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Full-Text Articles in Life Sciences

Canavalia And Dolichos Extracts For Sustainable Pest Biocontrol And Plant Nutrition Improvement In El Salvador, Carlos Martinez Oct 2019

Canavalia And Dolichos Extracts For Sustainable Pest Biocontrol And Plant Nutrition Improvement In El Salvador, Carlos Martinez

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Botanical repellents and pesticides are now being rediscovered as new tools for integrated pest management in order to reduce the use of toxic chemicals in crop production. Canavalia gladiata and Dolichos lablab are two Fabaceae very well adapted to farmlands of El Salvador, effective as living barriers and mostly as cover crops, however, they are not yet very well disseminated. This document describes the potential for using the liquid extracts and the dry flour of raw seeds of those plants for economic benefit and practical convenience for pest management in Salvadorian agriculture under field conditions. Seed extracts were useful when ...


Expression Of Multi-Domain Lytic Peptide Genes In Transgenic Plants For Disease Resistance, George Biliarski Aug 2019

Expression Of Multi-Domain Lytic Peptide Genes In Transgenic Plants For Disease Resistance, George Biliarski

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Four non-plant multi-domain lytic peptide genes coding for antimicrobial peptides were expressed in Nicotiana benthamiana plants and tested against three fungal pathogens: Sclerotinia sclerotiorum, Rhizoctonia solani, and Pythium sp. Detached-leaf bioassay was performed for the transgenic plants carrying multi-domain lytic peptide constructs and compared with transgenic and wild type control plants. Symptom area of each leaf was measured with high precision using the Compu-Eye software and processed by SAS statistical package. The transgenic lines ORF13 and RSL1 showed substantial resistance to Sclerotinia sclerotiorum infection producing significantly smaller lesion areas compared to control plants. However, these lines were not ...


Rust And Viral Mosaic Diseases In Biofuel Switchgrass, Anthony A. Muhle Aug 2019

Rust And Viral Mosaic Diseases In Biofuel Switchgrass, Anthony A. Muhle

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Switchgrass (Panicum virgatum L.) is a perennial warm-season monocot that is indigenous to locations in North America east of the Rocky Mountains, and is considered a model grass for biofuel feedstock production. As switchgrass production increases, diseases pose a potential threat to biomass production and ethanol extraction. The two predominant switchgrass diseases in Nebraska are rust caused by Puccinia spp. and a viral mosaic disease caused by Panicum mosaic virus (PMV) and its associated Satellite panicum mosaic virus (SPMV). In this thesis, one study determined how SPMV affects PMV infection and systemic spread in two populations of switchgrass at different ...


Investigating Parental Effects On End-Use Quality In Hard Winter Wheat (Triticum Aestivum L.) Hybrids, Anthony Delaney Aug 2019

Investigating Parental Effects On End-Use Quality In Hard Winter Wheat (Triticum Aestivum L.) Hybrids, Anthony Delaney

Theses, Dissertations, and Student Research in Agronomy and Horticulture

To optimize the performance and marketing of hybrid wheat, breeders need to understand the impact parents have on end-use quality. The goal of this study was to investigate the inheritance of end-use quality traits of hard winter wheat reciprocal hybrids produced by Easterly (2017). The 2016 analysis included 71 reciprocal hybrid combinations from 13 parents and the 2017 analysis included 79 reciprocal hybrid combinations from 14 parents. The reciprocals were composed of crosses between the top performing and bottom performing parents with respect to end-use quality as quantified by a Mixograph, a SDS sedimentation assay, and a SDS-SRC hybrid assay ...


An Integrated Genomics And Phenomics Approach To Study The Evolution Of C4 Photosynthesis, Daniel Santana De Carvalho Aug 2019

An Integrated Genomics And Phenomics Approach To Study The Evolution Of C4 Photosynthesis, Daniel Santana De Carvalho

Theses, Dissertations, and Student Research in Agronomy and Horticulture

The C4 photosynthetic pathway was first described over 50 years ago. Today, it is known that C4 evolved independently > 60 in plant lineages, which involves understanding not only the genetic, but also the metabolic features and differences involved in this process. Also, several adaptations are involved in the evolution of this type of photosynthesis, for example: changes in leaf anatomy and the evolution of kranz anatomy, physiology and metabolic pathways. In order to further investigate this pathway, different technologies and methods have been developed to unravel genes involved in C4 photosynthesis. With the advances in molecular biology and bioinformatics tools ...


Hormonal Signaling Induced In Soybean By Lysobacter Enzymogenes Strain C3, Jessica C. Walnut Aug 2019

Hormonal Signaling Induced In Soybean By Lysobacter Enzymogenes Strain C3, Jessica C. Walnut

Theses, Dissertations, and Student Research in Agronomy and Horticulture

The biological control bacterium Lysobacter enzymogenes strain C3 has been shown to suppress fungal diseases by producing a suite of lytic enzymes and antimicrobial secondary metabolites. Previous studies have found that C3, when applied to grass and cereal plants, also is capable of inducing local and systemic resistance against fungal pathogens. It is unknown, however, whether the bacterium has the ability to induce resistance in dicots and what signaling pathways are involved. This study assessed the ability of C3 to trigger local and systemic induced resistance responses in soybean (Glycine max ‘Williams82’) by analyzing relative expression of salicylic acid (SA ...


New Approaches To Use Genomics, Field Traits, And High-Throughput Phenotyping For Gene Discovery In Maize (Zea Mays), Zhikai Liang Aug 2019

New Approaches To Use Genomics, Field Traits, And High-Throughput Phenotyping For Gene Discovery In Maize (Zea Mays), Zhikai Liang

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Maize is one of major crop species over the world. With lots of genetic resources and genomic tools, maize also serves as a model species to understand genetic diversity, facilitate the development of trait extraction algorithms and map candidate functional genes. Since the first version of widely used B73 reference genome was released, independent research groups in the maize community propagated seeds themselves for further research purposes. However, unexpected or occasional contamination may happen during this process. The first study in this thesis used public RNA-seq data of B73 from 27 research groups across three countries for calling single nucleotide ...


Dual Biological Control: Characterization Of Fungi And Bacteria To Control Granary Weevil And Fungal Pathogens Of Stored Grain, Gülçin Ercan Aug 2019

Dual Biological Control: Characterization Of Fungi And Bacteria To Control Granary Weevil And Fungal Pathogens Of Stored Grain, Gülçin Ercan

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Cereals are main food sources for humans and animals. However, during storage, cereal grains can be infested by insects and fungi. One of the most important insect storage pests is Sitophilus granarius (L., Coleoptera: Curculionidae). Adults and larvae can cause serious grain losses. In addition to insect pests, fungal pathogens may also invade the grain and cause economic loss, including contamination with mycotoxins, which threaten mammal health by causing serious disease. The most common mycotoxigenic grain fungi are species that belong to the genera Fusarium, Aspergillus and Penicillium. Currently, the most commonly used management strategies for insect and fungal storage ...


Herbicide Drift Influence On Amaranthus Spp. Herbicide Resistance Evolution, Bruno Canella Vieira Jul 2019

Herbicide Drift Influence On Amaranthus Spp. Herbicide Resistance Evolution, Bruno Canella Vieira

Theses, Dissertations, and Student Research in Agronomy and Horticulture

The adverse consequences of herbicide drift towards sensitive crops have been extensively reported in the literature. However, no information is available on the consequences of herbicide drift onto weed species inhabiting boundaries of agricultural fields. Exposure to herbicide drift could be detrimental to long-term weed management as several weed species have evolved herbicide resistance after recurrent selection with low herbicide rates. Despite the herbicide drift exposure and its potential implications on resistance evolution and weed management, resistance prone weed species such as Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus) are often neglected and not properly managed in agricultural field ...


Biomethane Production From Distillery Wastewater, Zachary Christman Jun 2019

Biomethane Production From Distillery Wastewater, Zachary Christman

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Distillery wastewater treatment is a great ecological problem, for example, India produces 2.7 billion liters of alcohol that results in 40 billion liters of wastewater. However, this material can be seen as a resource since 11 million cubic meters of biogas at 60% methane could be produced in addition to cleaning the water. The distillery has two options of what to do with the biogas. The first is to use the biogas to fuel the distillery making the production plant more energy efficient and removing some of the need to buy natural gas. The other is to upgrade the ...


Introduction To Sorghum Paper Production, Zachary Christman May 2019

Introduction To Sorghum Paper Production, Zachary Christman

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Sorghum is a tall grass used for many commercial products such as fodder and syrup. The 10 to 15 feet stalk of the plant has lower lignin than wood and provides a fiber length of 2.31 mm in the outer covering and 1.38 mm for the leaf. Sorghum fiber makes a high quality, strong paper suitable for printing, packaging and paperboard.


Effect Of Soil-Applied Protoporphyrinogen Oxidase Inhibitor Herbicides On Soybean Seedling Disease, Nicholas J. Arneson May 2019

Effect Of Soil-Applied Protoporphyrinogen Oxidase Inhibitor Herbicides On Soybean Seedling Disease, Nicholas J. Arneson

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Seedling disease is one the most economically important diseases of soybean in the United States. It is commonly caused by Fusarium spp., Rhizoctonia solani, Pythium spp., and Phytophthora sojae, alone, or together as a disease complex. Fungicide seed treatments continue to provide the most consistent management of seedling diseases. Soil-applied protoporphyrinogen oxidase (PPO) inhibitor herbicides are used preemergence in soybean production to manage several broadleaf weeds. Applications of PPO-inhibitors can result in phytotoxic injury to soybean when environmental conditions are not favorable for soybean growth. These environmental conditions can favor seedling disease development as well. In this thesis, two studies ...


Use Of Annual Forage Mixtures In Crop/Livestock Production Systems In Nebraska, Nathan Paul Pflueger May 2019

Use Of Annual Forage Mixtures In Crop/Livestock Production Systems In Nebraska, Nathan Paul Pflueger

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Success of integrating annual forages into crop and livestock systems throughout Nebraska may be variable depending on field location, field/forage crop management, and precipitation. There are many different warm- and cool-season annual forage species available for integrating crop and livestock systems at different times of the year. Mixtures of cereal species, such as oats (Avena sativa)) and spring peas (Pisum sativum)), are often used to optimize forage quantity and forage quality. Our two-year, three location study across Nebraska’s precipitation gradient suggested that forage quantity and quality may vary by location due to different precipitation amounts received during the ...


Establishment Of Perennial Legumes With An Annual Warm-Season Grass As A Companion Crop, Martina N. La Vallie May 2019

Establishment Of Perennial Legumes With An Annual Warm-Season Grass As A Companion Crop, Martina N. La Vallie

Theses, Dissertations, and Student Research in Agronomy and Horticulture

The yields of perennial forage legumes are often hindered during the establishment year due to slow germination rates and weed competition. This study was conducted to determine if sorghum-sudangrass (Sorghum bicolor x S. bicolor var. sudanese) is a compatible annual companion crop for increased forage production, weed suppression, and legume establishment. In 2016, sorghum-sudangrass was paired with alfalfa (Medicago sativa L. ‘Ranger’), birdsfoot trefoil (Lotus corniculatus L.), Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMill. ex B.L. Rob. & Fernald], purple prairie clover (Dalea purpurea Vent.), red clover (Trifolium pratense L.), and roundhead lespedeza (Lespedeza capitata Michx.). We studied effects of a sorghum-sudangrass companion crop with a varying number of harvests (three vs. four harvests) collected per plot throughout the summer and compared yields to the yield of a weeded legume treatment, and a non-weeded legume treatment. In 2017, we studied effects of the application of four seeding rates for sorghum-sudangrass at 5 pure live seed per m2 (PLS/m2), 10 PLS/m2, 20 PLS/m2, and 40 PLS/m2 paired with only the alfalfa perennial legume and compared yields to the yield of an oat-alfalfa control treatment, a weeded alfalfa treatment, and a non-weeded alfalfa treatment. Total dry matter yields along with the yield of each legume, weeds, sorghum-sudangrass, and oats (second year only) were collected for each treatment. In both years, we found the addition of sorghum-sudangrass increased overall dry matter yield and significantly decreased weed abundance. The increase in total dry matter yield came at a cost to the legume yield; as treatments planted with sorghum-sudangrass or oats had lower legume/alfalfa yields than weeded legume/alfalfa treatments. These results suggest that sorghum-sudangrass is ...


Integrated Management Of Phytophthora Stem And Root Rot Of Soybean And The Effect Of Soil-Applied Herbicides On Seedling Disease Incidence, Vinicius Castelli Garnica May 2019

Integrated Management Of Phytophthora Stem And Root Rot Of Soybean And The Effect Of Soil-Applied Herbicides On Seedling Disease Incidence, Vinicius Castelli Garnica

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Soybean seedling diseases and Phytophthora stem and root rot (PSRR; caused by Phytophthora sojae) are two of the most economically important diseases in North Central U.S. Remarkable differences in disease incidence occur each year, which demonstrate that abiotic and biotic factors must interact for disease onset and development. During 2017 and 2018, field studies were conducted to (i) address the efficacy of seed treatment and genetic resistance for PSRR management on soybean population, canopy coverage (CC), and yield, and (ii) investigate potential interactions between pre-emergence (PRE) herbicides and the incidence of seedling diseases in alluvial soils in Nebraska.

Despite ...


Dna Barcoding Of Pratylenchus From Agroecosystems In The Northern Great Plains Of North America, Mehmet Ozbayrak May 2019

Dna Barcoding Of Pratylenchus From Agroecosystems In The Northern Great Plains Of North America, Mehmet Ozbayrak

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Pratylenchus species are among the most common plant parasitic nematodes in the Great Plains Region. The objectives of this study were to barcode Pratylenchus specimens for species identification in the Great Plains region using mitochondrial CO1 DNA barcode. In order to (1) determine species boundaries, (2) assess the host associations of barcoded Pratylenchus, (3) to determine the distribution patterns across the Great Plains Region and, (4) to evaluate the species status of P. scribneri and P. hexincisus by a multivariate morphological analysis of haplotype groups identified by DNA barcoding. Soil samples, primarily associated with eight major crops, were collected from ...


Genome-Wide Association Studies In Maize And Sorghum, Preston Hurst Apr 2019

Genome-Wide Association Studies In Maize And Sorghum, Preston Hurst

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Genome-wide association studies are used to identify genetic variants associated with a particular phenotype. GWAS has been used in a variety of taxa, from humans, to fish to plants . The present analysis is focused on two species important to the human species: maize and sorghum. A GWAS in maize was carried out on the modification of the Ga1-s allele. The Ga1 locus has long been studied as being involved in a unilateral crossing barrier . However, it has long been suspected that the locus is modified by background genetic factors . GWAS was used to observe candidates for this modification. A series ...


Improving The Distribution And Use Of Biogas By Conversion To Methanol, Zachary Christman Mar 2019

Improving The Distribution And Use Of Biogas By Conversion To Methanol, Zachary Christman

Theses, Dissertations, and Student Research in Agronomy and Horticulture

In this technology review, the process of turning an average biogas into methanol will be presented. The purpose is to find a better method of transporting the energy contained within biogas so that it may be used in industry as a value added product. The first step is removal of hydrogen sulfide, a corrosive chemical that can breakdown mechanical parts. The second step is carbon capture and conversion of the biogas into hydrogen. The final step is the hydrogenation of carbon dioxide into methanol using a copper catalyst and an alcohol co-catalyst.


Evaluation Of Stabilized Fertilizer And Crop Canopy Sensors As Next-Generation Nitrogen Management Technologies In Irrigated Corn, Leonardo Mendes Bastos Feb 2019

Evaluation Of Stabilized Fertilizer And Crop Canopy Sensors As Next-Generation Nitrogen Management Technologies In Irrigated Corn, Leonardo Mendes Bastos

Theses, Dissertations, and Student Research in Agronomy and Horticulture

Nitrogen (N) is often the most limiting nutrient to corn. Once applied to the field, N can be lost through different pathways, which contributes to low N use efficiency (NUE) by plants. Increases in NUE and decreases in N losses can be potentially achieved by using management options that allow a better synchrony between N supply and demand, such as stabilized fertilizers, and spatially-variable sensor-derived in-season N application. Three studies were conducted in order to assess the effects of different stabilized fertilizers and crop canopy sensors on irrigated corn yield. The first study evaluated the effect of urease inhibitor on ...