it apart from marijuana, as they are both called “rongony” - creating the stigma around hemp as the negative stereotype of marijuana. However, the material has been used by the ancestors of Madagascar, as well as across cultures, in its fibrous form to produce fabrication like textile goods and packaging. During colonization, the prohibition of hemp intensified, and since then, any activity related to either of these plants is prohibited and will end in severe punitive measures. This thesis explores the strengths …
Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer
Impact Of Cover Crop Species Diversity On Soil Nutrient Availability And Crop Productivity, Amanda Kramer
Masters Theses
Cover crops provide multiple environmental benefits that improve both soil and water quality; however, farmers only utilize them on approximately 5% of harvested U.S. cropland. Low adoption rates are attributed to yield impact concerns, seed and planting costs, and lack of advocacy. This study, which began in October 2019, assessed the effects of nitrogen rate and cover crop diversity on weed biomass, soil coverage, in-situ residue decomposition, soil nitrogen and phosphorus availability, and cash crop yield to better understand the costs and benefits of cover crop adoption at two locations in Tennessee (Milan and Spring Hill). Treatments were replicated 4 …
The Use Of Biological Soil Health Indicators To Quantify The Benefits Of Cover Crops, Alexander Wu
The Use Of Biological Soil Health Indicators To Quantify The Benefits Of Cover Crops, Alexander Wu
Masters Theses
Soils provide many essential functions that support the world. With a decline in soil health, these functions also decrease in efficiency, and can threaten the health of billions of people around the world. Typically, soil health tests do not use biological indicators, however microbes drive and perform vital functions to increase soil health. One way to increase soil health is through the use of cover crops to reduce soil erosion during fallow periods, increasing soil organic matter, as well as collecting nutrients from soil into their biomass. These cover crops are then terminated through various methods such as herbicides, disk …
The Effects Of Deleting Lrb E3 Ligase Region 2 On Red Light Responses In Arabidopsis Thaliana, Sabina Liskey
The Effects Of Deleting Lrb E3 Ligase Region 2 On Red Light Responses In Arabidopsis Thaliana, Sabina Liskey
Masters Theses
The ability of plants to absorb light through photoreceptors is essential for successful plant development. Phytochromes are important plant photoreceptors that detect and absorb red and far-red light and must function properly for plant survival. The Light Response BTB proteins (LRB) play an important role in a plant’s response to red light by degrading phytochrome B (PhyB) via the ubiquitin proteasome system (UPS). Although there has been a successful investigation into understanding the function of the LRBs, the function of a few regions within LRB proteins remains unknown, including a portion located on the N-terminal end of the protein, termed …
Assessing Warm-Season Annual Grasses To Increase Forage Inventory, Andrea Marroquin
Assessing Warm-Season Annual Grasses To Increase Forage Inventory, Andrea Marroquin
Masters Theses
Summers are expected to continue to increase in heat/dryness in the Northeast, causing issues pertaining to forage production during the summer to worsen. Many pastures grow cool season grasses, even during the summer. These grasses enter a dormant period and slowdown in production during the months of July and August, leading to what is referred to as “summer slump”. Some farms grow corn silage during the summer, and while corn silage is a valuable crop, its cultivation often does not support soil biology. This research addresses solutions for both summer slump foraging and more sustainable silage. Summer annuals grow more …
Evaluation Of Semiochemicals For Attractiveness To Multiple Tortricid (Lepidoptera) Pests In Apple Orchards, Ajay P. Giri
Evaluation Of Semiochemicals For Attractiveness To Multiple Tortricid (Lepidoptera) Pests In Apple Orchards, Ajay P. Giri
Masters Theses
Tortricid moths (Lepidoptera) are known for their outstanding olfaction capabilities that allow them to detect, process, and respond to chemical information emitted by host or non-host plants. Such an ability to filter out odors from the complex mixture to locate their host has allowed researchers and integrated pest management (IPM) practitioners to develop and implement semiochemically-based pest control strategies. The major goal of this study was to evaluate, under field conditions, the response of male and female oriental fruit moth (OFM), codling moth (CM), redbanded leafroller (RBLR) and three lined leafroller (TLLR) to experimental kairomone lures in commercial apple orchards …
Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh
Evaluating Current And Future Potential Distribution Of Epiphytic Orchids In The Congo Basin With Ecological Niche Models, Michael L. Ngoh
Masters Theses
The Congo Basin Forest harbors a rich diversity of epiphytic communities, with the Orchidaceae alone making up more than 50% of all epiphytes in the region. Despite the huge diversity of epiphytes, many species, including epiphytic orchids, are at risk to a diverse array of threats. Climate change for instance poses severe threats to epiphytic orchids due to elevated temperatures, prolonged periods of droughts, as well as reduced rainfall across the Congo Basin Forest. In this study, we used ecological niche modeling and GIS techniques to identify spatial patterns of species richness, potential future climate refugia, and novel climatic suitability …
The Influence Of Cover Crop Termination Strategies And Supplemental Nitrogen On Sweet Corn Yield And Nitrogen Use Efficiency, Sachina Sunuwar
The Influence Of Cover Crop Termination Strategies And Supplemental Nitrogen On Sweet Corn Yield And Nitrogen Use Efficiency, Sachina Sunuwar
Masters Theses
Cover crops are instrumental in nutrient management and soil health. A field experiment was conducted from fall 2020 to summer 2021 to evaluate the efficiency of different cover crop termination techniques and supplemental nitrogen on sweet corn yield, ear quality and nitrogen use efficiency. The four termination types are herbicide and disk tillage (HDT), herbicide no-till (HNT), cultivation disk till (CDT), and roller crimped no-till (RCNT). These termination types were each divided into four different nitrogen treatment: 0%, 33%, 67% and 100% of the recommended doses (145 kg haˉ¹). Sweet corn yield was highest and % unfilled tip was lowest …
Diterpene Synthases Of The Rice Blast Fungus: Phylogenetic Analysis And Biochemical Characterization, Ayousha Shahi
Diterpene Synthases Of The Rice Blast Fungus: Phylogenetic Analysis And Biochemical Characterization, Ayousha Shahi
Masters Theses
Plant-pathogenic fungi harbor various specialized metabolites including diterpenoids that function as hormones and virulence factors. The fungus Magnaporthe oryzae is the causal agent of rice blast disease and can infect over 50 grass species. We demonstrate that the rice blast fungus encodes two diterpene synthases that produce normal pimara-8,15-diene and manoyl oxide scaffolds. Phylogenetic analysis of diterpene synthases among rice blast pathotypes showed functional conservation of the two core diterpene synthases amongst all pathotypes and suggests further expansion in select grass species. These insights into the blast fungal terpenome may inform efforts to counteract deleterious phytopathogens in crucial food crops.
Improving Water And Plant Growth Regulator (Pgr) Management Practices In Cotton: Cultivar Physiological Responses And Pgr Rates, Kurt Wedegaertner
Improving Water And Plant Growth Regulator (Pgr) Management Practices In Cotton: Cultivar Physiological Responses And Pgr Rates, Kurt Wedegaertner
Masters Theses
Cotton (Gossypium hirsutum L.) is grown in an increasingly unpredictable climate and often under rainfed conditions. Without irrigation to alleviate common drought conditions, cultivar selection becomes a primary tool in mitigating the negative effects of water-deficit stress. Cultivars can differ in water use under water-limited environments, which can affect crop performance. Moreover, cotton management must involve balancing vegetative and reproductive growth through the use of plant growth regulators (PGR) due to the plant’s perennial growth pattern. The efficacy of PGRs are dependent on many variables including environmental conditions, irrigation, and genetics (cultivar). In 2020 and 2021, a series of …
A Bioassay To Determine Poa Annua Responses To Indaziflam, Benjamin D. Pritchard
A Bioassay To Determine Poa Annua Responses To Indaziflam, Benjamin D. Pritchard
Masters Theses
Herbicide resistance within Poa annua is widespread in managed turfgrass systems. In 2020, a P. annua collection from a golf course in the southeastern United States was reported to be resistant to indaziflam as well as six other mode-of-action groups. Considering P. annua is the most troublesome weed in turfgrass, a bioassay to screen other collections with putative indaziflam resistance is needed. A dose-response experiment was conducted with ten concentrations of indaziflam (0, 250, 500, 750, 1000, 1250, 1500, 2000, 4500, and 9000 pM) in Gelrite® culture during 2021 and 2022. An herbicide-susceptible (S1) collection of P. annua, a …
Songbird-Mediated Insect Pest Control In Low Intensity New England Agriculture, Samuel J. Mayne
Songbird-Mediated Insect Pest Control In Low Intensity New England Agriculture, Samuel J. Mayne
Masters Theses
Global agricultural intensification has caused large-scale wildlife declines, but agricultural lands that maintain natural habitats can support healthy wildlife populations and receive significant ecosystem services from these natural communities. However, how on-farm biodiversity results in beneficial ecosystem services is highly variable and is reported to differ among taxa and guilds. One group that has attracted attention for their potential beneficial role in reducing pest abundance are birds. Understanding the role of bird communities and individual species in pest control could be important for managing farms under a low intensity agroecological framework. In New England, farmers are increasingly applying low intensity …
Screening For Binding Partners And Protein-Protein Interactions Of A Fungal Transcription Factor- Xdr1, Nishadi Punsara Gallala Gamage
Screening For Binding Partners And Protein-Protein Interactions Of A Fungal Transcription Factor- Xdr1, Nishadi Punsara Gallala Gamage
Masters Theses
Clarireedia spp. (formerly Sclerotinia homoeocarpaF.T. Bennett) is the causal agent dollar spot, the most economically important turfgrass disease impacting golf courses in North America. The most effective strategy for dollar spot control is repeated application of multiple classes of fungicides. However, reliance on chemical application has led to resistance to four classes of fungicides as well as multidrug resistance (MDR). Fungi are known to detoxify xenobiotics, like fungicides, through transcriptional regulation of three detoxification phases: modification, conjugation and secretion. Little is known, however, of the protein-protein interactions that facilitate these pathways. Following next-generation RNA sequencing of Clarireedia spp., a …
Relative Soybean Response To Aminocyclopyrachlor, 2,4-D, Dicamba, And Aminopyralid, Trey I. Clark
Relative Soybean Response To Aminocyclopyrachlor, 2,4-D, Dicamba, And Aminopyralid, Trey I. Clark
Masters Theses
This research compared the visual symptomology of four auxin herbicides applied at three rates to simulate tank contamination on non-auxin tolerant soybeans. The herbicides examined were aminocyclopyrachlor (ACP), 2,4-D, dicamba, and aminopyralid. The standard labeled rates (SLR) used to base the application rates were 0.12 kg ae ha-1 for ACP and aminopyralid while dicamba and 2,4-D used 1.12 kg ae ha-1. These four herbicides exhibit similar symptoms on soybeans which is problematic when diagnosing soybean response. One goal of this project was to obtain high-quality images of the four herbicide’s effect on soybeans, with the hope of …
Molecular Markers Within And Beyond Viburnum: A Single Set Of Ssrs For An Immense Genus, Trinity Paige Hamm
Molecular Markers Within And Beyond Viburnum: A Single Set Of Ssrs For An Immense Genus, Trinity Paige Hamm
Masters Theses
Comprised of more than 160 species, Viburnum is the largest genus in the Viburnaceae (formerly Adoxaceae) alongside Adoxa and Sambucus. The native range of Viburnum species spans much of the Northern Hemisphere and extends into the mountains of South America and Southeastern Asia. Their wide geographic range has made Viburnum particularly interesting to phylogeographers and phylogeneticists. This diverse genus is also horticulturally valuable with varying traits such as fragrance, fruit color, and bud and inflorescence form. There is sufficient morphological diversity in the genus for there to be more than 70 species and intraspecific hybrids in cultivation, and in …
The Role Of Low-Molecular Weight Fungal Metabolites In Eutypa Dieback Grapevine Trunk Disease, Dana Sebestyen
The Role Of Low-Molecular Weight Fungal Metabolites In Eutypa Dieback Grapevine Trunk Disease, Dana Sebestyen
Masters Theses
Eutypa dieback, one of several grapevine trunk diseases (GTDs), is of serious concern to the grape industry globally. This disease is caused by the fungus Eutypa lata but it is often seen in consortia growth with Phaeoacremonium minimum and Phaeomoniella chlamydospora. It is vital to understand the mechanisms for how this disease functions to develop control measures to combat it. Brown rot fungi are able to use a complex of low molecular weight (LMW) metabolites to induce a Fenton reaction to deconstruct woody tissue. These metabolites are part of a chelator mediated Fenton (CMF) chemistry that produces reactive oxygen …
Can Volunteers Learn To Prune Trees?, Ryan W. Fawcett
Can Volunteers Learn To Prune Trees?, Ryan W. Fawcett
Masters Theses
Volunteer pruning programs are becoming an important tool in helping municipal arborists manage the urban forest. To find if volunteers can learn to prune trees well, the ability of volunteers to prune small trees after receiving training was assessed in three different ways, a written exam, a pruning prescription assessment, and a pruning cut assessment. Volunteers were assigned to either an indoor, lecture-based training or an outdoor, hands-on training session. After the training volunteers were asked to complete a written exam to gauge their understanding of the curriculum. Volunteers were then asked to perform a pruning prescription on small street …
Supplementing East Tennessee Landscapes For Pollinators With Native Perennials, Amani Khalil
Supplementing East Tennessee Landscapes For Pollinators With Native Perennials, Amani Khalil
Masters Theses
Tennessee, home to the Great Smoky Mountains, is a biodiversity hotspot for many plant and animal species, yet it receives relatively few conservation dollars (Jenkins et al., 2015). As a biodiversity hotspot, this region may be home to many endemic species, but little is known about the abundance or diversity of insect pollinators. In order to both estimate pollinator communities in East Tennessee and pollinator forage preferences for native Tennessee plants, we established four plots, comprised of three plant families across five common land use types. Over two field seasons we collected nearly 7,300 insect specimens with a total sampling …
Effects Of Traditional And Microbially-Focused Restoration Techniques On Soil Communities In Tallgrass Prairies, Zachary J. Whitacre
Effects Of Traditional And Microbially-Focused Restoration Techniques On Soil Communities In Tallgrass Prairies, Zachary J. Whitacre
Masters Theses
Tallgrass prairies have virtually disappeared in many parts of their former range due to the conversion of this ecosystem to farmland. In more recent years there have been efforts to restore these prairies on reclaimed agricultural land. However, these restored prairies do not resemble their remnant counterparts in many ways, such as in soil microbial community composition and metrics related to carbon storage. In Chapter 1, I show that bacterial communities in a restored prairie and an adjacent remnant prairie in southwest Michigan differ in their immediate and longer-term responses to prescribed fire, a commonly used prairie restoration and maintenance …
Effects Of Am Fungi From Conventional And No-Till Michigan Crop Fields On Plant And Soil Health, Derek Bennett
Effects Of Am Fungi From Conventional And No-Till Michigan Crop Fields On Plant And Soil Health, Derek Bennett
Masters Theses
Centuries of conventional till (CT) management in agriculture has depleted soil organic matter (SOM) by over 50%. While only comprising 5% in most soils, SOM provides soil with fertility and productivity. To compensate for SOM depletion, producers have been forced to increase their reliance on fertilizer and irrigation to maintain yields. In the coming decades, climate change is expected to challenge food production and threaten an already fragile system. With no remaining land left to cultivate, conservation management strategies such as no-till (NT) look to restore SOM and increase the resilience of food production for an ever growing, increasingly food …
Modeling Emergence Of Annual Bluegrass (Poa Annua L.) In Hybrid Bermudagrass [C. Dactylon (L.) Pers. X C. Transvaalensis Burtt-Davy], Dallas Rose Taylor
Modeling Emergence Of Annual Bluegrass (Poa Annua L.) In Hybrid Bermudagrass [C. Dactylon (L.) Pers. X C. Transvaalensis Burtt-Davy], Dallas Rose Taylor
Masters Theses
Annual bluegrass (Poa annua L.; ABG) is a troublesome weed of turfgrass systems. A model to predict ABG emergence patterns could aid in timing measures to control ABG. Field research was initiated in January 2019 at the East Tennessee AgResearch & Education Center (ETREC) (Knoxville, TN) to better understand environmental conditions associated with ABG emergence. Plots (1 m2) included both hybrid bermudagrass [C. dactylon (L.) Pers. x C. transvaalensis Burtt-Davy, cv. ‘Tifway’, at a 1.5 cm cutting height] and bare soil. Emerged ABG inside a 1000 cm2 area in the center of each plot was …
Drought-Stress-Inducible Synthetic Promoters In Rice (Oryza Sativa), Paolo Montano Tagaloguin
Drought-Stress-Inducible Synthetic Promoters In Rice (Oryza Sativa), Paolo Montano Tagaloguin
Masters Theses
Drought can potentially affect the global rice supply. Recent climate modeling studies projected a more frequent and intense drought scenario, especially in top producing and exporting countries worldwide. Several drought-tolerant genes had been identified in recent years, and transgenic approaches had been employed to develop drought-tolerant rice. However, the constitutive expression of some drought-tolerant genes resulted in undesirable phenotypes and metabolic burden. The use of an inducible synthetic promoter is advantageous in preventing the possible pleiotropic effects from constitutively expressing a drought-tolerant gene. In this study, rationally designed synthetic promoters based on poplar (Populus trichocarpa) cis-motifs were …
Identifying Drought Tolerance Traits In Tennessee Soybean Genotypes: Recovery From Severe Water Deficit Stress, Samuel W. Purdom
Identifying Drought Tolerance Traits In Tennessee Soybean Genotypes: Recovery From Severe Water Deficit Stress, Samuel W. Purdom
Masters Theses
Ninety-four percent of U.S. grown soybeans are produced under rainfed conditions with intermittent droughts occurring late in the season during reproductive growth stages. Due to the temporary nature of drought, the ability of a crop to survive and recover effectively from water deficit stress is important for ensuring yield stability. In 2019 and 2020, two greenhouse experiments and two field studies were conducted to screen eleven soybean genotypes for transpiration response and recovery from water deficit stress and high vapor pressure deficit (VPD). In the first greenhouse study, soybean plants were grown in pots sealed to prevent evaporation and plants …
Determining Critical Fall Height For Bermudagrass Grown On Sand And Native Soil Root Zones, Taylor L. Williams
Determining Critical Fall Height For Bermudagrass Grown On Sand And Native Soil Root Zones, Taylor L. Williams
Masters Theses
Surface hardness is typically measured using a Clegg Impact Soil Tester (ASTM F355-D), but recent trends in sports turf are to use the F355-E missile as a potential alternative, because it may provide a more meaningful measurement. Forty traffic events were applied to ‘Tifway’ bermudagrass grown in an ASTM constructed sand root zone and a silt loam soil on the Center for Athletic Field Safety at the University of Tennessee. An F355-E was used to measure head injury criteria (HIC) for both root zones after every eight traffic events. Head injury criteria values were regressed to varying drop heights to …
Examining The Maternal Investment Of The Calyptra And Its Influence On The Sporophyte Offspring, Alessandra Marie Cabrera Aromin
Examining The Maternal Investment Of The Calyptra And Its Influence On The Sporophyte Offspring, Alessandra Marie Cabrera Aromin
Masters Theses
Maternal care is a critical component of offspring survival, development, and fitness in many organisms. In early diverging lineages of plants (mosses, liverworts, and hornworts), offspring sporophytes are physically attached to and nutritionally dependent on the maternal gametophyte throughout their lifespan. Mosses have a unique structure that is a maternal cap of gametophyte tissue that covers the sporophyte apex during critical developmental stages. The calyptra has shown to positively impact sporophyte survival and fitness. My research examines the influence of calyptra size on sporophyte growth and development.
Trait Variation And Long-Term Population Dynamics Of The Invasive Alliaria Petiolata (Garlic Mustard) Across Three Microhabitats In Its Invaded Range, Laura Hancock
Masters Theses
Long-term population dynamics across heterogeneous environments can be a major factor in determining species’ ability to expand their ranges and persist in novel environments. Whether and how the relative performance of populations in different microsites over time impacts invasion into new microsites is poorly understood. Though largely restricted to disturbed semi-shaded microhabitats in its home range, the invasive herb Alliaria petiolata (garlic mustard) successfully invades intact forest understories – a novel microhabitat – in its introduced range, where it is known to impact above and below ground community composition. To test the hypothesis that source-sink metapopulation dynamics may be promoting …