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Investigating The Effect Of Stratospheric Radiation On Seed Germination And Growth, B. N. Fong, K. V. Newhouse, M. J. Huss, E. Roberts, J. T. Kennon, H. Ali

Journal of the Arkansas Academy of Science

Three seed types: bean (Phaseolus vulgaris), corn (Zea mays) and radish (Raphanus sativus) were flown in a high altitude weather balloon into the mid-stratosphere to investigate the effects of high altitude radiation on germination success and seedling growth. After recovering and planting the seeds, the bean seeds showed lower germination success with exposure to high altitude radiation, and consequently stunted seedling growth. Cord and radish seeds experienced a statistically significant positive effect on germination success form radiation exposure compared to control seeds, but negative effect on seedling growth. Overall, the field experiments presented here support laboratory studies that show radiation …

Drought Resistance And Resilience Of Non-Native Vs. Native Grasses In The Northern Tallgrass Prairie, Wyatt Kirwan

Electronic Theses and Dissertations

Drought can have major impacts on rangeland productivity and remains highly unpredictable. Like many other rangelands in the US, the Tallgrass Prairie of eastern South Dakota contains native prairie where the plant composition includes mostly native species as well as pasture that has been converted to or invaded by cool-season introduced species. So how are these two plant communities impacted by drought? The specific objective of this study was to compare drought resistance and drought resilience of native prairie to introduced cool-season pasture (Smooth brome - Bromus inermis and Kentucky bluegrass - Poa pratensis). Our Hypothesis was that native prairie …

Discovery: The Student Journal Of Dale Bumpers College Of Agricultural, Food And Life Sciences - Volume 16 2015, Several Authors

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

No abstract provided.

Decadal Scale Responses Of Soil And Ecosystem Processes To Forest Restoration In Rocky Mountain Conifer Forests, Peter Ganzlin

Graduate Student Theses, Dissertations, & Professional Papers

Decades of fire suppression have left much of the forest in the intermountain western United States exceedingly dense, and forest restoration techniques – including thinning and prescribed fire – are increasingly being used in an attempt to mitigate the potentially disastrous effects of severe wildfire, to enhance tree growth and regeneration, and to stimulate soil nutrient cycling. While many of the short-term effects of forest restoration have been established, the long-term effects on soil biogeochemical and ecosystem processes are largely unknown. In this thesis I present two manuscripts documenting and synthesizing these long-term impacts. The first chapter focuses on the …

Foliar Fungicide Comparisons For Gray Leaf Spot Management And Lodging In Nebraska Field Corn, 2014, J. D. Harbour, T. A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The objective of the trial was to compare foliar fungicides with other fungicide programs for gray leaf spot (GLS) efficacy. Corn was grown under normal, irrigated agronomic practices at the South Central Ag Lab near Clay Center, NE. Soils were a silt loam with 6.7 pH and 1.8 % organic matter, and the previous crop was corn. Reduced tillage was performed to the field prior to planting. Corn (DKC 64-83 RIB, moderately susceptible to GLS) was planted at approximately 34,000 seed/A on 20 May. Eleven treatments were arranged in a randomized complete block design with six replications. . . . …

Corn Disease Update, Tamra A. Jackson-Ziems

Department of Plant Pathology: Faculty Publications

The harsh growing conditions during 2014 contributed to several disease problems in corn, in spite of the overall high yields across the state. The extended cold and wet conditions early in the season led to development of seedling diseases and crop stress. Then, in many parts of the state, repeated and unprecedented strong storms battered and wounded crops with multiple and widespread hail events, high winds, very heavy rain, and devastating tornadoes. Many fields were planted late or replanted, some more than once, further delaying the crop. Cool summer and fall conditions delayed maturity and led to early frost events …

What’S New In Plant Pathology, Tamra A. Jackson-Ziems, Loren Giesler, Robert M. Harveson, Stephen N. Wegulo, Kevin A. Korus, Tony O. Adesemoye

Department of Plant Pathology: Faculty Publications

Extension Plant Pathology Team Update

Changes to the Plant Disease Management Section of the 2015 Weed Guide

During the past year, several new products have become available for disease management. These products and additional products have been added to the Plant Disease Management Section of the 2015 Weed Guide. Products added to the Weed Guide have been summarized in Tables 1-3.

Table 1. Foliar Products

Table 2. Seed Treatment Products

Table 3. Seed Treatment Nematicides

Differentiating Chemical And Disease Symptoms In The Field, Kevin A. Korus, Loren J. Giesler, Robert M. Harveson, Tamra A. Jackson-Ziems, Lowell Sandell, Stephen Wegulo

Department of Plant Pathology: Faculty Publications

In years with conditions favorable for seedling disease and other disease there are typically concerns and inquiries about the cause(s) of symptoms in agronomic plants. Many of the questions focus on differentiating between plant injuries potentially caused by recent herbicide applications versus symptoms caused by plant pathogens. Chemical injury in row crops is caused by chemicals such as herbicides, fertilizers, fungicides, insecticides, growth regulators, and crop oils when they are applied individually, as a mixture, or together with adjuvants. If chemicals are applied incorrectly, plants may be damaged at any point during the growing season. Chemical injury can result from …

Large Dsdna Chloroviruses Encode Diverse Membrane Transport Proteins, Gerhard Thiel, Timo Greiner, David Dunigan, Anna Moroni

James Van Etten Publications

Many large DNA viruses that infect certain isolates of chlorella-like green algae (chloroviruses) are unusual because they often encode a diverse set of membrane transport proteins, including functional K+ channels and aquaglyceroporins as well as K+ transporters and calcium transporting ATPases. Some chloroviruses also encode putative ligand-gated-like channel proteins. No one protein is present in all of the chloroviruses that have been sequenced, but the K+ channel is the most common as only two chloroviruses have been isolated that lack this complete protein. This review describes the properties of these membrane-transporting proteins and suggests possible physiological functions and evolutionary histories …

Effect Of Waxy (Low Amylose) On Fungal Infection Of Sorghum Grain, Deanna L. Funnell-Harris, Scott E. Sattler, Patrick M. O'Neill, Kent M. Eskridge, Jeffrey F. Pedersen

Department of Plant Pathology: Faculty Publications

Loss of function mutations in waxy, encoding granule bound starch synthase (GBSS) that synthesizes amylose, results in starch granules containing mostly amylopectin. Low amylose grain with altered starch properties has increased usability for feed, food, and grain-based ethanol. In sorghum, two classes of waxy (wx) alleles had been characterized for absence or presence of GBSS: wx^a (GBSS^-) and wx^b (GBSS+, with reduced activity). Field-grown grain of wild-type; waxy, GBSS^-; and waxy, GBSS⁺ plant introduction accessions were screened for fungal infection. Overall, results showed that waxy grains were not more susceptible than …

Multi-Year Pathogen Survey Of Biofuel Switchgrass Breeding Plots Reveals High Prevalence Of Infections By Panicum Mosaic Virus And Its Satellite Virus, Catherine L. Stewart, Jesse D. Pyle, Charlene C. Jochum, Kenneth P. Vogel, Gary Y. Yuen, Karen-Beth G. Scholthof

Department of Plant Pathology: Faculty Publications

Switchgrass (Panicum virgatum) cultivars are currently under development as lignocellulosic feedstock. Here we present a survey of three established switchgrass experimental nurseries in Nebraska in which we identified Panicum mosaic virus (PMV) as the most prevalent virus. In 2012, 72% of 139 symptomatic plants tested positive for PMV. Of the PMV-positive samples, 19% were coinfected with its satellite virus (SPMV). Less than 14% of all sampled plants in 2012 were positive for four additional viruses known to infect switchgrass. In 2013, randomized sampling of switchgrass individuals from the same 2012 breeding plots revealed that infection by PMV or PMV+SPMV …

In Vitro Transcripts Of Wild-Type And Fluorescent Protein-Tagged Triticum Mosaic Virus (Family Potyviridae) Are Biologically Active In Wheat, Satyanarayana Tatineni, Anthony J. Mcmechan, Melissa Bartels, Gary L. Hein, Robert A. Graybosch

Department of Plant Pathology: Faculty Publications

Triticum mosaic virus (TriMV) (genus Poacevirus, family Potyviridae) is a recently described eriophyid mite-transmitted wheat virus. In vitro RNA transcripts generated from full-length cDNA clones of TriMV proved infectious on wheat. Wheat seedlings inoculated with in vitro transcripts elicited mosaic and mottling symptoms similar to the wildtype virus, and the progeny virus was efficiently transmitted by wheat curl mites, indicating that the cloned virus retained pathogenicity, movement, and wheat curl mite transmission characteristics. A series of TriMV-based expression vectors was constructed by engineering a green fluorescent protein (GFP) or red fluorescent protein (RFP) open reading frame with homologous …

Fine-Scale Genetic Structure Of Monilinia Fructicola During Brown Rot Epidemics Within Individual Peach Tree Canopies, Sydney E. Everhart, H. Scherm

Department of Plant Pathology: Faculty Publications

The purpose of this study was to determine the fine-scale genetic structure of populations of the brown rot pathogen Monilinia fructicola within individual peach tree canopies to better understand within-tree plant pathogen diversity and to complement previous work on spatiotemporal development of brown rot disease at the canopy level. Across 3 years in a total of six trees, we monitored disease development, collected isolates from every M. fructicola symptom during the course of the season, and created high-resolution three-dimensional maps of all symptom and isolate locations within individual canopies using an electromagnetic digitizer. Each canopy population (65 to 173 isolates …

Recommendations Of Generic Names In Diaporthales Competing For Protection Or Use, Amy Y. Rossman, Gerard C. Adams, Paul F. Cannon, Lisa A. Castlebury, Pedro W. Crous, Marieka Gryzenhout, Walter M. Jaklitsch, Luis C. Mejia, Dmitar Stoykov, Dhanushka Udayanga, Hermann Voglmayr, Donald M. Walker

Department of Plant Pathology: Faculty Publications

In advancing to one name for fungi, this paper treats generic names competing for use in the order Diaporthales (Ascomycota, Sordariomycetes) and makes a recommendation for the use or protection of one generic name among synonymous names that may be either sexually or asexually typified. A table is presented that summarizes these recommendations. Among the genera most commonly encountered in this order, Cytospora is recommended over Valsa and Diaporthe over Phomopsis. New combinations are introduced for the oldest epithet of important species in the recommended genus. These include Amphiporthe tiliae, Coryneum lanciforme, Cytospora brevispora, C. ceratosperma, C. …

Species Associated With Cytospora Canker On Populus Tremuloides, Jeff B. Kepley, F. Brent Reeves, William R. Jacobi, Gerard C. Adams

Department of Plant Pathology: Faculty Publications

A new species that is often associated with Cytospora chrysosperma was found commonly on stems of Populus tremuloides in Colorado. This fungus is illustrated and described as Cytospora notastroma sp. nov., and morphological and molecular data demonstrate that the new species is distinct from C. chrysosperma, C. nivea, C. translucens, and other species found on Populus. Diagnostic features are superficially visible, darkly pigmented conceptacles circumscribing the ascostromata and conidiomata and surrounding the white to grayish-white discs; some isolates produce a Phialocephala-like synanamorph in vitro in addition to the Cytospora anamorph.

School Gardens: Cultivating A Child’S Nutritional Habits, Environmental Knowledge, And Sustainability Practices, Jeffrey Meltzer

Honors Theses

School gardens have existed since the late nineteenth century and today are becoming increasingly popular in many parts of the world, including where I studied in Maine and Australia (AUS). Multiple organizations support school gardens in Maine, including the Maine School Garden Network, which has over 125 registered school gardens. In AUS, the Stephanie Alexander Kitchen Garden Foundation primarily supports the school garden movement and has over 800 registered school gardens. While many researchers have studied school gardens, few have compared two countries, focused on environmental sustainability, or investigated Maine in particular. This thesis combines information from literature reviews, and …

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 …

Little Things Reveal The Big Picture, W. John Hayden

Biology Faculty Publications

As enthusiasts who enjoy native plants in natural habitats, we tend to focus on gross morphology— aspects of plant form that can be readily observed with the naked eye or with a hand lens. And there is plenty to see at the gross level. The Flora of Virginia contains 1,269 pages of keys and descriptions devoted to gross morphology of the commonwealth’s botanical treasures. Morphological diversity, however, does not stop at the magnifi cation limit of a hand lens. Light and electron microscopes open up whole new worlds of intricate structure for appreciation and study. And tiny structural details can …

A Novel Mechanism To Explain Success Of Invasive Herbaceous Species At The Expense Of Natives In Eastern Hardwood Forests, Frank S. Gilliam

Biological Sciences Faculty Research

Among the more intriguing topics in general ecology courses are the symbiotic relationships (the ‘-isms’ as I sometimes present them – mutualism, commensalism, and parasitism). Of these, mutualism is typically the most appealing to students. The scenario that different species can not only co-exist, but can also provide essential resources/services for one another, resonates well with all but the least interested in the course. Ultimately, however, there is also the palpable degree of dismay when they discover that these relationships arise from mutual exploitation, rather than from some benign force of nature. A flip-side of this, in many ways a …

Classifying And Mapping Native Grasslands Of South Dakota's Northern Prairie Coteau And Characterizing Habitat For Dakota Skipper Conservation, Diane M. Narem

Electronic Theses and Dissertations

Native tallgrass prairie is becoming increasingly rare due to conversion and degradation, putting pressure on endemic prairie species such as the federally threatened Dakota skipper butterfly (Hesperia dacotae). To develop a conservation plan for the butterfly in South Dakota, accurate vegetation classification, mapping, and characterization are critical. The objectives of this study were to 1) rank prairie condition, 2) classify and map upland prairie, 3) characterize and compare vegetation at Dakota skipper inhabited and formerly inhabited sites, and 4) identify potential Dakota skipper habitat within a 225 mi2 (58,275 hectares) study area of the SD Prairie Coteau. Condition metrics were …

Plant Functional Traits Of Dominant Native And Invasive Species In Mediterranean-Climate Ecosystems, Jennifer L. Funk, Rachel J. Standish, William D. Stock, Fernando Valladares

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The idea that dominant invasive plant species outperform neighboring native species through higher rates of carbon assimilation and growth is supported by several analyses of global datasets. However, theory suggests that native and invasive species occurring in low-resource environments will be functionally similar, as environmental factors restrict the range of observed physiological and morphological trait values. We measured resource-use traits in native and invasive plant species across eight diverse vegetation communities distributed throughout the five Mediterranean-climate regions, which are drought-prone and increasingly threatened by human activities including the introduction of exotic species. Traits differed strongly across the five regions. In …

Quaking Aspen At The Residential-Wildland Interface: Elk Herbivory Hinders Forest Conservation., Paul C. Rogers, Allison Jones, James Catlin, James Shuler, Arthur Morris, Michael R. Kuhns

Aspen Bibliography

T: Quaking aspen (Populus tremuloides) forests are experiencing numerous impediments across North America. In the West, recent drought, fire suppression, insects, diseases, climate trends, inappropriate management, and ungulate herbivory are impacting these high biodiversity forests. Additionally, ecological tension zones are sometimes created at residential-wildland interfaces with divergent management directives. For example, private conservation reserves bordering public land may be degraded from browsing where game species find refuge from hunting and plentiful forage. We examined putative herbivore impacts to nearly pure aspen forests at Wolf Creek Ranch (WCR), a sparsely developed residential landscape in northern Utah. Forty-three one-hectare monitoring …

Altered Fire Regimes And The Persistence Of Quaking Aspen In The Rocky Mountains: A Literature Review, Aaron Rosenblum

Aspen Bibliography

The persistence of quaking aspen (Populus tremuloides Michx.) is of significant importance to land managers in the Rocky Mountain region. Fire suppression in the past century has been implicated as a mechanism influencing aspen population dynamics, as aspen are generally considered an early seral disturbance adapted species. The heterogeneity of aspen community assemblages and fire regimes makes it difficult to discern what the result of fire suppression has been at large spatial and temporal scales. Decision makers should investigate the questions at hand at the stand level in their study location to best determine the mechanisms at play, as well …

Long-Term Vegetation Change In Utah's Henry Mountains: A Study In Repeat Photography, Charles E. Kay

Aspen Bibliography

An extensive search was conducted of archival and other sources to locate as many historical photographs as possible for the Henry Mountains in south-central Utah. Those images were then taken into the field, the original camera stations relocated, and modern pictures made of the historical scenes to evaluate long-term vegetation change and land management activities. In all, 626 repeat photo sets were compiled—608 by the author and 18 by Earl Hindley. This book includes 126 photo sets that were representative of the areas studied.

Regeneration Dynamics Of White Spruce, Trembling Aspen, And Balsam Poplar In Response To Disturbance, Climatic, And Edaphic Factors In The Cold, Dry Boreal Forests Of The Southwest Yukon, Canada, Shyam K. Paudel, Craig R. Nitschke, Suzanne W. Simard, John L. Innes

Aspen Bibliography

The southwestern region of the Yukon Territory of Canada has experienced an unprecedented spruce bark beetle outbreak (Dendroctonus rufipennis) and an increase in the frequency of forest fires that extend beyond historical trends and that have caused significant impacts on forest structure and composition. A Strategic Forest Management Plan (SFMP) for the Champagne and Aishihik Traditional Territory located in the southwest Yukon was implemented in 2004 in response to the spruce bark beetle (D. rufipennis) infestation and increased fire risk. The plan has recommended salvage harvesting of beetle-killed stands as a strategy to facilitate the development …

Draft Genome Sequence Of Cercospora Arachidicola, Causal Agent Of Early Leaf Spot In Peanuts, Valerie A. Orner, Emily G. Cantowine, Xinye Monica Wang, Amr Abouelleil, James Bochicchio, Chad Nusbaum, Albert C. Culbreath, Zaid Abdo, Renee S. Arias

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Cercospora arachidicola, causal agent of early leaf spot, is an economically important peanut pathogen. Lack of genetic information about this fungus prevents understanding the role that potentially diverse genotypes may have in peanut breeding programs. Here, we report for the first time a draft genome sequence of C. arachidicola.

Transgenic Wheat Expressing A Barley Udp-Glucosyltransferase Detoxifies Deoxynivalenol And Provides High Levels Of Resistance To Fusarium Graminearum, Xi Li, Sanghyun Shin, Shane Heinen, Ruth Dill-Macky, Franz Berthiller, Natalya Nersesian, Thomas Clemente, Susan Mccormick, Gary J. Muehbauer

Department of Agronomy and Horticulture: Faculty Publications

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is a devastating disease of wheat that results in economic losses worldwide. During infection, F. graminearum produces trichothecene mycotoxins, including deoxynivalenol (DON), that increase fungal virulence and reduce grain quality. Transgenic wheat expressing a barley UDP-glucosyltransferase (HvUGT13248) were developed and evaluated for FHB resistance, DON accumulation, and the ability to metabolize DON to the less toxic DON-3-O-glucoside (D3G). Pointinoculation tests in the greenhouse showed that transgenic wheat carrying HvUGT13248 exhibited significantly higher resistance to disease spread in the spike (type II resistance) compared with nontransformed controls. Two transgenic …

A New Diploid Species Of Pilosella (Asteraceae) From Turkey, Vladimir Vladimirov, Kami̇l Çoşkunçelebi̇, Kit Tan

Turkish Journal of Botany

Pilosella ilgazensis Vladimirov, Coşkunçelebi & Kit Tan, a new diploid (2n = 2x = 18) species from Ilgaz Mountain National Park, North Anatolia, Turkey, is described and illustrated. It grows in subalpine grassland and open Juniperus sibirica Burgsd. communities. Pilosella ilgazensis is morphologically intermediate between P. alpicola s.l., from the high mountains of Central and Southeast Europe, and the Euro-Asiatic Pilosella echioides s.l. The relationship of the species with other similar taxa is discussed. The name Hieracium leontocephalum Halácsy, from a morphologically similar taxon from the Balkan Peninsula, is lectotypified, and a new generic combination, Pilosella leontocephala (Halácsy) Vladimirov, Coşkunçelebi …

Pollen Morphology Of The Genus Alchemilla L. (Rosaceae) In Iran, Marzieh Beygom Faghir, Farideh Attar, Robabeh Shahi Shavvon, Atefeh Mehrmanesh

Turkish Journal of Botany

This paper reports the morphological characters of 18 Iranian species of the genus Alchemilla using light and scanning electron microscopy. The pollen grains are monad, radially symmetrical, isopolar, or subisopolar; small to medium in size; tri- and tetracolporate; rectangular to cylindrical (from equatorial view) and triangular to circular (from polar view) in outline; and prolate-spheroidal to subprolate and prolate in shape. The exine ornamentation is psilate and microechinate. Based on the exine sculpturing and microechinate distribution pattern, three main types, four subtypes, and two categories of pollen grains were recognized. We used cluster analysis and principal component analysis to determine …

Seed Micromorphology In Dactylorhiza Necker Ex Nevski (Orchidaceae) And Allied Genera, Roberto Gamarra, Pablo Galan, Henrik Aerenlund Pedersen, Emma Ortunez, Ernesto Sanz

Turkish Journal of Botany

Seeds of 21 taxa of the genera Dactylorhiza (incl. Coeloglossum), Gymnadenia (incl. Nigritella) and Pseudorchis were examined by light microscope and SEM. Qualitative and quantitative characters were analyzed. In Dactylorhiza, the seeds are fusiform, but some populations of D. viridis show clavate seeds. According to the ornamentation of the periclinal walls, 3 types of seeds are recognized in this genus. The considerable variation in the seed coat ornamentation pattern in the taxa belonging to majalis, maculata, and praetermissa groups of the genus Dactylorhiza is congruent with the genetic processes that occurred during the history of this genus. Gymnadenia shows clavate …