Agriculture Commons^™

Parallel Altitudinal Clines Reveal Trends In Adaptive Evolution Of Genome Size In Zea Mays, Paul Bilinski, Patrice S. Albert, Jeremy J. Berg, James A. Birchler, Mark N. Grote, Anne Lorant, Juvenal Quezada, Kelly Swarts, Jinliang Yang, Jeffrey Ross-Ibarra

Department of Agronomy and Horticulture: Faculty Publications

While the vast majority of genome size variation in plants is due to differences in repetitive sequence, we know little about how selection acts on repeat content in natural populations. Here we investigate parallel changes in intraspecific genome size and repeat content of domesticated maize (Zea mays) landraces and their wild relative teosinte across altitudinal gradients in Mesoamerica and South America. We combine genotyping, low coverage whole-genome sequence data, and flow cytometry to test for evidence of selection on genome size and individual repeat abundance. We find that population structure alone cannot explain the observed variation, implying that …

Genomic Prediction Accuracy For Switchgrass Traits Related To Bioenergy Within Differentiated Populations, Jason D. Fiedler, Christina Lanzatella, Serge J. Edme, Nathan A. Palmer, Gautam Sarath, Rob Mitchell, Christian M. Tobias

Department of Agronomy and Horticulture: Faculty Publications

Background: Switchgrass breeders need to improve the rates of genetic gain in many bioenergy-related traits in order to create improved cultivars that are higher yielding and have optimal biomass composition. One way to achieve this is through genomic selection. However, the heritability of traits needs to be determined as well as the accuracy of prediction in order to determine if efficient selection is possible.

Results: Using five distinct switchgrass populations comprised of three lowland, one upland and one hybrid accession, the accuracy of genomic predictions under different cross-validation strategies and prediction methods was investigated. Individual genotypes were collected using GBS …

Method For The Production Of High Saturated, Low Polyunsaturated Soybean Oil, Thomas E. Clemente, Hyunwoo Park, Edgar B. Cahoon, Hanh Nguyen

Department of Agronomy and Horticulture: Faculty Publications

Methods of genetically modifying soybean plants to alter the fatty acid properties of the oil are described.

Establishing Growing Degree Day Estimates To Predict Critical Growth Stages In Soft Red Winter Wheat, Ethan J. Snyder

Theses and Dissertations--Plant and Soil Sciences

Predicting developmental growth stages in soft red winter wheat (Triticum aestivum L.) (SRWW) could improve agronomic management in Kentucky. However, predicting SRWW development is complex due to vernalization requirement and photoperiod sensitivity differences of cultivars. The objectives of this study are to (1) determine ability of Kompetitive Allele Specific PCR (KASP) genotyping to predict phenotype; (2) determine the relative vernalization requirement (RVR) of 50 SRWW cultivars in a greenhouse (GH) assay; and (3) measure growing degree-days (GDD) required by cultivars to reach eight growth stages in a field assay. Fifty SRWW cultivars were characterized with 14 KASP markers for …

Bacterial Inoculants, Endophytic Bacteria And Their Influence On Nicotiana Physiology, Development And Microbiome, Andrea Marisa Sanchez Barrios

Theses and Dissertations--Plant and Soil Sciences

Soil and root microbial communities have been studied for decades, and the incorporation of high-throughput techniques and analysis has allowed the identification of endophytic/non-culturable organisms. This has helped characterize and establish the core microbiome of many model plant species which include underground and aboveground organs. Unfortunately, the information obtained from some of these model plants is not always transferable to other agronomic species. In this project, we decided to study the microbiome of the Nicotiana genus because of its importance in plant physiological and plant-microbe interactions studies. The data obtained was used as baseline information that allowed us to better …

Chemical Topping Burley Tobacco, Mitchell D. Richmond

Theses and Dissertations--Plant and Soil Sciences

The act of topping tobacco (Nicotiana tabacum L.) involves the removal of the terminal bud or inflorescence of the tobacco plant. This practice ordinarily is accomplished by manually removing the top of each tobacco plant in an entire field which is labor intensive and costly. Chemical topping utilizes sucker control products to inhibit the terminal bud and axillary bud growth without manually removing the top of the tobacco plant. There were several research objectives in order to determine the utility of a chemical topping system: 1) determine if burley tobacco could be chemically topped with currently registered suckercide products …

Can Increasing Grass-Fungal Endophyte Symbiotic Diversity Enhance Grassland Ecosystem Functioning?, Mahtaab Bagherzadeh

Theses and Dissertations--Plant and Soil Sciences

The relationship between biodiversity and ecosystem functioning is important in maintaining agroecosystem sustainability. Plant-microbe symbioses, such as exists between the grass tall fescue (Schedonorus arundinaceum) and the asexual fungal endophyte Epichloë coenophiala, can be utilized to enhance agroecosystem functions, such as herbivore resistance. “Novel” E. coenophiala strains that vary in the production of mammal- and insect-toxic compounds have been identified, inserted into tall fescue cultivars, and are planted in pastures globally. Novel fungal endophyte-tall fescue associations may have divergent ecosystem function effects. This study assessed effects of different fescue-endophyte symbiotic combinations on pasture ecosystem function, including aboveground …

Engineering Zinc Oxide Nanoparticles To Be Used As Nanofertilizers, Zeinah Elhaj Baddar

Theses and Dissertations--Plant and Soil Sciences

Zinc deficient soils, or soils with low Zn bioavailability, are widespread, which exacerbates Zn deficiency in human as crops grown on these soils have low Zn content. Often crop yields are also compromised. Fertilizers based on soluble Zn salts often have limited efficacy in such soils. In this research, we evaluate the performance of polymer coated and bare ZnO nanoparticles (NPs) in an attempt to overcome limitations of soluble Zn salts in alkaline soils. We first synthesized 20-30 nm bare ZnO NPs with different surface chemistries to impart colloidal stability to the particles. Bare ZnO were treated in phosphate solution …

Characterizing Nitrogen Loss And Greenhouse Gas Flux Across An Intensification Gradient In Diversified Vegetable Systems, Debendra Shrestha

Theses and Dissertations--Plant and Soil Sciences

The area of vegetable production is growing rapidly world-wide, as are efforts to increase production on existing lands in these labor- and input-intensive systems. Yet information on nutrient losses, greenhouse gas emissions, and input efficiency is lacking. Sustainable intensification of these systems requires knowing how to optimize nutrient and water inputs to improve yields while minimizing negative environmental consequences. This work characterizes soil nitrogen (N) dynamics, nitrate (NO₃¯) leaching, greenhouse gas emissions, and crop yield in five diversified vegetable systems spanning a gradient of intensification that is characterized by inputs, tillage and rotational fallow periods. The study systems …

A Mycobacterium Avium Subsp. Paratuberculosis Rela Deletion Mutant And A 35 Kda Major Membrane Protein Elicit Development Of Cytotoxic T Lymphocytes With Ability To Kill Intracellular Bacteria, Gaber S. Abdellrazeq, Mahmoud M. Elnaggar, J. P. Bannantine, Kun Park, Cleverson D. Souza, Brian Backer, Victoria Hulubei, Lindsay M. Fry, Samy A. Khaliel, Helmy A. Torky, David A. Schneider, William C. Davis

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

Efforts to develop live attenuated vaccines against Mycobacterium avium subspecies paratuberculosis (Map), using indirect methods to screen Map deletion mutants for potential efficacy, have not been successful. A reduction in the capacity to survive in macrophages has not predicted the ability of mutants to survive in vivo. Previous studies for screening of three deletion mutants in cattle and goats revealed one mutant, with a deletion in relA (ΔMap/relA), could not establish a persistent infection. Further studies, using antigen presenting cells (APC), blood dendritic cells and monocyte derived DC, pulsed with ΔMap/relA or a 35 kDa Map membrane protein (MMP) revealed …

Framing Contemporary U.S. Wild Horse And Burro Management Processes In A Dynamic Ecological, Sociological, And Political Environment, J. Derek Scasta, Jacob D. Hennig, Jeffrey L. Beck

Human–Wildlife Interactions

The Wild Free-Roaming Horses and Burros Act (WFRHBA) of 1971 established all “unbranded or unclaimed” equids on U.S. public lands as “living symbols of the historic and pioneer spirit of the West.” Today, >72,000 feral horses (Equus ferus caballus) and burros (E . asinus ; WHB) live on western U.S. public rangelands. The number of WHBs exceeds the Bureau of Land Management’s maximum Appropriate Management Level (AML) of 26,715 by a factor of approximately 2.7 and has nearly doubled from 2007–2015. The AML was set to balance WHB numbers with rangeland health and support other uses such as wildlife habitat …

Spatial Ecology Observations From Feral Horses Equipped With Global Positioning System Transmitters, Jacob D. Hennig, Jeffrey L. Beck, J. Derek Scasta

Human–Wildlife Interactions

Our understanding of the spatial ecology of feral horses (Equus ferus caballus ) and burros (E . asinus ) in the United States is limited. Robust location data are needed to better understand the permeability of Bureau of Land Management Herd Management Area boundaries, relative to feral horse movement patterns and home ranges. To increase our understanding of feral horse movement, in February to March 2017, we deployed global positioning system (GPS) collars on 14 females ≥5 years old that were captured in the Adobe Town Herd Management Area (ATHMA) of southcentral Wyoming, USA. Herein, we report initial results from …

The Three Creeks Allotment Consolidation: Changing Western Federal Grazing Paradigms, Taylor Payne

Human–Wildlife Interactions

The federal government owns approximately 47% of all land in the western United States. In the state of Utah, about 64% of the land base is managed by the federal Bureau of Land Management (BLM) and the U.S. Forest Service (USFS). The government has historically issued permits to owners of private lands to allow the owners to graze their livestock on public lands. The permits (allotments) are generally of 10-year duration and allow for an annual season of use. In some cases, continued and repeated historical annual grazing practices may not be ideal for permit holders and their communities nor …

Measuring The Influence Of Bedding On Soil Nitrogen Losses And Corn Crop Nitrogen Characteristics For Fall Applied Solid Beef Cattle Manure In Eastern South Dakota, Mukesh Mehata

Electronic Theses and Dissertations

Nitrogen (N) is a major component of chlorophyll which plays a key role in the photosynthesis process in crops. The N is one of the highest demanded nutrients by all plants for their growth and reproduction. Manure or inorganic fertilizer is often applied to fulfill the crops’ N demand. However, the applied N sources have the potential of N losses in different forms from the soil volume in many ways such as ammonia (NH₃) volatilization, aerial nitrous oxide (N₂O) loss, nitrate (NO₃ --N) leaching, and runoff and/or erosion. Soil fertility, crop yield, water quality, and …

Cc-Type Glutaredoxins Mediate Plant Response And Signaling Under Nitrate Starvation In Arabidopsis, Ji-Yul Jung, Ji Hoon Ahn, Daniel P. Schachtman

Department of Agronomy and Horticulture: Faculty Publications

Background: Nitrogen is an essential nutrient in plants. Despite the importance of nitrogen for plant growth and agricultural productivity, signal transduction pathways in response to nitrate starvation have not been fully elucidated in plants.

Results: Gene expression analysis and ectopic expression were used to discover that many CC-type glutaredoxins (ROXYs) are differentially expressed in response to nitrate deprivation. A gain-of-function approach showed that ROXYs may play a role in nutrient sensing through the regulation of chlorophyll content, root hair growth, and transcription of nitrate-related genes such as NRT2.1 under low or high nitrate conditions. Reactive oxygen species (ROS) …

Risks And Opportunities Of Gm Crops: Bt Maize Example, Andrea K. Carzoli, Siddique I. Aboobucker, Leah L. Sandall, Thomas T. Lubberstedt, Walter P. Suza

Department of Agronomy and Horticulture: Faculty Publications

The anticipated world population growth emphasizes a need to produce more food on less land. Cutting-edge technologies, including genetic engineering, can help to develop improved crop varieties and protect natural resources. In spite of the potential for genetically-modified (GM) crops to make crop production more efficient, they remain a polarizing issue due to safety concerns. This paper provides an overview of the risk assessment process. The safety of Bacillus thuringiensis (Bt) proteins is used as an example for how risk assessment is applied to GM crops. Risks associated with GM crops have proven to be low to non-existent. Developing countries …

Agri 115: Biotechnology – Food, Health And Environment, A Peer Review Of Teaching Project Benchmark Portfolio, Leah Sandall

UNL Faculty Course Portfolios

No abstract provided.

Aecn 141- Introduction To The Economics Of Agriculture, Timothy Meyer

UNL Faculty Course Portfolios

Course portfolio for AECN 141- Introduction to the Economics of Agriculture, University of Nebraska-Lincoln.

Zoning And Complementary Incentives To Protect Farmland: A Case For Missoula County, Kaitlin Mccafferty

Graduate Student Theses, Dissertations, & Professional Papers

Urban sprawl reflects an inefficient use of land that diminishes both rural landscapes and quality of life turning farms, ranches and open space into siloed suburban communities. This results in less walkable cities with more traffic and air pollution, among other negative consequences. Farmland constitutes a particularly important resource that often faces degradation or loss due to sprawl. Higher quality agricultural soils are particularly desirable for development because they are flat and well-drained. Farmland is also important for urban communities concerning food security, environmental health, and economic well being. As American cities continue to grow, farmland around urban areas has …

Arthropod Diets In Chihuahuan Desert Snakes, Victor Manuel Parga

Open Access Theses & Dissertations

Over the past century, studies in herpetology regarding snake diets have been commonly focused on those species that feed or specialize in vertebrate prey items. For those that feed primarily on invertebrates however, little work has been done in determining diet specializations and comparing diets within a community of species. This Thesis focuses on small species of snakes that feed primarily on arthropods in a Chihuahuan Desert community, and will investigate if these are diet generalists or specialists. To this end, stomach contents were examined from preserved specimens of the following species: Rena humilis and Rena dissecta (Leptotyphlopidae), Gyalopion canum …