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Articles 1 - 15 of 15
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Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant
Characterization Of Lignin Structural Variability And The Associated Application In Genome Wide Association Studies, Nathan D. Bryant
Doctoral Dissertations
Poplar (Populus sp.) is a promising biofuel feedstock due to advantageous features such as fast growth, the ability to grow on marginal land, and relatively low lignin content. However, there is tremendous variability associated with the composition of biomass. Understanding this variability, especially in lignin, is crucial to developing and implementing financially viable, integrated biorefineries. Although lignin is typically described as being comprised of three primary monolignols (syringyl, guaiacyl, p-hydroxyphenyl), it is a highly irregular biopolymer that can incorporate non-canonical monolignols. It is also connected by a variety of interunit linkages, adding to its complexity. Secondary cell wall …
Corn (Zea Mays L.) Production In Living Mulch Systems, Grazing Potential, And Economic Viability, Marcia Peireira Quinby
Corn (Zea Mays L.) Production In Living Mulch Systems, Grazing Potential, And Economic Viability, Marcia Peireira Quinby
Doctoral Dissertations
Living mulch (LM) is a practice in which forages are grown simultaneously with the main crop, serving as a living cover throughout the growing season. The LM systems were developed to alleviate concerns of soil depletion and finding ways to reduce tillage negative effects on soil productivity. In addition, when legumes are use can decrease the reliance on N fertilizer. The use of corn in LM have been previously studied due to the crop being a large commodity in the U.S.; In addition, the ability to graze the LM after corn production can increase the land use efficiency. To determine …
Native Soil Virus Abundance, Composition, And Mobility Under Natural And Managed Agricultural Conditions, Regan Mcdearis
Native Soil Virus Abundance, Composition, And Mobility Under Natural And Managed Agricultural Conditions, Regan Mcdearis
Doctoral Dissertations
Soil viruses are ubiquitous in the environment and important for their influence on host community composition and function. Viral infection influences host evolution, metabolism, function, diversity, community evenness, and more. As host bacteria play critical roles in agricultural systems, including nutrient cycling and soil aggregate formation, the influence which soil viruses have on their hosts makes them key players in these systems. However, many important questions remain regarding virus abundance and distribution under human imposed and natural conditions in agricultural systems. Understanding how these conditions impact virus abundance, transport, and community structure is critical for a broader understanding of soil …
The Characterization Of Traits Associated With Freezing Tolerance In Perennial Ryegrass, Rachael Preston Bernstein
The Characterization Of Traits Associated With Freezing Tolerance In Perennial Ryegrass, Rachael Preston Bernstein
Doctoral Dissertations
Plants are constantly subjected to adverse environmental conditions that alter their growth and productivity, with an estimation that approximately 50% of annual average crop yields are reduced due to abiotic stresses. Freezing stress causes desiccation and ice damage in plants and is becoming more important as temperatures and unpredictable weather patterns increase. Normally, plants acclimate to cold temperatures as winter approaches and deacclimate as temperatures warm in the spring. Cold acclimation in fall is required for plants to build up their cellular defenses against desiccation and intracellular ice formation, while deacclimation is the process in which plants metabolize protective compounds …
Soil Health Assessment For The Agroecosystems Of West Tennessee, Surendra Singh
Soil Health Assessment For The Agroecosystems Of West Tennessee, Surendra Singh
Doctoral Dissertations
Soil health assessment is important for making informed sustainable management decisions in production systems. An established standardized method to quantify soil health is lacking and the validity of the existing methods across agroecoregions and cropping systems is not yet proven. Therefore, this study aims to evaluate the feasibility of widely discussed three soil health tests - Haney’s Soil Health Test (HSHT), Comprehensive Assessment of Soil Health (CASH), and Alabama Soil Health Index (ASHI) to assess soil health in diverse cropping systems of Tennessee. Since these approaches were originally developed for specific agroecoregions, we hypothesized that these tests are not sensitive …
Soil Moisture Sensitivity Of Microbial Processing Of Soil Organic Carbon, Shikha Singh
Soil Moisture Sensitivity Of Microbial Processing Of Soil Organic Carbon, Shikha Singh
Doctoral Dissertations
Soil organic carbon (SOC) is the largest terrestrial C pool and understanding SOC decomposition in response to environmental factors is critical for accurate predictions of climatic change. Soil moisture is one of the most important, yet less explored, environmental factors controlling soil microbial respiration. The relationship between soil moisture and respiration also varies with soil texture. Currently, it is difficult to predict feedbacks to climatic changes from changes in soil moisture, as most earth system models lack site-specific, experimentally-derived parameters to represent soil moisture-texture-respiration relationships. The overarching goals of this dissertation are to gain a fundamental understanding of the interactive …
The Good, The Bad, And The Ugly: Pollinators As Vectors Of Mummy Berry Disease In Highbush Blueberry, Matthew Boyer
The Good, The Bad, And The Ugly: Pollinators As Vectors Of Mummy Berry Disease In Highbush Blueberry, Matthew Boyer
Doctoral Dissertations
Background: Many plants must balance the need for pollination services with mediating the risk of pollinator-vectored pathogens. Vaccinium corymbosum, highbush blueberry, is negatively affected by an insect-vectored, fungal plant pathogen, Monilinia vaccinii-corymosi (MVC), the cause of mummy berry disease, in which the asexual spore mimics pollen grains and is transferred from blighted tissue to flowers via pollinators, resulting in inedible, hardened fruits. Highbush blueberry plants require outcrossed pollen for maximum yield and fecundity. Therefore, yield of blueberry plants rely on a balance between adequate pollination service and disease avoidance. Approach: To explore the relationship between pollinator community and infection …
Investigation Of Fungicide Resistance Mechanisms And Dynamics Of The Multiple Fungicide Resistant Population In Sclerotinia Homoeocarpa, Hyunkyu Sang
Doctoral Dissertations
A filamentous ascomycete fungus Sclerotinia homoeocarpa causes dollar spot, which is the most important disease of turfgrasses in the United States. Despite the increased number of reports of site-specific fungicide resistance and a recent report of multidrug resistance (MDR) in S. homoeocarpa field populations, the genetic mechanisms behind resistance or reduced sensitivity to fungicides remain poorly explained in the fungus. In order to prevent further development of fungicide resistance in the dollar spot pathosystem, a detailed elucidation of mechanisms of site-specific fungicide resistance and MDR is needed. In addition, the previous studies of MDR in fungi mostly focused on efflux …
Evaluating The Role Of Glutathione In Detoxification Of Metal-Based Nanoparticles In Plants, Chuanxin Ma
Evaluating The Role Of Glutathione In Detoxification Of Metal-Based Nanoparticles In Plants, Chuanxin Ma
Doctoral Dissertations
The potential risks from metal-based nanoparticles (NPs) in the environment have increased with the rapidly rising demand for and use of nano-enabled consumer products. Plant’s central roles in ecosystem function and food chain integrity ensure intimate contact with water and soil systems, both of which are considered sinks for NPs accumulation. Thus, this dissertation describes three main objectives to comprehensively understand the interactions between plants and NPs and to characterize the role of glutathione (GSH) in detoxification of metal-based NPs in plants at physiological, biochemical, and molecular levels. (1) The effects of cerium oxide (CeO2) and indium oxide …
Novel Advancements For Improving Sprout Safety, Kyle S. Landry
Novel Advancements For Improving Sprout Safety, Kyle S. Landry
Doctoral Dissertations
All varieties of bean sprouts (mung bean, alfalfa, broccoli, and radish) are classified as a “super-food” and are common staples for health conscious consumers. Along with the proposed health benefits, there is also an inherent risk of foodborne illness. When sprouts are cooked, there is little risk of illness. The purpose of this dissertation was to explore novel techniques to minimize or prevent the incidence of foodborne illness associated with the consumption of sprouts. Three areas were investigated: 1) the use of a biocontrol organism, 2) the use of a novel spontaneous carvacrol nanoemulsion, and 3) the influence of the …
Assessing Kiln-Produced Hardwood Biochar For Improving Soil Health In A Temperate Climate Agricultural Soil, Emily J. Cole
Assessing Kiln-Produced Hardwood Biochar For Improving Soil Health In A Temperate Climate Agricultural Soil, Emily J. Cole
Doctoral Dissertations
Soil quality has become a major factor used in assessing sustainable land management and the overall environmental quality, food security, and economic viability of agricultural lands. Recently, biochar has been touted as having many potential uses as a soil amendment for improving soil quality, specifically improving cation exchange capacity, pH and nutrient availability. However, soil biology also plays a significant role in biogeochemical processes that influence soil health and should be included in a more comprehensive study of soil health. This dissertation describes 4 projects within the same 3-year field study with the cumulative purpose of better understanding the effect …
Effects Of Overexpression Of Sap12 And Sap13 In Providing Tolerance To Multiple Abiotic Stresses In Plants, Parul R. Tomar
Effects Of Overexpression Of Sap12 And Sap13 In Providing Tolerance To Multiple Abiotic Stresses In Plants, Parul R. Tomar
Doctoral Dissertations
Environmental stresses are the one of the main reasons for the decline of crop production worldwide. In the past years, a major focus has been on improving plant species and their tolerance towards these stresses but not much has been achieved because of the limited knowledge of the gene/network of genes that might be involved in providing tolerance to such multiple abiotic stresses. Recently, members of Stress Associated Protein (SAP) family in plants have been shown to impart tolerance to multiple abiotic stresses. There are 14 SAP genes in Arabidopsis thaliana and these proteins contain A20, AN1 and C2H2 zinc …
Enhancing The Sustainability Of Integrated Biofuel Feedstock Production Systems, Amanda Joy Ashworth
Enhancing The Sustainability Of Integrated Biofuel Feedstock Production Systems, Amanda Joy Ashworth
Doctoral Dissertations
As use of second-generation biofuel crops increases, so do questions about sustainability, particularly their potential to affect fossil energy consumption and greenhouse gas emissions. Nitrogen (N)-fixing legumes interseeded into switchgrass (Panicum virgatum L.) may be an alternative to inorganic fertilizer in forage-feedstock systems. Research herein is divided into four general experiments: I). N replacement and feedstock impacts from legume intercrops and biochar in switchgrass; II). N-fixation rates in intercrop systems; III). impacts of biofuel systems under enhanced climate change; and, IV). projected sustainability of regional switchgrass production. Approaches included: characterization of feedstock/forage quality traits based on legume, biochar and …
Identification And Epidemiological Features Of Important Fungal Species Causing Sooty Blotch On Apples In The Northeastern United States, Angela Marie Madeiras
Identification And Epidemiological Features Of Important Fungal Species Causing Sooty Blotch On Apples In The Northeastern United States, Angela Marie Madeiras
Doctoral Dissertations
The sooty blotch and flyspeck (SBFS) complex causes blemishes on apples in humid, temperate growing regions worldwide. In contrast to flyspeck etiology, the many species of fungi causing sooty blotch (SB) have not been well studied. The first set of objectives in this study was to use PCR to identify SB species isolated from apples and selected reservoir hosts in the northeastern United States, and to identify patterns of species distribution on hosts and among sites. Results indicated that Geastrumia polystigmatis was the predominant species on apples, whereas Peltaster species were more common on reservoir hosts. Species distribution varied among …
Effects Of Leaflet Orientation And Root Morphology On Physiological Traits And Yield In Soybeans., Richard Dewayne Johnson
Effects Of Leaflet Orientation And Root Morphology On Physiological Traits And Yield In Soybeans., Richard Dewayne Johnson
Doctoral Dissertations
Drought is the most important abiotic stress adversely affecting soybean (Glycine max (L.) Merr.) yield. Leaflet orientation has been shown to reduce leaflet temperatures and transpiration while root morphology has been related to slower wilting phenotypes. The objective of this study was to investigate effects of leaflet orientation and rooting morphology on whole plant transpiration, yield, water use efficiency, and other physiological traits in soybeans using grafting techniques, population lines, near-isogenic lines, and restrained leaf canopy experiments. Experiments were conducted in Knoxville, TN with additional yield trial plots at Springfield, Spring Hill, and Milan, TN. Data were collected on …