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Using Koch’S Postulate To Identify The Causative Agent Of Dieback In Malosma Laurina During Historic Drought In California, Adriana J. Borges, Emily R. Pierce, Mariah K. Taylor, Frida J. Morales

Featured Research

Coastal Southern California has a Mediterranean-type climate, meaning that it experiences warm, dry summers and cool, wet winters. Recently, California has been experiencing an unprecedented drought, possibly as a result of climate change. Malosma laurina is a typically hearty chaparral plant is known for being resistant to drought due to its deep rooting depth, but even it is being negatively affected by drought and is experiencing dieback. Some of this dieback is caused by a Botryospharae fungal infection, which blocks xylem conduits and stops water flow through the plant. With a looming El Niño, this study seeks to understand the …

Genetic Determinism Of Xanthomonas Arboricola Pv. Pruni (Xap) Resistance, Fruit Quality, And Phenological Traits In Peach And Incorporation Of Marker-Assisted Selection (Mas) In The University Of Arkansas Peach And Nectarine Breeding Program, Terrence James Frett

Graduate Theses and Dissertations

For over two decades the incorporation of marker-assisted selection (MAS) has been discussed as an innovative approach to increase peach breeding efficiency. Although hundreds of quantitative trait loci (QTLs) have been identified, only a few have been converted into usable MAS tools. This highlights a disconnect between genomic discoveries and practical application in breeding programs, which has delayed use of MAS.

In this dissertation, three sequential steps were performed with the objective to bridge this gap and develop breeding-relevant DNA tests for MAS of fruit bacterial spot resistance (Xap1 and Xap6), fruit quality [blush (Rf), acidity (D), and acidity and …

Establishment And Trends In Persistence Of Selected Perennial Cool-Season Grasses, Craig W. Rigby

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The choice of plant materials is an important factor in restoration or revegetation of disturbed rangelands. To better identify plant materials that could be adapted to increased competition from invasive grasses and fluctuations in temperature and precipitation, there is a need to understand potential seedling establishment, plant persistence, and dry-matter yield (DMY) as a measure of plant vigor in the newly developed varieties across a wide range of environmental conditions. Experiments were conducted on four semiarid range sites to compare these traits in 14 perennial cool-season grass species currently used for revegetation in the Western U.S.A. There were location differences, …

Agricultural Nitrogen Management Affects Microbial Communities, Enzyme Activities, And Functional Genes For Nitrification And Nitrogen Mineralization, Yang Ouyang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Improved understanding of nitrogen cycling in agriculture is essential for increasing fertilizer use efficiency and sustainable food production. The availability and mobility of nitrogen are largely determined by the processes of nitrogen mineralization and nitrification. Nitrification is mediated by ammonia oxidizing bacteria, ammonia oxidizing archaea, and nitrite oxidizing bacteria. Our understanding of the controls on the relative activity of these nitrifying organisms in soil is limited. A wide variety of soil microorganisms produce enzymes that mineralize nitrogen from organic matter, but we have limited knowledge about links between enzyme activity and the microbes that work in soil. The main objective …

Impairing The Insect Immune System With Plant-Derived Substances, Katherine Haszcz

Graduate Theses/Dissertations

Worldwide resistance to current insecticides continues to grow at an alarming rate, with the danger of pesticide overuse reducing acceptable doses. Alternative strategies for insect pest management are therefore imperative. By compromising the insect immune system with plant-derived substances and studying the detailed processes involved in hemocyte-mediated responses, one can develop improved methods for insect control. Hemocyte numbers change in response to stress. This allows essential defense mechanisms such as phagocytosis and encapsulation to take place. In this thesis, plant-derived substances were used to challenge larval-stage Galleria mellonella (Family: Lepidoptera) due to their nontoxic nature and high value in pest …

Investigation Into The Genetic Basis Of Leaf Shape Morphology In Grapes, Brigette Rachelle Williams

Graduate Theses/Dissertations

Leaves are a highly distinguishing characteristic in grape (Vitis vinifera) and display great diversity in comparison to other crops. However, little is known about the genetic basis of leaf shape in grape. Here, morphometrics and 40,724 single-nucleotide polymorphisms (SNPs) are correlated to describe the relationship between genotype and phenotype of leaf shape in grape. Parent vines (Norton and Cabernet Sauvignon) and their F1 progeny make up the mapping population located at the State Fruit Experiment Station, Genomics Research Vineyard on Missouri State University campus in Mountain Grove, Missouri. Important leaf shape characteristics (n=17) were identified based on the venation pattern, …

Effects Of Abscisic Acid (Aba) On Germination Rate Of Three Rangeland Species, Turmandakh Badrakh

Theses and Dissertations

Seeds sown in the fall to restore sagebrush (Artemisia spp.) steppe plant communities could experience high mortality when they germinate and seedlings freeze during the winter. Delaying germination until the risk of frost is past could increase seedling survival. We evaluated the use of abscisic acid (ABA) to delay germination of Elymus elymoides, Pseudoroegneria spicata, and Linum perenne. The following treatments were applied: uncoated seed, seed coated with ABA at 2.2, 4.4, 8.8, 13.2, and 17.6 g of active ingredient kg-1 of seed, and seed coated with no ABA. The influence of seed treatments on germination were tested at five …

Nebline, May 2016

NEBLINE Newsletter Archive from Nebraska Extension in Lancaster County

Feature: Emerald Ash Borer is Getting Closer

Food & Health

Family Living

Farm & Acreage

Horticulture

Pests & Wildlife

4-H & Youth

Extension Calendar

and other extension news and events

Maize, Switchgrass, And Ponderosa Pine Biochar Added To Soil Increased Herbicide Sorption And Decreased Herbicide Efficacy, Sharon A. Clay, Kaitlynn K. Krack, Stephanie A. Bruggeman, Sharon Papiernik, Thomas E. Schumacher

Agronomy, Horticulture and Plant Science Faculty Publications

Biochar, a by-product of pyrolysis made from a wide array of plant biomass when producing biofuels, is a proposed soil amendment to improve soil health. This study measured herbicide sorption and efficacy when soils were treated with low (1% w/w) or high (10% w/w) amounts of biochar manufactured from different feedstocks [maize (Zea mays) stover, switchgrass (Panicum vigatum), and ponderosa pine (Pinus ponderosa)], and treated with different post-processing techniques. Twenty-four hour batch equilibration measured sorption of ¹⁴C-labelled atrazine or 2,4-D to two soil types with and without biochar amendments. Herbicide efficacy was measured …

Greater Bud Outgrowth Of Bromus Inermis Than Pascopyrum Smithii Under Multiple Environmental Conditions, Jacqueline P. Ott, Jack L. Butler, Yuping Rong, Lan Xu

Natural Resource Management Faculty Publications

Tiller recruitment of perennial grasses in mixed-grass prairie primarily occurs from belowground buds. Environmental conditions, such as temperature, soil moisture and grazing can affect bud outgrowth of both invasive and native perennial grasses. Differential bud outgrowth responses of native and invasive species to climate change and grazing could alter competitive interactions that have implications for future land management. The aims of this work were to (i) compare how spring temperature altered bud outgrowth of native Pascopyrum smithii (Rydb.) Á. Löve (western wheatgrass) and introduced Bromus inermis Leyss.(smooth brome), (ii) compare how watering frequency altered bud outgrowth of these two species …

Spinach (Spinacia Oleracea L.) Seed Germination And Whole Plant Growth Response To Heat Stress And Association Mapping Of Bolting, Tallness And Erectness For Use In Spinach Breeding, Jessica Chitwood

Graduate Theses and Dissertations

The effect of temperature on spinach seed germination was evaluated using a total of nine spinach genotypes and seven temperatures: 10, 15, 20, 25, 30, 32, and 35 oC in growth chambers. Genetic variation was observed. ‘Donkey’, ‘Marabu’, and ‘Raccoon’ showed higher seed germination percentage with over 70% at 30 and 32 oC, indicating the three spinach genotypes had heat-tolerance for germination. However, all spinach genotypes except ‘Ozarka II’ had lower germination percentages of less than 30% while ‘Ozarka II’ had 63% at 35 oC, indicating ‘Ozarka II’ may be a source of heat-tolerance for seed germination.

Seed germination may …

The Frugal Innovator: Creating Change On A Shoestring Budget, Charles Leadbeater

Asian Management Insights

The world needs innovation that is lean, simple, clean and social.

A Preliminary Study On The Role Of Enhancer Of Flavonoid Production (Efp) In Flavonoid Biosynthesis, Jia Guo

Honors Scholar Theses

Flavonoids are involved in a variety of biological roles ranging from pathogen protection, pigment intensity, antioxidant effects, and even prevention from cancer or cardiovascular diseases. Because of the diverse and beneficial functions that flavonoids have, the flavonoid biosynthetic pathway has been well studied. Recently, a gene called the Enhancer of Flavonoid Production (EFP) was discovered when mutations in this gene caused the Japanese morning glory flowers to exhibit a pale-colored phenotype. Although EFP is known to increase flavonoid production, the direct mechanism to how EFP enhances enzymes in the flavonoid biosynthetic pathway has yet to be discovered. It …

Intraspecific Variation In The Response Of Elymus Elymoides To Competition From Bromus Tectorum, Rebecca K. Mann

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the western United States, thousands of acres of degraded rangelands are dominated by aggressive invasive species such as cheatgrass (Bromus tectorum), and are seeded by managers with native plants in an attempt to restore species diversity, wildlife habitat, and ecosystem services. There are many options for obtaining seeds of native plants; for instance, they can be collected from the region where restoration is to occur, or they may be purchased through commercial producers. For a given plant species, managers may also select seeds from unique subspecies, cultivars, and populations. Genetic differentiation among these within-species groups can not only affect …

Gene Expression And Physiological Analysis To Study Differences Between Oryza Sativa Cultivars Susceptible And Resistant To Chalky Grain Formation Subjected To High Nighttime Temperatures., Nicholas Lawson

Graduate Theses and Dissertations

Starch composition and grain quality of rice is greatly influenced by genotype and environmental factors. The detrimental effects of high nighttime temperatures on rice yield and quality has recently become apparent, with some of the warmest average nighttime temperatures being recorded in the past few years. One of the most notable effects of this stress, an increase in grain chalk formation, correlates with a decrease in quality. This effect varies greatly between cultivars as some show less temperature-sensitive quality reduction than others. The goal of this research is to elucidate fundamental changes that occur in developing plants and grains as …

Identification Of N-Acylethanolamine Hydrolyzing Enzyme In Solanum Lycopersicum, Derek A. Stuffle

Undergraduate Honors Theses

N-acylethanolamines (NAEs) are fatty acid derivatives that occur naturally in plant and animal systems. In mammals, they regulate physiological functions, including neurotransmission, immune responses, vasodilation, embryo development and implantation, feeding behavior, and cell proliferation. NAEs are metabolized by fatty acid amide hydrolase (FAAH), which belongs to the amidase signature family. It is hypothesized that putative FAAH functions as the catalyst in the metabolism of N-acylethanolamine in tomato plants. To test the hypothesis, FAAH protein homologs were identified in tomato via in silico analysis. Among the six homologs identified, FAAH1 and FAAH2 were selected for further validation. This study …

The Role Of Cellulose Synthase-Like D Genes In Tip Growth Of Physcomitrella Patens, Erin E. Killeavy, Arielle Chaves, Alison Roberts

Senior Honors Projects

Physcomitrella patens is a non-vascular plant with a relatively small genome and is amongst the few eukaryotic organisms that have a high rate of homologous recombination. This is valuable in biological research because it allows for targeted genetic modification of the organism. In vascular plants like Arabidopsis thaliana, a model organism, Cellulose Synthase-like D (CSLD) genes have been discovered to be important in tip growth. This type of growth is observed in the pollen tubes and root hairs of these plant types. The CSLD genes in Arabidopsis were found to play a crucial role in the growth of …

A Bioinformatics Approach To Addressing The Responses Of Rice Aleurone Cells To Hormones Abscisic Acid And Gibberellic Acid, Kenneth Arthur Watanabe

UNLV Theses, Dissertations, Professional Papers, and Capstones

The hormone abscisic acid (ABA) is biosynthesized by higher plants in response to various abiotic stresses such as drought and antagonizes the growth and germination-promoting hormone gibberellic acid (GA). The seed is a model system for studying desiccation tolerance and germination. The thin layer of cells surrounding the seed, the aleurone layer, plays a direct role in seed germination and an indirect role in desiccation tolerance. The goal of my research is to address the molecular mechanism underlying the responses of rice aleurone cells to ABA and GA, by taking a genomics approach. An accurate and complete annotation of the …

Vascular Flora Of The Possum Walk Trail At The Infinity Science Center, Hancock County, Mississippi, Hanna M. Miller

Honors Theses

The North American Coastal Plain contains some of the highest plant diversity in the temperate world. However, most of the region has remained unstudied, resulting in a lack of knowledge about the unique plant communities present there. This flora catalogues the vascular plant species along the Possum Walk Trail on the southeast corner of the Infinity Science Center in Hancock County, Mississippi. Additionally, interpretive signs have been developed to display information about engaging species and phenomena to increase public interest in native plant life and involve them conservation efforts. The site was surveyed from spring of 2015 to spring of …

Screening Strawberry Clones For Anthracnose Disease Resistance Using Traditional Techniques And Molecular Markers, Melinda A. Miller-Butler

Dissertations

Cultivated strawberry, Fragaria x ananassa Duchesne, is host for many pathogens. One of the most destructive diseases of strawberry is anthracnose, whose symptoms include fruit rot, leaf and petiole lesions, crown rot, wilt, and death. Three species of Colletotrichum are considered causative agents of anthracnose diseases of strawberry. Colletotrichum acutatum causes anthracnose fruit rot, has a broad host range, and occurs in most areas of the world where strawberries are grown. Colletotrichum fragariae, the primary causal fungus of anthracnose crown rot, may infect all aboveground parts of the strawberry plant, and has restricted host and geographic ranges. Colletotrichum gloeosporioides …

Friend Or Foe—Light Availability Determines The Relationship Between Mycorrhizal Fungi, Rhizobia And Lima Bean (Phaseolus Lunatus L.), Daniel J. Ballhorn, Martin Schädler, Jacob D. Elias, Jess A. Millar, Stefanie Kautz

Biology Faculty Publications and Presentations

Plant associations with root microbes represent some of the most important symbioses on earth. While often critically promoting plant fitness, nitrogen-fixing rhizobia and arbuscular mycorrhizal fungi (AMF) also demand significant carbohydrate allocation in exchange for key nutrients. Though plants may often compensate for carbon loss, constraints may arise under light limitation when plants cannot extensively increase photosynthesis. Under such conditions, costs for maintaining symbioses may outweigh benefits, turning mutualist microbes into parasites, resulting in reduced plant growth and reproduction. In natural systems plants commonly grow with different symbionts simultaneously which again may interact with each other. This might add complexity …

Selenate Uptake By Symphyotrichum Ascendens Western Aster, Nathan Hankes

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Symphyotrichum ascendens is a native forb species responsible for selenium poisoning of livestock grazing on mine wastes in the American Intermountain West. While S. ascendens has long been assumed to be a Se accumulator species, this report details the first investigation into its Se uptake, affinity, partitioning, and growth in response to selenate fertilization. The study was performed in a hydroponic growth environment at selenate concentrations of 0.1, 0.25, 0.5, and 1.0 mM selenate. Symphyotrichum ascendens absorbed selenate in percentage concentrations, with the highest tissue concentration of 3.6% Se. Symphyotrichum ascendens exhibited signs of stress, producing 69.2% less biomass at …

Utah Lotus: North American Legume For Possible Use In Rangeland Revegetation In The Southern Great Basin Of The Western United States, Jason M. Stettler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This thesis project explored the production and forage quality characteristics of Utah lotus (Lotus utahensis Ottley) and scrub lotus (L. wrightii (A. Gray) Greene) seed collections during a two-year period. The variation of 14 Utah lotus and five scrub lotus seed collections was evaluated by measuring important plant characteristics at three common garden sites in northern Utah. In addition, the genetic structure of the collections was determined by molecular biological techniques. Large variation was observed among collections for all phenotypic traits measured, with Utah lotus and scrub lotus being phenotypically quite different. Two collections of Utah lotus (LU-5 …

Salt Tolerance Of Forage Kochia, Gardner's Saltbush, And Halogeton: Studies In Hydroponic Culture, Joseph Sagers

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Halogeton (Halogeton glomeratus) is a halophytic, invasive species that displaces Gardner’s saltbush (Atriplex gardneri) on saline rangelands. Forage kochia (Bassia prostrata) is a potential species to rehabilitate these ecosystems. This study compared the salinity tolerance of these species and tall wheatgrass (Thinopyrum ponticum) and alfalfa (Medicago sativa). Plants were evaluated for 28 days in hydroponics where they were maintained at 0, 150, 200, 300, 400, 600, and 800 mM NaCl. Shoot growth and ion accumulation were determined. Alfalfa and tall wheatgrass were severely affected by salt with both species’ shoot …

Increasing The Sustainability Of Utah Farms By Incorporating Quinoa As A Novel Crop And Protecting Soil Health, Kristine R. Buckland

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Most of the western United States faces increasing water shortages in the coming years, that will present a major challenge for maintaining sustainable farms. Incorporating an alternative crop that is well adapted to projected changes in climate could be a successful approach to increasing the sustainability of farms in the region. Quinoa, Chenopodium quinoa Willd., may be an ideal alternative crop to meet the demands of the Intermountain West. Before widespread adoption of this novel crop can occur, best management strategies need to be documented. This paper provides research on cropping systems, irrigation rates, and weed competition with quinoa. Additionally, …

Soil Nutrient Cycling And Water Use In Response To Orchard Floor Management In Stone-Fruit Orchards In The Intermountain West, Catherine Mae Culumber

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An organic peach orchard trial evaluated the effectiveness of different organic management approaches to enhance soil quality and conserve water without compromise to fruit tree growth and fertility. Two tree-row treatments: ‘straw mulch’ (Triticum aestivum L.) and ‘living mulch’ (Lobularia maritima (L.) Desv.) were tested in combination with two alleyway groundcovers: ‘grass’ (Festuca rubra L. with Lolium perenne L.) and a legume, ‘Birdsfoot trefoil’ (Lotus corniculatus L.). The novel treatments were compared with tillage and weed fabric tree-rows with grass alleyways. After mowing, cuttings from the trefoil alleyway were deposited into tree-rows, which provided additional N …

Growth And Productivity Of Irrigated Rice (Oryza Sativa L.) For A Tropical High Altitude Environment In Rwanda, Elie Rene Gasore

Graduate Theses and Dissertations

Yield components, grain yield, biomass and plant N accumulation, and N fertilizer responses of irrigated rice (Oryza sativa, L.) were evaluated for a tropical inland valley environment in the high altitudes in Rwanda. Effects were measured for nitrogen (N) fertilizer rate (0, 60, 90,120,150,180 kg N ha-1), season, growth stage and cultivar of different subspecies and plant types during 2012 dry season (DS) and 2013 wet season (WS) at Cyili Rice Research Farm (1380 m above sea level). Variations in irradiance (17.2± 0.32 MJ m-2 day-1 in DS and 9.4 ± 0.66 MJ m-2 day-1in WS) were linked to seasonal …

Genetic Analysis Of Soybean Mosaic Virus (Smv) Resistance Genes In Soybean [Glycine Max (L.) Merr.], Mariola Klepadlo

Graduate Theses and Dissertations

Soybean mosaic virus (SMV) causes the most serious viral disease in soybean worldwide. Seven SMV strains, G1 - G7, and three independent multi-allelic loci for SMV resistance, Rsv1, Rsv3, and Rsv4, have been identified. In the initial study, 299 soybean germplasm lines were genotyped for Rsv4 region, inoculated with SMV-G1 and G7 strains, and classified into several resistance groups. The Glyma.02g121400 locus was sequenced from ten soybean accessions, and alignment of the sequences revealed three SNPs displaying 100% polymorphic consistency when a soybean genotype carrying the Rsv4 gene was present. A cross between V94-5152 × Lee 68 was made to …

Geospatial Analysis Of Droughts, Rice And Wheat Production, And Agrarian Vulnerability: A District-Level Study Of The Self-Calibrated Palmer Drought Severity Index In India, Aaron Michael Shew

Graduate Theses and Dissertations

Droughts have affected more people than any other natural disaster in the last century, causing billions in economic damages and millions of deaths. As the Sea Surface Temperatures (SST) have heated in the Indian Ocean, drought patterns across South Asia have changed; the Indian monsoon has become more volatile and less predictable. In this study, monthly self-calibrated Palmer Drought Severity Index (sc-PDSI) data for the time period between 1950 and 2009 were interpolated to India’s districts; then the data were analyzed for changes in frequency and severity. The data were further evaluated using Anselin’s Local Moran’s I Statistic to elicit …

Preserving Rice Quality: Fine-Mapping And Introgressing A Fissure Resistance Locus, Haley Marie Sater

Graduate Theses and Dissertations

Rice (Oryza sativa L.) kernel fissuring is a major concern of both rice producers and millers. Fissures are small cracks in rice kernels that increase breakage of kernels when milled, and decrease the value of processed rice. This study employed molecular gene tagging methods to fine-map a fissure resistance (FR) locus found in ‘Cybonnet’, a semidwarf tropical japonica cultivar, as well as transfer this trait to rice genotypes of taller, non-semidwarf plant height that are better adapted to some rice production systems. Three QTLs for FR were previously reported; the FR locus with strongest effect resides near the semidwarf sd-1 …