Digital Commons Network^™

Rare Occurrences Of Free-Living Bacteria Belonging To Sedimenticola From Subtidal Seagrass Beds Associated With The Lucinid Clam, Stewartia Floridana, Aaron M. Goemann

Masters Theses

Lucinid clams and their sulfur-oxidizing endosymbionts comprise two compartments of a three-stage, biogeochemical relationship among the clams, seagrasses, and microbial communities in marine sediments. A population of the lucinid clam, Stewartia floridana, was sampled from a subtidal seagrass bed at Bokeelia Island Seaport in Florida to test the hypotheses: (1) S. floridana, like other lucinids, are more abundant in seagrass beds than bare sediments; (2) S. floridana gill microbiomes are dominated by one bacterial operational taxonomic unit (OTU) at a sequence similarity threshold level of 97% (a common cutoff for species level taxonomy) from 16S rRNA genes; …

Potential Interaction Between Pre- And Post-Emergence Herbicides And The Efficacy Of Insecticide And Fungicide Seed Treatments In Cotton, Cory Joseph Vineyard

Masters Theses

An apparent reduction in the performance of neonicotinoid seed treatments in controlling thrips, especially in cotton, has been observed, which has coincided with the increased use of both pre- and post-emergence herbicides to control glyphosate-resistant weeds. The objective of this research was to evaluate the potential interactions of both pre- and post-emergence herbicides on the efficacy of insecticide and fungicide seed treatments in cotton

Aldicarb along with imidacloprid and thiamethoxam seed treatments reduced thrips numbers compared with non-treated seed. However, thiamethoxam did not provide effective control. Some pre-emergence herbicide treatments reduced plant health. While there was evidence that thrips injury …

Cowpea Adaptability To Southeastern Organic Farming Systems: Forage Productivity And Charcoal Rot Susceptibility, Samantha Lindsey Hill

Masters Theses

Cowpea (Vigna unguiculata (L.) Walp.) is a warm-season, multi-purpose legume that is well-adapted to the southeastern USA and has many traits that make it an attractive forage or cover crop for integration into organic production systems, including high rates of nitrogen (N) fixation, phosphorus (P) use efficiency, regrowth ability, and high digestibility. Eight cowpea varieties were evaluated under organic management at two locations in summer 2014 for stand establishment, forage yield and quality, and weed biomass.

Charcoal rot [Macrophomina phaseolina (Tassi) Goid.] is a fungal disease that is economically important to many host plant species. High temperatures and …

Physiological Evaluation And Root Morphological Differences Associated With Novel Drought Tolerant Corn (Zea Mays L.) Hybrids, Austin Gentry Scott

Masters Theses

Corn hybrids designated “drought tolerant” (DT) from three commercial seed companies were evaluated in order to determine the benefit of DT technology in a mid-south environment that may receive adequate but often poorly timed rainfall. Field research was conducted in 2014 and 2015 at Milan, TN where hybrid response to stress was evaluated at two planting dates and in non-irrigated and irrigated environments and greenhouse research was conducted in Jackson, TN to evaluate early season drought to plant physiology and root structure.

In 2014 and 2015, the non-irrigated trials received enough rainfall to create a high yielding environment. Since the …

Long-Term Impacts Of Conservation Management Practices On Soil Carbon Storage, Stability, And Utilization Under Cotton Production In West Tennessee, Candace Brooke Wilson

Masters Theses

Biogeochemical cycling of soil carbon (C) is heavily influenced by conservation agricultural (CA) practices. This study examined SOC stability under three CA practices: reduced nitrogen (N) fertilizer application rate, cover cropping, and zero-tillage implemented for 31 years. Respiration rates measured from a 602-day incubation period were fitted to a double-pool first order exponential model of SOC decomposition. The active [respired] SOC pool showed distinct differences between applications of reduced (34N kg ha^-1 [-1]) and high fertilization rates (101N kg ha^-1) combined with tillage, and suggest that high fertilizer applications with conventional tillage allocated more C into a …

Confirming Resistance To Prodiamine And Glyphosate In A Single Annual Bluegrass (Poa Annua L.) Biotype From Tennessee, Shane Matthew Breeden

Masters Theses

Annual bluegrass (Poa annua L.; POAAN) is a cool-season weed that commonly infests warm-season turfgrasses during winter dormancy. In spring 2012, poor POAAN control (<50%) was reported on golf course roughs in Alcoa, TN (35.75 °N, -83.88 °W) following treatment with a tank mixture of prodiamine (1120 g ha^-1[hectare]) and glyphosate (840 g ae ha^-1) during bermudagrass dormancy. The objective of this research was to determine if this POAAN biotype was resistant to prodiamine and glyphosate.

Using mature plants from the field, 81 of the 100 selections were not controlled by glyphosate and prodiamine; 96 of the 100 selections were not controlled by glyphosate, while 84 were unaffected by prodiamine. Only a single plant sampled was susceptible to both herbicides. …

Interactions Among Insect Defoliation, Insecticide Treatments, And Growth Rate In American And Hybrid Chestnuts, Ashley Elizabeth Case

Masters Theses

The American chestnut, Castanea dentata, was once one of the most useful and abundant canopy trees in eastern North American forests. Over the last 200 years, the species has been decimated by two exotic pathogens, Phytophthora cinnamomi and Cryphonectria parasitica, killing millions of trees and reducing surviving Castanea dentata to short-lived sprouts. Cryphonectria parasitica-resistance breeding programs are currently producing advanced backcross generations, which are being compared with pure American chestnut in field tests of growth performance and Cryphonectria parasitica resistance. The Asiatic oak weevil, Cyrtepistomus castaneus, has been identified as a common defoliator of chestnut seedlings in these …

Improving Management And Species Selection Of Warm-Season Forage Grasses For Southeast Production Systems, Christine Helen Gelley

Masters Theses

Beef producers need drought tolerant options when selecting forage grasses and also practical methods to estimate forage nutritive value, which this study aims to provide for warm-season grasses. The objective of the first experiment was to develop estimates of warm-season forage nutritive value and herbage mass based on harvest timing. The experiment was conducted from 2013 to 2015 at the University of Tennessee Plateau AgResearch and Education Center (PREC) in Crossville, TN. Four species were evaluated, each for two years: bermudagrass [Cynodon dactylon (L.) Pers. cv. Vaughn’s # 1], switchgrass [Panicum virgatum (L.) cv. Alamo], sorghum-sudangrass [Sorghum …

Population Structure Of Late Blight (Phytophthora Infestans) In Colombia And Ecuador And Downy Mildew (Peronospora Farinosa F. Sp. Spinaciae) On Spinach In Arizona And California, Rebecca Marie Lyon

Masters Theses

In this study, Phytophthora infestans and Peronospora farinosa f. sp. spinaciae populations were analyzed using single nucleotide polymorphisms (SNPs). In Ecuador and Colombia, Phytophthora infestans causes significant damage to potato and tomato and the epidemiology is known to be highly clonal. Our objective was to measure population structure within the context of this clonal epidemiology using both synonymous and nonsynonymous markers. Candidate SNP sites were selected by comparing the draft genomes of the Ecuadorian isolates EC1-3527 and EC1-3626. Genotypes were assessed directly from infected tissue using a targeted sequencing approach. A total of 54 polymorphic sites were assessed in 93 …

Comparison Of Seed Yield, Oil And Phenotypic Traits Among Selected Parents And Crosses Of Niger, Victoria Grace Benelli

Masters Theses

Niger (Guizotia abyssinica (L.f) Cass.) is primarily marketed as favorite seed among American goldfinches (Carduelis tristis) as well as pine siskin, redpoll, house finches, and ground feeding birds like quail and dove. As a part of a balanced diet, it is crucial for these species to consume a higher percentage of fats than other bird species. Fourteen niger accessions of Indian, Ethiopian, and American origin were obtained from USDA/ ARS germplasm collection at Pullman, WA and planted in August 2012 at the East Tennessee Research & Education Center. Five of these accessions were crossed to form different …

Economic And Environmental Optimization In The Supply Of Switchgrass In Tennessee, Jia Zhong

Masters Theses

The low efficiency of collection, storage and transportation in the switchgrass supply chain has hindered the commercialization of a switchgrass-based biofuel industry, even given its ecological and environmental advantages in carbon sequestrate, soil quality, water use, and pollution pressure. Thus, designing a switchgrass-based supply chain balancing both environmental and economic performance is important to expedite the development of the cellulosic biofuel industry to meet the national energy plan.

The objectives of this study are to 1) determine economic cost and multiple environmental outcomes in feedstock supply chains and 2) identify the relation between the economic and environmental performances. The first …

Rnai Mediated Silencing Of Cell Wall Invertase Inhibitors To Increase Sucrose Allocation To Sink Tissues In Transgenic Camelina Sativa Engineered With A Carbon Concentrating Mechanism, Joshua Zuber

Masters Theses

Plant invertases are a class of proteins that have enzymatic function in cleaving sucrose to fructose and glucose. Cell wall invertase, located on the exterior of the cell wall of plant cells, plays a key role in the unloading of sucrose from the apoplast to the sink tissues. Cell wall invertase interacts with an inhibitor, cell wall invertase inhibitor, post-transcriptionally to regulate its activity. The inhibitor is constitutively expressed in pollen development, early developing seeds, and senescing leaves: indicative of sucrose allocation being a limiting factor at these stages of development. We introduced algal bicarbonate transporters LCIA/CCP1 to Camelina sativa …

A Gravity Investigation Of The Tobacco Root Batholith Southwest Montana, Stephen Charles Tatum

Masters Theses

The objective of this research was to delineate and profile the Late Cretaceous Tobacco Root batholith in southwestern Montana through the application of the gravitational method. This survey was accomplished by obtaining 232 gravity measurements in four profiles across the batholith. After correcting for known variations in the gravity field, a Bouguer anomaly map of the batholith and surrounding host rocks was created. Four residual gravity profiles and map, created by subtracting the regional gravity from the Bouguer anomaly, reveal a maximum negative gravity anomaly in the center portion of the batholith which is parallel to the trend of the …

Distribution Of Abc Transporter Genes Across The Plant Kingdom, Thomas Scott Lane

Masters Theses

The ATP-binding cassette (ABC) transporter gene superfamily is ubiquitous among extant organisms. ABC transporters act to transport compounds across cellular membranes and are involved in a diverse range of biological processes and functions including cancer resistance in humans, drug resistance among vertebrates, and herbicide resistance in weeds. This superfamily of genes appears to be larger and more diverse in the plant kingdom—yet, we know relatively less about ABC transporter function in plants compared with mammals and bacteria. Therefore, we undertook a plant kingdom-wide transcriptomic survey of ABC transporters to better understand their diversity.

We utilized sequence similarity-based informatics techniques to …

Diallel Analysis Of Biomass And Ethanol Yield In Leaves Versus Stems Of Lowland Switchgrass, Alexandria Christina Desantis

Masters Theses

Switchgrass (Panicum virgatum L.) is a warm season perennial grass used widely as a forage crop. This research seeks to address improving biomass yield and predicted ethanol yield through certain traits by the following objectives: (1) differences in average biomass and predicted ethanol yields from leaves versus stems, (2) genetic variance and heritability estimates of biomass and ethanol yield traits (3) general (GCA) and specific combining ability (SCA) among the five parents for biomass and ethanol yield, and (4) correlations between agronomic and morphological traits. Five parents with varying morphological traits were crossed in a diallel design, excluding selfs. …

Development And Evaluation Of A Cost Effective Plant Growth Media Moisture Sensor And Development Of An Aqueous Data Transmission System For Irrigation Purposes, Steven Michael Pickett

Masters Theses

The ability to accurately monitor and transit the moisture content of soilless growing media in the rooting zone is critical for plant-based research, production of high value crops, and other agricultural production. The focus of this study is the development and evaluation of a cost effective moisture sensor designed to measure the plant-available moisture content of growing media and the development of a aqueous data transmission method for relaying this information back to a central location. While there are currently many commercially available soil moisture sensors on the market, the aim of this research is not to develop a more …

Thermocycle-Regulated Wall Regulator Interacting Bhlh Encodes A Protein That Interacts With Secondary-Cell-Wall-Associated Transcription Factors, Ian P. Whitney

Masters Theses

Lignocellulosic biomass is one of the most abundant raw materials on earth that can be utilized to created carbon-neutral biofuels as a replacement for conventional fossil fuels. In order to create ideal energy crops, the regulation and deposition of cell wall polysaccharides must first be fully understood. Improved understanding of cell wall regulation will enable selection of traits that can optimize biofuel feedstocks. Herein, I utilize the grass model system Brachypodium distachyon in order to understand the transcriptional regulation of secondary cell wall deposition. Gene expression profiling was used to elucidate transcription factors that regulate secondary cell wall biosynthesis. Through …

Efficient Irrigation For Recreational Turfgrass In New England: Evapotranspiration And Crop Coefficients, James W. Poro

Masters Theses

As water demand increases it will become more imperative for golf course superintendents, landscape managers, and other industry professionals to improve water use efficiency in the management of recreational turfgrass. Scheduling irrigation according to actual turfgrass evapotranspiration rates (ET_T) is an integral component of efficient irrigation practices. Impracticality of field derived ET_T for industry use, however, directs the need of weather station derived reference (predicted) evapotranspiration (ET₀). To accurately predict (estimate) ET_T of turf and other crops, scientifically derived landscape (crop) coefficients (K_c values) are used in conjunction with mathematical models that incorporate …

Allelopathic Effects Of S. Canadensis On The Germination Of Native Prairie Plants, James David Megenhardt

Masters Theses

Solidago canadensis has become a aggressive species of North American prairie forb throughout the world and within restored prairies throughout North America, causing the loss of biodiversity within those ecosystems. While reproductive methods of wind dispersed seeds and clonal expansion through rhizomes has helped S. canadensis colonize and spread through these ecosystems, S. canadensis also releases allelopathic chemicals which may inhibit the germination and growth of competing species. What was unknown is if these same allelopathic chemicals which give S. canadensis an edge within foreign ecosystems might also explain why S. canadensis is so prolific in restored North American …

The Functional Role Of Leaf Nutrients In An Old-Field Successional Community, Kirstin I. Duffin

Masters Theses

In functional ecology, traits that capture aspects of plant performance are used to understand how organisms interact with their environment. Leaf nutrients are an example of a functional trait that directly links to plant metabolic processes and therefore may describe plant assemblage dynamics. Multivariate leaf nutrient analyses may be used with other functional traits to understand ecological strategies because they are a direct measure of leaf metabolic processes and can describe nuances in plant allocation patterns. In this thesis, I explored (1) whether a suite of leaf nutrients (carbon, nitrogen, phosphorus, potassium, calcium, and magnesium) was related to plant growth …