Digital Commons Network^™

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 …

4-H Wildlife Habitat Education Program: A Qualitative Study On Career Exploration, Ronnie Lee Cowan

Masters Theses

There are documented studies on the Wildlife Habitat Education Program (WHEP) that relate to building life skills of participants. However, no literature was found that measured the perceptions of the participants towards a career in wildlife after participating in WHEP. To add validity to the program a focus group was conducted at the Tennessee 4-H wildlife judging contest to describe the WHEP participants’ perceptions of careers in wildlife after the completion of the annual program. Focus group participants indicated that participating in WHEP peaked their interest in wildlife and provided an opportunity to experience the importance of natural resource management.

Analysis Of Beef Cattle Producers’ Propensity To Adopt Pasture Management And Prescribed Grazing East Of The 100th Meridian, Kristen Elizabeth Oliver

Masters Theses

Pasture management and grazing practices affect animal productivity, soil carbon storage and soil and water quality. Poor pasture and grazing management practices can cause soil erosion, nitrogen leaching, and runoff into streams and waterways. Based on a survey of cattle farmers east of the 100^th meridian, the following two papers estimate how farm operator, farming operation, and attitudinal variables influence the propensity to use pasture management and prescribed grazing, as well as use of specific pasture management and prescribed grazing practices.

Key findings from the first paper are that individual pasture management and prescribed grazing practices are strong indicators …

Salmonella In Low Water Activity Foods: Physiological, Genetic Modification And Control Methods, Wei Chen

Doctoral Dissertations

The objective of this study was to evaluate the expression of fatty acid associated genes (fabA, fabD and cfa) of five serovars of Salmonella exposed to sugar over a 14-day period. Changes in the fatty acid composition of Salmonella Tennessee in glycerol solutions of different water activity (a_w) (1.0-0.6) and the relationship between survival and fatty acid modification (as altered by exogenously supplied fatty acids) at a_w 1.0-0.6 were also determined. Furthermore, the antimicrobial activities of carvacrol, cinnamaldehyde, and lauric arginate (LAE) alone or in combination against Salmonella Tennessee in a laboratory model of …

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 …

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 …

Characterization Of The Role Of Alpha-Arylphorin In The Heliothis Virescens Midgut Response To Cry1ac Toxin From Bacillus Thuringiensis, Jerreme Jamael Jackson

Doctoral Dissertations

Homeostasis of the intestinal epithelium in Heliothis virescens is mediated by the proliferation and differentiation of multipotent intestinal stem cells (ISCs) that lie adjacent to the basal lamina. In response to extrinsic and intrinsic signals, ISC proliferation and differentiation promotes epithelial growth and regeneration following the loss of integrity. We tested the in vivo effects of the ISC mitogen, a [alpha]-arylphorin, on ISC proliferation and the morphological changes of the midgut during larval development. Additionally, we examined how these changes affected the intestinal epithelium response to Cry1Ac toxin from Bacillus thuringiensis. Histological and in vitro evidence supported two distinct …

Identification And Confirmation Of Quantitative Trait Loci For Protein Concentration And Improved Amino Acid Composition In Glycine Max, Jeneen Samantha Abrams

Doctoral Dissertations

The demand for poultry and swine production has grown continually as the world population increases. There will be an estimated 8 billion people to feed in the world by 2025. Soybean meal is the most important plant protein ingredient for poultry and swine feedstock. Globally, the US produces 32% of the world’s soybean. Although soymeal is nearly a complete plant protein, it is highly supplemented with sulfur-containing amino acids such as cysteine and methionine. The objectives of this project were to utilize molecular markers known as single nucleotide polymorphisms (SNPs) to identify genomic regions associated with protein concentration and amino …

Factors Impacting Ffa Involvement After High School, Danielle Eve-Marie Sanok

Masters Theses

The purpose of this study was to determine the factors that influence FFA members to continue or discontinue with their FFA experience past high school. The specific objectives of this study were to determine the reasons why students discontinue with their FFA experience past high school, determine membership needs from the Collegiate and Alumni FFA Organization and ways to overcome membership attainment barriers.

Data collection methods included three sets of focus groups: (a) one for inactive FFA members, (b) one for current Collegiate FFA members, and (c) one for current and past State Officers. Data was analyzed using the thematic …

Impact Of International Student Teachers On A New South Wales, Australia Community Over Ten Years: A Qualitative Study, Derek Anthony Brawner

Masters Theses

The purpose of this study was to evaluate change in the impact of American agriculture education student teachers on a rural community in New South Wales, Australia over ten years. The study analyzed interviews with ten participants of the American Student Teaching Program in a New South Wales community. The researcher was a student teacher in the New South Wales community for ten weeks and taught agriculture in one of the community’s high schools. Exposure to individuals in the community and also recommendations from the agriculture teachers and principals of the Australian school, which included the principal, deputy principal, one …

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 …