Botany Commons^™

Available Nitrogen And Denitrification In Soil Altered By Ground Cover And Nutrient Source In An Organic Apple Orchard, Jade Nicole Ford

Graduate Theses and Dissertations

A shift in public demand towards more organic and locally produced fruit and vegetables has been occurring across the United States in recent years. A common practice in organic fruit production is the application of organic ground covers to supply nutrients while enhancing other soil properties. A need for research exists in the southern region of the U.S. examining the effects of regionally applicable ground cover and nutrient management on nitrogen availability and the microbial community to provide information to organic farmers in the region. Two studies were conducted to determine how 12 treatment combinations of four ground covers (compost, …

Defining The Potassium Nutritional Requirements And Distribution Among Plant Parts Of Representative Soybean Cultivars From Different Maturity Groups, Md. Rasel Parvej

Graduate Theses and Dissertations

The potassium (K) requirement of soybean [Glycine max (L.) Merr.] was investigated to determine whether cultivar sensitivity to K deficiency was affected by growth habit (determinate or indeterminate) and how cultivars from each growth habit accumulate and distribute K among plant structures. We also diagnosed K deficiency across reproductive growth stages (R2-6) using trifoliolate leaf- and petiole-K concentrations and at harvest (R8) using seed-K concentration. Soybean responded similarly to K deficiency in terms of yield, selected yield components, and seed-K concentration, regardless of growth habit. The yield loss from K deficiency was greatest on the middle to upper nodes of …

Validation Of Soil-Test-Based Phosphorus And Potassium Fertilizer Recommendations For Rice And Soybean, Matthew Scott Fryer

Graduate Theses and Dissertations

The science of soil-testing for nutrient management and fertilizer recommendations is widely accepted among scientists and agronomists. Although this science is unsurpassed in predicting soil nutrient availability, soil-test interpretations are seldom validated. Major research objectives for irrigated soybean [Glycine max (L.) Merr.] and direct-seeded, delayed-flood rice (Oryza sativa L.) were to: i) validate the accuracy of Mehlich-3 soil-test P (STP) and K (STK) interpretations and ii) published critical tissue-P and -K interpretations in predicting the yield response to fertilizer at different significance levels (p≤0.05 to 0.25), iii) examine how seed nutrient concentrations are influenced by fertilization and crop response to …

Investigations Of Ethylene And Ethylene Inhibition, Ball Lie, And Synthetic Turf Color, William Daniel Strunk

Graduate Theses and Dissertations

This dissertation is comprised of several studies over three unrelated areas of focus. Chapters two and three investigate the role of the hormone ethylene on growth of creeping bentgrass through (1) exposure of turf to exogenous ethylene and (2) testing an ethylene inhibiting compound for use to alleviate stress related injury. Previous research demonstrated a correlation of stress injury and ethylene and lessening of injury through ethylene inhibition, but little work has been conducted evaluating the direct effects of ethylene. These studies failed to confirm findings in previous research. Chapters four and five aim to illustrate the impact of turfgrass …

Alliaria Petiolata (M.Bieb.) Cavara & Grande [Brassicaceae], An Invasive Herb In The Southern Ozark Plateaus: A Comparison Of Species Composition And Richness, Soil Properties, And Earthworm Composition And Biomass In Invaded Versus Non-Invaded Sites, Jennifer D. Ogle

Graduate Theses and Dissertations

Invasive species are widely recognized as organisms that severely alter ecosystem processes in the habitats to which they are introduced. Alliaria petiolata is one of the most important invasive plants in forests of the northern United States. This study examined the geographic distribution of the plant in the southern Ozarks, as well as the effect that it may be having on natural processes within forests of the region by comparing plant species richness, plant cover, and soil properties in invaded and non-invaded plots. It was found that A. petiolata is not significantly altering species richness, cover, or soil properties in …

Nutrient Management For Growing Dandelion (Taraxacum Officinale L.) In Nutrient Film And Deep Flow Hydroponics, Reetinder Gill

Graduate Theses and Dissertations

This research study was conducted to determine an optimal nutrient strategy for dandelion production in nutrient film technique (NFT) and deep flow technique (DFT) systems of hydroponics. It was achieved by growing dandelion at varying levels of nutrient solution concentration and pH in both NFT and DFT systems. Additionally, an optimal nutrient solution concentration and timing of application for dandelion seedling production was also determined.

A Microhabitat Assessment Of Five Species Of Invasive Plants In The Ozarks And Appalachians, Eric Hearth

Graduate Theses and Dissertations

Invasive species present a threat to native communities and their introduction and expansion can alter community structure and dynamics. Multiple approaches can be employed for invasive species management including prevention and detection. In this study, microhabitat assessments were conducted on colonies of five species of invasive plants, Alliaria petiolata (M. Bieb.) Cavara & Grande, Lespedeza cuneata (Dum. Cours.) G. Don, Lonicera japonica Thunb., Microstegium vimineum (Trin.) A. Camus, and Rosa multiflora Thunb. in the Ozark Plateau and Appalachians. Elevation, soil moisture, soil pH, light ratio, slope, aspect, distance to disturbance, as well as soil nutrient levels were recorded for each …

The Mechanism Of Lhcp Insertion Into Thylakoid Membranes, Larae Brown

Graduate Theses and Dissertations

The light harvesting chlorophyll a/b-binding proteins (LHCPs) are the most abundant membrane proteins. LHCP is a nuclear encoded protein which is targeted to the thylakoid membranes by chloroplast signal recognition particles (cpSRP). Insertion into thylakoid membranes is facilitated by the cpSRP receptor cpFtsY and the Alb3 translocase. Work here focused on understanding the molecular events of LHCP insertion into the thylakoid membranes. Specifically, we sought to develop a tool to detect the insertion of the lumen-localized loop of LHCP into thylakoid membranes, which relies on cleavage of the loop by a thylakoid lumen processing protease. We also sought to understand …

Habitat Assessment Of Two Narrowly Endemic Plant Species, Ozark Spiderwort (Tradescantia Ozarkana) E. S. Anderson And Woods. And Newton's Larkspur (Delphinium Newtonianum) D. M. Moore, Autumn Lynn Coffey Olsen

Graduate Theses and Dissertations

The threat of biodiversity loss is upon us with the onset of climate change and our ever-demanding needs of the Earth's resources for a rapidly growing human population. Species highly vulnerable to loss are those limited in abundance and distribution, or those with reduced genetic diversity. Efforts to actively conserve a sensitive species require effectual data on the probable causes of their vulnerability. Two species of concern, Delphinium newtonianum and Tradescantia ozarkana, are globally rare endemic vascular plant species found only in the Interior Highlands of North America. In an attempt to understand the causes for their endemism, habitat …

A Comparison Of Milled Rice Fissuring Kinetics Of Hybrid And Pureline Cultivars, Semehar Haile Tesfaye

Graduate Theses and Dissertations

Over the past decade, the use of hybrid rice cultivars has greatly increased, and this has led to questions about the processing behavior of hybrid cultivars. This study compares the milled rice fissuring kinetics of hybrid and pureline cultivars. Also, this study elucidates the effects of kernel type (long-grain vs. medium-grain rice cultivars), surface lipid content (SLC), and kernel thickness on fissuring rates.

Three hybrid (CL XL745, CL XL729 and XL753) and five pureline (Wells, CL151, Cheniere, Jupiter and CL261) cultivar lots were procured. Jupiter and CL261 are medium-grain cultivars, whereas the rest are long-grain cultivars. Two experiments were conducted. …

Study Of Thermotolerance Mechanism In Gossypium Hirsutum Through Identification Of Heat Stress Genes, Jin Zhang

Graduate Theses and Dissertations

ABSTRACT

Heat stress causes major losses to cotton seed and lint yield. Introduction of heat stress tolerance to Arkansas cotton varieties is highly desirable. However, very little is known about the molecular basis of heat stress tolerance in cotton. The present study attempted to identify heat stress tolerance genes in two heat-tolerant cotton cultivars, VH260 and MNH456, originating from Pakistan. Towards this, the expression profile of the cotton orthologs of sevenArabidopsisheat stress tolerance genes was studied in these two cultivars, and compared with the two heat-susceptible cotton cultivars, ST213 and ST4288, originating from Mississippi Delta region. In addition, physiological parameters …

The Biological Control Of Spotted Knapweed In The Southeastern United States, Carey R. Minteer

Graduate Theses and Dissertations

Spotted knapweed is an invasive, short-term-perennial plant that is native to Eurasia. It was accidentally introduced into North America in the early 1890's and has since spread across The United States and Canada. Spotted knapweed degrades rangelands and pastures by negatively impacting native plants, increasing soil surface runoff and stream sediment yields, and reducing soil infiltration. A biological control program for spotted knapweed using Larinus minutus (Coleoptera: Curculionidae), was initiated in Arkansas in 2008. In this dissertation I described the releases of L. minutus and investigated the adult activity in the southeastern United States (Chapter 1), investigated the effects of …

Characterization And Epidemiology Of Soybean Vein Necrosis Associated Virus, Jing Zhou

Graduate Theses and Dissertations

Soybean vein necrosis disease (SVND) is widespread in major soybean-producing areas in the U.S. The typical disease symptoms exhibit as vein clearing along the main vein, which turn into chlorosis or necrosis as season progresses. Double-stranded RNA isolation and shot gun cloning of symptomatic tissues revealed the presence of a new tospovirus, provisionally named as Soybean vein necrosis associated virus (SVNaV). The presence of the virus has been confirmed in 12 states: Arkansas, Illinois, Missouri, Kansas, Tennessee, Kentucky, Mississippi, Maryland, Delaware, Virginia and New York. Symptomatic samples collected from eight states (AR, IL, MO, MS, KS, TN, MD and DE), …

Meta-Analysis Of Wheat Qtl Regions Associated With Heat And Drought Stress, Marlovi Andrea Acuna Galindo

Graduate Theses and Dissertations

Heat and drought are the two most important environmental constraints to wheat production globally, are often present simultaneously and will become more severe with global climate change. This presents a unique challenge to wheat scientists who must work to develop wheat cultivars that are productive and adapted to future environmental conditions. A number of recent studies have reported quantitative trait loci (QTL) associated with heat and drought tolerance, as well as QTL for stress adaptive traits such as the availability of stem carbohydrates or crop canopy temperature. The objective of this study was to perform a meta-analysis of these QTL …

Evaluation Of The Recombination Efficiencies Of Flp Proteins, Linh Duy Nguyen

Graduate Theses and Dissertations

Site-specific recombination systems are powerful tools for genetic modification. They have been used to integrate a transgene into a pre-defined locus and to remove marker genes from a transgene locus. Two of the most widely used site-specific recombination systems in plants are the Cre/lox system from the bacteriophage P1 and the FLP/FRT system from the yeast Saccharomyces cerevisiae. The Cre/lox system is well-characterized and is the first choice in application of site-specific recombination system. However, some applications such as marker-free site-specific gene integration require the use of two recombination systems. In addition, the availability of alternative recombination systems can offer …

Effect Of Water-Deficit Stress On Cotton During Reproductive Development, Dimitra Loka

Graduate Theses and Dissertations

Water deficit is a major abiotic factor limiting plant growth and crop productivity around the world. Cotton (Gossypium hirsutum L.) is considered to be relatively tolerant to drought and the effects of water stress on leaf physiology and metabolism have been extensively documented. However, information is lacking on the effect of water-deficit stress on the cotton flower. It was hypothesized that water-deficit stress would impair gas exchange functions which consequently would result in perturbation of carbohydrates of cotton reproductive units. To investigate this hypothesis growth room studies and field studies were conducted with the objectives being to document the physiological …

Gene Expression And Physiological Analyses To Study Metabolic Shifts In Medicago Truncatula Subjected To Biotic Stresses, Michelle Ryan Martin

Graduate Theses and Dissertations

Plants are frequently under attack from pests and deploy various defense mechanisms to fight off predators. Many plant defenses are induced following herbivory or pathogen infection. An investment in defense could potentially lead to a diversion of metabolic resources away from primary metabolism, including reduction in plant commitment to photosynthesis. In this thesis, changes in expression levels of representative genes for primary and secondary metabolism were studied using real-time polymerase chain reaction (PCR) in Medicago truncatula Gaertner subjected to beet armyworm (Spodoptera exigua H¨¹bner) damage or Phoma medicaginis Malbr. & Roum. infection. Photosynthetic yield was also measured using chlorophyll fluorescence …

The Role Of Albino3 And The Lipid Environment In Chloroplast Signal Recognition Particle Targeting, Nathan Lewis

Graduate Theses and Dissertations

Signal recognition particles (SRPs) in pro- and eukaryotes function in cotranslational targeting of nascent poplypeptides to an SRP receptor at the target membrane. A unique chloroplast SRP (cpSRP) functions post-translationally to direct light-harvesting chlorophyll-binding proteins (LHCPs) to the receptor cpFtsY at the thylakoid membrane for LHCP insertion in a process involving the integral membrane protein Albino3 (Alb3) and requiring GTP. Work here focuses on understanding cpSRP targeting events at the thylakoid membrane, specifically those involving Alb3 and the lipid environment.

We show an interaction between the novel cpSRP subunit cpSRP43 and the soluble, stromal-exposed C terminus of Albino3 (Alb3-Cterm). We …