Life Sciences Commons^™

Effects Of Environment And Genotype On Charcoal Rot Development On Soybeans, Micah Diane Doubledee

Graduate Theses and Dissertations

Charcoal rot of soybean, caused by the soilborne fungus Macrophomina phaseolina (Tassi) Goid, is a disease associated with high soil temperature and low soil moisture. Above-ground symptoms, which can be difficult to distinguish from drought symptoms, include low vigor, dead leaves that remain attached to the plant, early senescence and yield loss. Irrigation limits damage, but does not prevent colonization of the tissue by the pathogen. No soybean line is immune to M. phaseolina, but a few lines may have moderate resistance. The objectives of this research were to 1) determine the effects of genotype and drought on the development …

Soybean Maturity Group Tradeoffs: Irrigation, Weed Control, And Nitrogen Fixation, Ryan Wegerer

Graduate Theses and Dissertations

This thesis is divided into four chapters. Chapter I introduces the rationale behind the study and gives a brief overview of the overall study covering weed control, irrigation needs and nitrogen fixation amounts across soybean maturity group. Chapter II will go into further detail outlining the first applied experiment dealing with weed control and irrigation issues. Alternative weed control methods are analyzed in conjunction with irrigation risk analysis across soybean maturity group in response to agricultural issues of glyphosate resistance and declining ground water supply in the Arkansas delta region. Chapter III will jointly examine irrigation application amounts and nitrogen …

Investing In An Agricultural Legacy, Leo Paul Goeringer

Graduate Theses and Dissertations

America's agricultural producers continue to age. According to the U.S. Census of Agriculture, the average age of farm operators increased from 55.3 in 2002 to 57.1 in 2007. During the same period, the Census shows a thirty percent decrease in the number of farmers under age 25. Young and beginning producers (YBPs) entering agriculture face high startup costs and a shortage of land to own or rent.

With these concerns in mind, this manuscript details the impact of an innovative proposed loan program for YBPs in Arkansas, which would offer concessionary interest rates and loan fees by participating banks for …

Food Environment And Childhood Obesity, Yucong Jiao

Graduate Theses and Dissertations

This thesis examines whether children's food environment, especially food stores that have fresh produce, affects obesity prevalence among elementary school children in the state of Arkansas. Misclassified food outlet types in the Dun and Bradstreet commercial data set were first corrected and then food environment measures were computed and aggregated to geographic regions corresponding to school attendance areas. After applying classical panel estimation, it was found that the fixed effects model fit the data best. Results indicate that an additional supermarket within a one-mile radial of the census neighborhood block center will bring down childhood obesity prevalence by 0.58 percent, …

Economic Implications Of Extreme Heat Effects On Rice Yield And Milling Quality In Arkansas, Nate Lyman

Graduate Theses and Dissertations

Future increases in global surface temperature threaten those worldwide who depend on rice production for their livelihoods and food security. Past analyses of extreme heat effects on rice production have focused on paddy yield and have not accounted for the detrimental impact of extreme heat on milling quality outcomes which ultimately determine edible (marketable) rice yield and value. Using rice yield and milling quality data on six popular rice cultivars from Arkansas, USA, combined with on-site, half-hourly and daily temperature observations, this study finds a nonlinear effect of extreme heat exposure on yield and milling quality. A 1 °C increase …

Investigations Of Protein-Lipid Interactions In Model Membranes: Influence Of Aromatic Anchoring Residues And Buried Polar Residues, Nick Gleason

Graduate Theses and Dissertations

To investigate in detail the interactions between transmembrane proteins and the lipid bilayers in which they are constituted, designed model peptides with selective isotopic labels were synthesized and analyzed by means of solid-state deuterium NMR spectroscopy. Starting from the well-characterized model peptide GWALP23, acetyl-GGALW(LA)6LWLAGA-amide, several Trp to Tyr mutations were compared to evaluate their respective interfacial anchoring abilities. It was found that Tyr, substituted on either or both termini, can effectively anchor the transmembrane alpha-helix, which then adopts a similar transmembrane topology in a range of bilayer thicknesses. Nevertheless, a consistent ~10° shift in tilt direction (helix rotation) is observed …

Peptoid Based Slide Coatings For Disease Detection Via Elisa Microarray Analysis, Melissa Lea Hebert

Graduate Theses and Dissertations

Poly-N-substituted glycines (peptoids) are a very versatile family of synthetic molecules that can be customized for any number of applications. In this study, we chose to use peptoids as a foundation for sandwich ELISA microarray analysis with a long term goal of creating an early detection device for complex diseases such as cancer. The peptoids were designed to self-assemble into microspheres to be used in coatings on the surface of the microarray substrates to increase the surface area available for antibody attachment. This increased antibody density would lead to an increase in the microarray analysis sensitivity and dynamic range. Studies …

Maternal Environment And Fescue Cultivar Effects On Growth, Development, And Fertility Of Beef Heifers, Jennifer Denyse Patterson

Graduate Theses and Dissertations

Eighty Brahman-influenced cows (5.6 BCS) were assigned to graze common bermudagrass (CB) or toxic tall fescue (E+) during a 60-d breeding season. Body condition (BC) was assessed at d 0, 30, and 60 of breeding season. Cows were managed to achieve marginal (4.2 BCS) or good (6.3 BCS) BC during last trimester. Heifer birth and weaning (WW; 7 to 8 mo) weights were recorded. The Angus sired heifers were weighed and randomly assigned to E+ or non-toxic (Novel) tall fescue at 9 to 10 mo of age for 190d. Heifer weight, growth data, and antral follicle count (AFC) were collected …

Effects Of Head Position And Head-Supported Mass On Nerve Function Of The Flexor Carpi Radialis Muscle In Healthy Individuals, Bethany Lauren Shivers

Graduate Theses and Dissertations

Long-term exposure to head-supported mass (HSM) has been linked with spinal degeneration including foraminal stenosis and disc deterioration. Anecdotally, HSM has also been linked to neck and arm pain and muscle atrophy, but nerve function has not been tested specifically. The combined effect of various head positions and HSM may be sufficient to compress the nerve root in aviators and Soldiers during job performance, potentially leading to short- and long-term neuromuscular effects. The Hoffmann (H) reflex, a well-established measure of nerve function, has shown to be sensitive to changes in nerve root space which occurs with different head positions. This …

Evaluation Of Isothiocyanates And Herbicide Programs As Methyl Bromide Alternatives For Weed Control In Polyethylene-Mulched Tomato And Bell Pepper, Pratap Devkota

Graduate Theses and Dissertations

Methyl bromide (MeBr), a Class I ozone –depleting substance, has been banned for ordinary agricultural uses. In the absence of an effective MeBr alternative, weed control is a major challenge for commercial tomato and bell pepper production. Field trials were conducted at Fayetteville, AR, to compare allyl isothiocyanate (ITC), metam sodium, and herbicide programs with the standard MeBr application (mixture of MeBr plus chloropicrin at 67% plus 33%, respectively, hereafter referred to as MeBr) for crop injury, weed control, viable yellow nutsedge tubers, and marketable yield in low–density polyethylene (LDPE) mulched tomato and bell pepper production. In addition, herbicide programs …

Characteristics Of Quality Agricultural Magazine Capstone Courses Based On The Five R'S Model, Traci Nicole Rushing

Graduate Theses and Dissertations

This study sought to assess students' and instructors' perceptions regarding the value of an agricultural communications magazine capstone course at three universities that were identified as exemplary in an effort to describe the characteristics leading to the course's success. Using a qualitative survey methodology, the investigator administered an open-response survey, conducted personal interviews with purposively-selected students in each course and the instructors, and made field observations. Both the interviews and the surveys consisted of six, in-depth questions crafted after Andreasen's (2004) of a successful magazine capstone course. Based on students' and instructors' perceptions through the lens of Andreasen's (2004) model, …

Evaluation Of Internal Markers For Predicting Digestibility And Fecal Output By Cattle Fed Bermudagrass Hays Of Varying Quality, Juvenal Kanani

Graduate Theses and Dissertations

The potential of in situ rumen undegradable dry matter (RUDM), indigestible neutral-detergent fiber (INDF), indigestible acid-detergent fiber (IADF), acid-detergent insoluble ash (ADIA), alkaline-peroxide lignin (APL), and acid-detergent lignin (ADL) to predict digestibility (DMD) and fecal output (FO) by cattle fed bermudagrass [Cynodon dactylon (L.) Pers.] hay-diets categorized by their low (L), medium low (ML), medium high (MH), or high (H) CP concentrations (79, 111, 131, and 164 g/kg DM, respectively) was evaluated. The second objective was to evaluate the effects of time (0600, 1200, 1800, and 2400 h) of fecal sampling on the prediction of FO and DMD. A replicated …

Determination Of Methionine And Lysine Requirements Of Growing Broilers Using The Ideal Protein Concept, Changji Lu

Graduate Theses and Dissertations

Three experiments were conducted to evaluate the responses of broiler performance to Lysine (Lys) and Methionine (Met) during the starter, grower, and finisher feeding phases. All the experimental diets were formulated based on the Ideal Protein Concept.

Experiment 1 evaluated the responses to Lys and Met on live performance of young broiler chickens from 0 to 18 d of age. The mean amino acid ratios to Lys suggested by literature values were used in the formulation based on the Ideal Protein Concept. Six levels of Lys and eight levels of supplemental Met were used in the diets resulting in a …

The Impact Of Selected Forage Legumes On Cattle Performance, Forage Production, And Soil Quality, And Evaluation Of Legume Persistence Under Grazing, Bradley Edward Briggs

Graduate Theses and Dissertations

Interest in substituting legumes for N fertilizer in beef cattle grazing systems has recently increased with rising fertilizer prices. Legumes are well known for their ability to fix atmospheric N and decrease dependence on input of N fertilizer. However, there are still difficulties associated with legume utilization including establishment and persistence. Two experiments were conducted to evaluate legume performance under herbivory. The objective of Experiment 1 was to compare forage production and beef cattle gains from annual ryegrass [Lolium multiflorum (L.)] and bermudagrass [Cynodon dactylon (L.) Pers.] pastures fertilized with N or overseeded with legumes. Gelbvieh × Angus …

Characterization And Consumer Acceptance Of White Striping In Broiler Breast Fillets, Vivek Ayamchirakkunnel Kuttappan

Graduate Theses and Dissertations

White striping is an emerging issue in the broiler meat industry which causes concerns among the producers. The condition is characterized by the occurrence of white striations, parallel to the direction of muscle fibers, mainly in broiler breast fillets and thighs. Fillets can be categorized as NORM (normal or no striping), MOD (moderate) and SEV (severe) depending on the degree of white striping. As a result of few previous research studies on the condition, there is no information available on the impact of white striping on the consumer acceptance and various meat quality attributes. Our hypothesis was that the occurrence …

Market Analysis Of Fresh Berries In The United States, Kristina Sobekova

Graduate Theses and Dissertations

This thesis contains a market analysis of fresh berries in United States. Specifically, it addresses strawberry, blueberry, blackberry and raspberry markets during 2008-2011. A double log model and the Almost Ideal Demand model are used to gain insight into the demand side of the market. An equilibrium displacement model is used to develop suggestions for producers and decision makers. The results demonstrate that retail demand for berry crops is elastic and that the different berries are substitutes for one another. The equilibrium displacement model is used to predict producer surplus changes to industry wide efforts aimed at both production efficiencies …

The Role Of Antioxidant Rich Berries In The Prevention Of Postmenopausal Bone Loss, Lydia Karimi Kaume

Graduate Theses and Dissertations

Postmenopausal osteoporosis is the most prevalent form of osteoporosis and results in fragility fractures. Smoking is one of the major risk factors for osteoporosis and is known to aggravate bone loss in postmenopausal women due to increased oxidative stress and inflammation. Diet-based interventions using berries have shown bone protective affects in animal studies partially due to antioxidant and anti-inflammatory properties of their phenolic compounds. The goal of this research was to determine the effects of antioxidant-rich fruits in the prevention of postmenopausal bone loss. Our first study examined the dose dependent effects of blackberries in preventing bone loss in an …

Evaluation Of Prebiotic Fibers And Pectin On Probiotic Strains And Effect Of Bacteriocin-Like Substance On The Survival Of Listeria Monocytogenes, Dolar Pak

Graduate Theses and Dissertations

Probiotics and prebiotics have been shown to provide beneficial effects on the host health and there are numerous research efforts being conducted on a variety of specific applications. However, most prebiotic carbohydrates are lower molecular weight oligosaccharides; and the health benefits of higher molecular weight pectins have not been fully evaluated. According to reviews, pectins are fermented in the large intestine due to the cooperative activities of colonic bacteria with complementary enzymatic activities. There are very few studies that demonstrate the fermentability of high methoxy pectin and low methoxy pectin by pure cultures of human isolates or probiotic bacteria. Thus, …

An Analysis Of The Redox Properties And Stability Of Chlamydomonas Reinhardtii Cytochrome F, Cytochrome C6, And Mutants Thereof, Nicole Lynn Vanderbush

Graduate Theses and Dissertations

This body of work presents mutagenesis studies conducted on two c-type cytochromes from Chlamydomonas reinhardtii. Cytochrome f, a unique c-type cytochrome, is investigated in regards to its redox potential, the dependence of the redox potential, and the thermal stability of the protein. The mutations made were Y1F, Y9F, Y160F, Y160L, R156L, and R156K. The residues that were mutated surround the heme. It was found that, relative to the wild-type, only the Y160L and R156 mutants showed any difference in midpoint potential at pH 7. Wild-type and mutants both had a midpoint potential that was dependent upon pH indicating that none …

Cell Bioenergetics In Leghorn Male Hepatoma Cells And Immortalized Chicken Liver Cells In Response To 4-Hydroxynonenal Induced Oxidative Stress, Alissa Laura Piekarski

Graduate Theses and Dissertations

Bioenergetic mechanisms responsible for ATP production are essential in carrying out maintenance and cell-specific functions. In this study, hepatocytes (liver cells) were used to test both endogenous and exogenous stress on cellular respiration. The secondary lipid peroxide, 4-hydroxynonenal (HNE), was used because it alters bioenergetics by increasing mitochondrial proton leak that attenuates mitochondrial radical production and, therefore, endogenous oxidative stress. The major objective of this study was to demonstrate effects of HNE-induced oxidative stress on avian hepatocyte bioenergetics. Various chemical which help enable the determination of oxygen (O2) consumption linked to ATP synthesis (oligomycin), maximal O2 consumption (FCCP), and proton …

Genetic Diversity, Pathogenicity/Virulence Variation And Population Structure Of Rhizoctonia Spp. Associated With Rice Sheath Blight In Arkansas And Qtl Mapping For Disease Resistance, Vanina Lilian Castroagudin

Graduate Theses and Dissertations

Rice sheath blight (ShB) is one of the most prevalent diseases in rice. The significance of this disease is increasing due to more intensive production practices globally. Rhizoctonia solani Kühn AG 1 - IA [teleomorph: Thanatephorus cucumeris (A.B. Frank) Donk] is considered the primary ShB pathogen of rice. However, Rhizoctonia oryzae-sativae, Rhizoctonia oryzae, and R. solani AG 2 and AG 11, have also been isolated from sheath blight-like lesions on rice.Up to now, there is little information on genetic diversity and patterns of molecular evolution of the fungus, and there is no study on the structure of the R. solani …

Superfund Evaluation: The Families Of Tar Creek, Gary D. Wilson

Graduate Theses and Dissertations

The Tar Creek Superfund Site is located in far northeastern Oklahoma near the Oklahoma/Kansas border in Ottawa County. The Site generally consists of a forty-square-mile area which is also part of the larger Tri-State Mining District that includes areas of Kansas and Missouri. The Site includes parts of five communities: Picher, Cardin, Quapaw, North Miami, and Commerce in Oklahoma. It also includes Treece, Kansas, and affects a total population of roughly 30,000 residents. Following Superfund designation, families in the Tar Creek area had to decide whether to accept or reject buy-out offers. This project explored the decision-making processes employed by …

The Evolution Of Natural Plant Communities Through Crop Migration And Crop-To-Weed Gene Flow, Meredith G. Schafer

Graduate Theses and Dissertations

With the rising demand for food and biofuels, the efficiency of crop production has become vital to assuring food security. Genetically engineered (GE) crop varieties are broadly thought to be a solution for improving the efficiency of crop production, but concerns regarding their release have heightened as more discoveries have focused on the influence of genetically engineered crops on native and weedy plant species. Risk assessment of GE crop varieties focuses on two main areas: feralization of crop systems and crop-weed hybridization. Risks include naturalization, transgene introgression, and the formation of novel genotypes in natural systems. In this study, roadside …

Consumer Sensory Preferences And Willingness-To-Pay For Nutraceutical-Rich Fruit, Lydia Lawless

Graduate Theses and Dissertations

Health-oriented juices are prime candidates for the nutraceutical market due to their inherent healthfulness and convenience. Fruits such as açaí berries, blueberries, blackberries, black cherries, Concord grapes, cranberries, and pomegranates are rich in potentially health-supporting polyphenolics, which makes the juices of these fruits attractive for nutraceutical optimization. The compositional, sensory, and stability properties of blueberry, blackberry, and Concord grape juice blends were explored in an extended shelf-life study. Initially, 100% blueberry juice had the highest total monomeric anthocyanins (67.40 mg/100mL), 100% blackberry juice had the highest total phenolics (249.24 mg/100mL), and 100% Concord juice had the highest polymeric color (23.21%). …

A Reexamination Of The Eastern Collared Lizard (Crotaphytus Collaris Collaris) In Arkansas, Ashley A. Grimsley

Graduate Theses and Dissertations

Loss of suitable habitat is a threat to species worldwide. Habitat destruction, including loss, change, and fragmentation of habitat, is the leading cause of species extinction. Eastern collared lizards (Crotaphytus collaris collaris) are habitat specialists on glades. Both C. c. collaris and glade habitats are rare and of special concern in the state of Arkansas. Many glade populations have already been extirpated in the Ozarks of Arkansas and Missouri. Increasing knowledge of the distribution, habitat structure, and population dynamics of C. c. collaris is important to ensure the survival of this species in Arkansas.

A literature review of …

Single-Pass Drying Of Rough Rice Using Glass Transition Principles, George Owira Ondier

Graduate Theses and Dissertations

The objective of this research was to study the drying characteristics, milling quality, and functional properties of rough rice subjected to single-pass drying while controlling kernel material states. Drying experiments were conducted at 60, 70, and 80C and relative humidities ranging from 13 to 83%. High drying air relative humidities (greater than 63%) maintained both the kernel surface and core in a rubbery state during drying, whereas low drying air relative humidities caused rapid transitioning of the surface layers from a rubbery to a glassy state. Long-grain pureline cultivar, Wells, medium-grain pureline cultivar, Jupiter, and long-grain hybrid cultivar, CL XL729, …

The Potential Environmental Benefits Of Hybrid Rice Varieties, Haxhire Myrteza

Graduate Theses and Dissertations

With water insufficiency being already a major issue and potential carbon policies on greenhouse gas (GHG) emissions, Arkansas rice producers may need to undergo some changes in regards to rice cultivar selection. The purpose of this study is to estimate the environmental benefits of cultivating hybrid rice varieties as opposed to conventional and Clearfield rice varieties. To accomplish this goal, water use and GHG emissions were estimated on per acre (ac) and per bushel (bu) basis for most commonly cultivated rice varieties in Arkansas. The study focuses particularly on six main rice stations in the State of Arkansas. The hypothesis …

The Identification Of Quantitative Trait Loci For Sucrose And Stachyose Content In Soybean Seed, Ailan Zeng

Graduate Theses and Dissertations

Sucrose is a desirable sugar in soybean seed that affects the quality and taste of soyfoods, while stachyose is a non-digestible sugar that induces flatulence in non-ruminant animals. Therefore, soybean cultivars with high sucrose and/or low stachyose would be valuable for soyfood and meal markets. The objectives of this study were to identify quantitative trait loci (QTL) or genes associated with seed sucrose and stachyose content using simple sequence repeat (SSR) or single nucleotide polymorphism (SNP) markers. A low sucrose line, MFS-553, was crossed with a high sucrose plant introduction, PI 243545, to develop the sucrose QTL mapping population. A …

Part I - A Study Of The Formation Of Carbenes By Elimination Of Α-Bromosilanes And Application Toward The Synthesis Of Transition Metal Complexed Quinone Methide Analogs. Part Ii - Development Of Novel 7-Membered Ring Carbene Ligands For Palladium Catalyzed Cross Coupling Reactions., Christian Michael Loeschel

Graduate Theses and Dissertations

In part I, we wish to report our approaches toward transition metal complexed ortho-quinone methide analogs. ortho-Quinone Methides are a class of highly reactive compounds with a wide range of chemical and biological applications. Previously, a stable iron complexed benzannulated 5-membered ring quinone methide analog was reported by Allison and Neal27. Herein, we report our approaches to improve the reactivity of that system by removing benzannulation as well as changing the metal from iron to manganese and rhenium.

Furthermore, a methodological study on generating carbenes under mild conditions by elimination of α-halosilanes and its application towards metal complexed quinone methide …

Impact Of Hybrid Rice On Food Security: A Spatial Equilibrium Analysis Of Global Adoption And Diffusion Of Hybrid Rice Varieties, Till Ludwig

Graduate Theses and Dissertations

Rice is the staple crop for most consumers in Asia. More than half of the global population depends on rice. However, scarce resources for agricultural production and unfavorable conditions will make it hard to meet future demand in rice and threaten future food security. Hybrid rice technology is a method to increase the productivity of resources needed for rice production. Current developments show not only yield improvements in comparison to existing conventional and hybrid varieties, but also fuel hopes for new abiotic and biotic stress tolerance. The objective of this study is to determine what impact hybrid rice varieties can …