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Effects Of Nematicidal Seed Treatments On The Biology Of The Soybean Cyst Nematode, Heterodera Glycines, Jared Paul Jensen Jan 2017

Effects Of Nematicidal Seed Treatments On The Biology Of The Soybean Cyst Nematode, Heterodera Glycines, Jared Paul Jensen

Graduate Theses and Dissertations

Nematicidal seed treatments are a welcomed new tool to manage the soybean cyst nematode, Heterodera glycines, in soybean production. Results of field-based research on the effects of nematicidal seed treatments have been inconsistent and do not indicate how or when a seed treatment affects the nematode. This dissertation describes 1) the development of new methods to study H. glycines biology and 2) the use of new and traditional methods to study the effects of Avicta® (abamectin) and Clariva® (Pasteuria nishizawae) seed treatments on the biology of H. glycines.

Two new methods were developed to study the behavior of ...


Effects Of Cover Crops And Tillage In A Muskmelon Production System, John Hampton Krzton-Presson Jan 2017

Effects Of Cover Crops And Tillage In A Muskmelon Production System, John Hampton Krzton-Presson

Graduate Theses and Dissertations

Most muskmelon (Cucumis melo L.) production in the upper Midwest relies on intensive tillage and plasticulture. An alternative system starts with the use of a roller-crimper to terminate winter cover crops, thus forming a thick organic mulch. Then, all tillage performed is restricted to a narrow strip in which muskmelons are transplanted. Cover crops and strip-tillage can increase soil health, suppress weeds, and improve net profitability. Muskmelons are an important crop for vegetable growers and are among the top consumed produce items in the U.S. Foodborne illness outbreaks of Salmonella and Listeria monocytogenes associated with muskmelon consumption have resulted ...


How Does Inclusion Of Weather Forecasting Impact In-Season Crop Model Predictions?, Kaitlin Togliatti Jan 2017

How Does Inclusion Of Weather Forecasting Impact In-Season Crop Model Predictions?, Kaitlin Togliatti

Graduate Theses and Dissertations

Accurately forecasting crop yield in advance of harvest could greatly benefit decision makers. However, few evaluations have been conducted to determine the effectiveness of including weather forecasts, as opposed to using historical/climatology data, into crop models. We tested a combination of short-term weather forecasts from the Weather Research and Forecasting Model (WRF) to predict in season weather variables, such as, maximum and minimum temperature, precipitation, and radiation at four different forecast lengths (14 days, 7 days, 3 days, and 0 days). This forecasted weather data along with the current and historic (previous 35 years) data were combined to drive ...


A Comparative Survey And Investigation Into The Functional Role Of Root Anatomy In The Poaceae, Monica Cox Jan 2017

A Comparative Survey And Investigation Into The Functional Role Of Root Anatomy In The Poaceae, Monica Cox

Graduate Theses and Dissertations

Given the diversity of grasses and the habitats they occupy, it was predicted that a broad survey of root anatomy would reveal a range of variation. A comparative survey of trans-sectional root anatomy of the mature stele in the Poaceae, sampling 76 species representing all 12 subfamilies from herbarium and fresh-fixed specimens has been undertaken. The species are a subset of the 157 species of grasses for which plastomes (plastid genome), leaf shape data, and leaf anatomical data are available. Quantitative and qualitative characters including endodermal cell radial thickness and inner-tangential wall thickness, stele area, and metaxylem vessel diameters were ...


A Study Of Cell Wall Integrity Control In Transgenic Plants Expressing Polysaccharide-Modifying Enzymes, Nathan T. Reem Jan 2017

A Study Of Cell Wall Integrity Control In Transgenic Plants Expressing Polysaccharide-Modifying Enzymes, Nathan T. Reem

Graduate Theses and Dissertations

Plants have developed specialized mechanisms for dealing with different stresses. For example, biotic stresses are sensed extracellularly, through Cell Wall Integrity (CWI) control. CWI control is a complex system that works via a set of receptors and signaling networks that allow cells to sense pathogens and initiate defense responses. This dissertation aims to uncover cell wall-mediated mechanisms and underlying signaling of CWI using post-synthetic modification of plant cell walls by microbial cell wall degrading enzymes (CWDEs).

We first compared CWI in Arabidopsis thaliana and Brachypodium distachyon plants expressing a Ferulic Acid Esterase (AnFAE). Both species exhibited reduced cell wall recalcitrance ...


Perennial Groundcovers For Maize-Based Bioenergy Production Systems, Cynthia Anna Bartel Jan 2017

Perennial Groundcovers For Maize-Based Bioenergy Production Systems, Cynthia Anna Bartel

Graduate Theses and Dissertations

Natural resources degradation in conventional cropping systems and renewable fuels agendas underscore the importance of developing alternative cropping systems which can both (1) conserve natural resources and (2) meet global demands for food, feed, fiber, and fuel. The integration of perennial groundcover (PGC) into annual grain cropping systems is uniquely positioned to achieve production goals and alleviate the degradation of natural resources. We established kentucky bluegrass (KB) (Poa pratensis L.) or creeping red fescue (CF) (Festuca rubra L.) as PGC concurrently with either three unique maize hybrids or soybean, and field studies were conducted with the objective of (i) establishing ...


Identification Of Spectral Disease Signatures And Resistant Qtl For Charcoal Rot Infection In Soybean, Sarah Jones Jan 2017

Identification Of Spectral Disease Signatures And Resistant Qtl For Charcoal Rot Infection In Soybean, Sarah Jones

Graduate Theses and Dissertations

Disease phenotyping is an important process for both production field scouting and disease rating in soybean [Glycine max (L.) Merr.] breeding programs because yield is affected by many pathogens including charcoal rot, Macrophomina phaseolina. Charcoal rot has limited chemical control options and affects over 500 species worldwide making crop rotation a difficult management strategy as well. Due to these management challenges, breeding for disease resistance is a valuable strategy, however traditional disease phenotyping relies on human visual ratings which are prone to human error and have scalability issues when moving to large production schemes or modern breeding programs. Furthermore, there ...


Determining Aroma Differences Among Basil, Parsley, And Dill Grown Under Varied Supplemental Light Wavelengths Using Consumer Sensory And Flash Gas Chromatograph-Electronic Nose Analyses, Anne Kalyn Seely Jan 2017

Determining Aroma Differences Among Basil, Parsley, And Dill Grown Under Varied Supplemental Light Wavelengths Using Consumer Sensory And Flash Gas Chromatograph-Electronic Nose Analyses, Anne Kalyn Seely

Graduate Theses and Dissertations

Greenhouse herb producers may use artificial lighting to supplement the natural light available to their crops. High-pressure sodium (HPS) lights are the most common supplemental lighting systems employed in such operations, but light-emitting diode (LED) lighting is increasing in popularity because of its energy efficiency, customizability, and environmental friendliness. LED lights can be customized to emit specific proportions of light wavelengths, but many herb producers do not know how these “light recipes” affect their crops, specifically their crops’ aroma. This research utilized consumer sensory difference panels and flash gas chromatograph-electronic nose (GC-EN) analysis to evaluate the aroma of fresh basil ...


Engineering Analytics Through Explainable Deep Learning, Sambuddha Ghosal Jan 2017

Engineering Analytics Through Explainable Deep Learning, Sambuddha Ghosal

Graduate Theses and Dissertations

Pattern recognition has its origins in engineering while machine learning developed from computer science. Today, artificial intelligence (AI) is a booming field with many practical applications and active research topics that deals with both pattern recognition and machine learning. We now use softwares and applications to automate routine labor, understand speech (using Natural Language Processing) or images (extracting hierarchical features and patterns for object detection and pattern recognition), make diagnoses in medicine, even intricate surgical procedures and support basic scientific research.

This thesis deals with exploring the application of a specific branch of AI, or a specific tool, Deep Learning ...


Soybean-Pythium Pathosystem: Search For Host Resistance And Interaction With Fusarium Species, Elizabeth Rose Lerch Jan 2017

Soybean-Pythium Pathosystem: Search For Host Resistance And Interaction With Fusarium Species, Elizabeth Rose Lerch

Graduate Theses and Dissertations

Seedling disease of soybean is an economically important disease that reduces crop stands and may reduce yield. Symptoms of seedling disease include pre- and post-emergence damping-off and root rot. Many species of Pythium and Fusarium cause seedling disease and are frequently recovered together from diseased soybean seedlings. Host resistance as a strategy to manage multiple pathogens has only briefly been explored in soybean and the interaction between these pathogens is unclear. To better understand the soybean-Pythium pathosystem, lab and growth chamber assays were conducted to accomplish the following objectives, 1) identify with resistance to seed and root rot caused by ...


Utilization Of Polyanhydride Nanoparticle Encapsulated Fungicide Seed Treatments Against Seedborne And Soilborne Fusarium Graminearum On Maize, Lauren Alicia Washington Jan 2017

Utilization Of Polyanhydride Nanoparticle Encapsulated Fungicide Seed Treatments Against Seedborne And Soilborne Fusarium Graminearum On Maize, Lauren Alicia Washington

Graduate Theses and Dissertations

Fusarium graminearum is a soilborne and seedborne fungus that can cause significant losses on maize through a variety of different diseases, including seedling blight. Seedling blight is usually managed by utilizing fungicide seed treatments, but unfavorable germination environments and high levels of inoculum can still cause significant losses. Therefore, improved seed treatment efficacy is needed. Amphiphilic polyanhydride nanoparticles (PAN) have been used to enhance efficacy and provide sustained release of several active ingredients in animal systems and have potential for use in crop production.

To assess the potential benefits of PANs in seed treatment formulations, we performed two types of ...


Pest Management Of Soybean Aphid And Soybean Cyst Nematode: Host-Plant Resistance, Entomopathogens, And Seed-Applied Pesticides, Eric Harold Clifton Jan 2017

Pest Management Of Soybean Aphid And Soybean Cyst Nematode: Host-Plant Resistance, Entomopathogens, And Seed-Applied Pesticides, Eric Harold Clifton

Graduate Theses and Dissertations

Farmers can benefit from tools that are applied at planting and can still manage pest populations throughout the growing season. To meet these demands, some of the tools include host-plant resistance and seed-applied pesticides. However, prophylactic applications of pesticides in a seed treatment may not always be needed to preserve yield. The complex biology of induced plant defenses could also be exploited to make crops more tolerant to pest injury. Here we focus on two major soybean pests: soybean aphid, Aphis glycines Matsumura, and soybean cyst nematode, Heterodera glycines Ichinohe.

One field study was conducted in multiple years and locations ...


Development Of Methods To Study Plant-Parasitic Nematode Chemotaxis And The Effect Of Ilevo And Votivo Seed Treatments On The Soybean Cyst Nematode, Heterodera Glycines, Augustine Quirarte Beeman Jan 2017

Development Of Methods To Study Plant-Parasitic Nematode Chemotaxis And The Effect Of Ilevo And Votivo Seed Treatments On The Soybean Cyst Nematode, Heterodera Glycines, Augustine Quirarte Beeman

Graduate Theses and Dissertations

Nematode-protectant seed treatments for controlling the soybean cyst nematode, Heterodera glycines, have been introduced for integration into existing nematode management plans. Several seed treatments labeled for H. glycines control are currently available, with more expected in the near future. This dissertation describes i) tools to study nematode chemotaxis to chemicals and roots and ii) assessment of two commercial seed treatments, ILeVO (active ingredient: fluopyram) and VOTiVO (active ingredient: Bacillus firmus I-1582), on important H. glycines life processes.

The first objective was to develop and test two novel microfluidic chips to study chemotaxis of plant-parasitic nematodes to chemicals (“basic chip”) and ...


Investigation Of Soybean Susceptibility To Soybean Aphids And How Aphids Affect Plant-Mediated Pest Interactions, Jessica Hohenstein Jan 2017

Investigation Of Soybean Susceptibility To Soybean Aphids And How Aphids Affect Plant-Mediated Pest Interactions, Jessica Hohenstein

Graduate Theses and Dissertations

The soybean aphid (Aphis glycines) is an important insect pest of soybean (Glycine max). Previously, jasmonic acid (JA) was shown to elicit effective plant defense responses against soybean aphids. However, aphids were able to attenuate wound- or JA-induced responses in infested leaves in the compatible interaction and the mechanism of suppression remained uncharacterized. We hypothesized that aphids induce a decoy pathway to suppress plant defense responses and showed that aphids exploit the abscisic acid (ABA) pathway to suppress JA-mediated signaling. Both endogenous and exogenous ABA suppressed the wound-induced JA response. Furthermore, aphid populations were significantly reduced in the absence of ...


Evolution Of Duplicated Pathways And Networks In Polyploid Cotton, Joseph Patrick Gallagher Jan 2017

Evolution Of Duplicated Pathways And Networks In Polyploid Cotton, Joseph Patrick Gallagher

Graduate Theses and Dissertations

Polyploidy is an evolutionary phenomenon resulting in the duplication of the whole genome. The merger of two diverged genomes, in the case of allopolyploidy, had multiple effects on the evolution of genes, gene expression, and the structure of the newly doubled genome. Gene pathways and gene co-expression networks are also duplicated as a whole and must be reconciled in the nascent polyploid. A considerable body of work addresses how pathways and gene co-expression networks evolve in diploids. Here I extend this approach to address how duplicated pathways and networks evolve in polyploids.

The effects of polyploidy on gene pathways and ...


Sooty Blotch And Flyspeck: Taxonomy, Ecology, And Management, Hafizi Rosli Jan 2017

Sooty Blotch And Flyspeck: Taxonomy, Ecology, And Management, Hafizi Rosli

Graduate Theses and Dissertations

Sooty blotch and flyspeck (SBFS), a fungal disease of apple and other fruit crops, has been studied for 185 years because it can cause significant economic losses for growers. In recent years, with the deployment of phylogenetic analysis to complement morphological observation, many cryptic species of SBFS fungi have been discovered. For example, although the genus Peltaster has only two species, P. fructicola and P. cerophilus, potentially this cryptic genus has more undescribed species. Most commercial apple growers in the eastern half of the U.S. manage SBFS with fungicide sprays applied on a calendar-timed basis, spraying every 7 to ...


Membrane Trafficking In Resistance Gene-Mediated Defense Against The Barley Powdery Mildew Fungus, Priyanka Surana Jan 2017

Membrane Trafficking In Resistance Gene-Mediated Defense Against The Barley Powdery Mildew Fungus, Priyanka Surana

Graduate Theses and Dissertations

Blumeria graminis f. sp. hordei (Bgh) is the causal agent of powdery mildew on barley. Bgh secretes over 700 proteins that may function to modify host processes for colonization. Differential expression analysis of Bgh genes encoding secreted proteins in an isogenic panel of host immune signaling mutants, including a novel mutation Rar3 (Required for Mla6 Resistance3), identified fungal membrane trafficking genes. Infection phenotyping and kinetics show that immune compromised mutants have similar fungal growth, thereby, attributing any differences observed in expression to mutation rather than development. Thus, we hypothesize that powdery mildew genes may be targeting the host membrane trafficking ...


Genetic Regulation Of Aleurone Development In Zea Mays, Bryan Christopher Gontarek Jan 2017

Genetic Regulation Of Aleurone Development In Zea Mays, Bryan Christopher Gontarek

Graduate Theses and Dissertations

The general introduction including part of a book chapter (Chapter 1), a journal paper (Chapter 2), my side project (Chapter 3) and the general conclusions including part of a book chapter (Chapter 4) are included in this dissertation.

Chapter 2, in this chapter an analysis of NKD1 and NKD2 function in developing maize endosperm is described. We identify the DNA binding specificities of NKD1 and NKD2 and discern that NKD1 and NKD2 proteins can homo- and heterodimerize through their ID domains, and demonstrate they directly regulate transcription. RNA sequencing (RNAseq) analysis of nkd1 nkd2 versus wild type (WT) endosperm revealed ...


Molecular And Phenotypic Characterization Of Doubled Haploid Exotic Introgression Lines For Nitrogen Use Efficiency In Maize, Darlene Lonjas Sanchez Jan 2017

Molecular And Phenotypic Characterization Of Doubled Haploid Exotic Introgression Lines For Nitrogen Use Efficiency In Maize, Darlene Lonjas Sanchez

Graduate Theses and Dissertations

Nitrogen (N) is an important macroelement for promoting crop growth and development, and is essential for increased grain yield. However, less than half of the N fertilizer applied goes into the grain, and excess N goes back into the environment. Developing maize hybrids with improved nitrogen use efficiency (NUE) can help minimize N losses, and in turn reduce adverse ecological, economical, and health consequences. The root system plays a major role in the acquisition of N, as well as water and nutrients; thus, selecting for root architecture traits ideal for N uptake might help improve NUE in maize. This project ...


Soybean [Glycine Max (L.) Merr.] Agronomic Performance, Seed Characteristics, And Aconitase Isozymes Variability In Response To Environmental Stimuli, Grace Kaudzu Jan 2017

Soybean [Glycine Max (L.) Merr.] Agronomic Performance, Seed Characteristics, And Aconitase Isozymes Variability In Response To Environmental Stimuli, Grace Kaudzu

Graduate Theses and Dissertations

Environmental stimuli can generate intra-cultivar genetic variation in nearly homozygous soybean cultivars. This genetic variation may be useful for enhancing genetic diversity and developing new cultivars. Soybean plants exposed to multiple environmental stimuli produce seed variants with different phenotypic and genotypic characteristics. When these variants are selfed, the variation is heritable and stable. Seed produced in plants subjected to wide-spaced honeycomb (HC) planting, natural hail and to a modified accelerated aging (AA) at planting has exhibited intra-cultivar genetic variation. However, the effect of a single environmental stimulus on agronomic performance, seed characteristics and stability of variants from a soybean plant ...


Investigations Into Nutritional Quality, Commercial Productivity, And Genetic Purity Of Maize Grain For Organic Production Systems, Ryan Huffman Jan 2017

Investigations Into Nutritional Quality, Commercial Productivity, And Genetic Purity Of Maize Grain For Organic Production Systems, Ryan Huffman

Graduate Theses and Dissertations

Consumer demand for organic maize grain has steadily increased in the past decade which has resulted in an increased interest for this market class by plant breeders and geneticist. Each chapter in this dissertation investigates areas of concern to the organic community and possible solutions for improvement. Chapter 2 seeks to understand which combinations of genetic mechanisms are capable of a further increase in the methionine concentration of maize grain over individual mechanisms. Based on the genetic mechanisms evaluated, it was concluded that crosses combining dzr1 and recurrent selection in hybrid combination can elevate methionine concentration and overall grain nutritional ...


Gibberellin Biosynthesis By Bacteria And Its Effect On The Rhizobia-Legume Symbiosis, Ryan Stephan Nett Jan 2017

Gibberellin Biosynthesis By Bacteria And Its Effect On The Rhizobia-Legume Symbiosis, Ryan Stephan Nett

Graduate Theses and Dissertations

The gibberellin (GA) phytohormones are integral to many aspects of plant growth and

development. Perhaps due to the importance of GA signaling, many plant-associated

microbes, both fungal and bacterial, are also capable of producing GAs, presumably to

manipulate their plant host. The plant and fungal GA biosynthetic pathways have been well

studied and fully characterized, revealing that these organisms have convergently evolved the

ability to produce GA. However, GA biosynthesis in bacteria has remained elusive. Many

rhizobia, the bacterial, nitrogen-fixing symbionts associated with legumes, have been found

to contain a putative GA biosynthetic gene cluster/operon (GA operon). Through

characterization ...


Genetic Studies On Self-Fertility In Perennial Ryegrass (Lolium Perenne L.) With Implications For Hybrid Breeding In Allogamous Grasses, Javier Do Canto Fagundez Jan 2017

Genetic Studies On Self-Fertility In Perennial Ryegrass (Lolium Perenne L.) With Implications For Hybrid Breeding In Allogamous Grasses, Javier Do Canto Fagundez

Graduate Theses and Dissertations

Perennial grasses have diverse uses and are relevant from the agronomic and economic point of view, with main uses as forage, turf and bioenergy. In the grass family polyploidy is prevalent and both autopolyploids and allopolyploids are present. Also, within grasses there are a range of breeding systems, but hermaphrodite flower is the most frequent floral condition. Cross-pollination in species with hermaphrodite flowers is imposed by a gametophytic genetic self-incompatibility (SI). SI is controlled by two multiallelic and independent loci, S and Z. The incompatibility phenotype of the pollen grain is determined by its haploid genome. A pollen grain is ...


Genetic Architecture Of Antibiosis And Antixenosis Aphid Resistance In Soybean And Elucidation Of The Molecular Effect Of Pyramiding Rag1 And Rag2 Resistance Genes, Martha Ibore Jan 2017

Genetic Architecture Of Antibiosis And Antixenosis Aphid Resistance In Soybean And Elucidation Of The Molecular Effect Of Pyramiding Rag1 And Rag2 Resistance Genes, Martha Ibore

Graduate Theses and Dissertations

Soybean aphids are a major problem to soybean growers worldwide and they cause great yield losses. In the United States, soybean aphids can cause yield losses of up to 50% especially on susceptible varieties. Yield losses attributed to feeding by soybean aphids can be reduced by cultivating resistant soybean varieties. In recent years, certain biotypes of soybean aphids that can colonize resistant soybean plants have been reported, suggesting the continued need for identification of novel sources of aphid resistance to include in plant breeding programs. While gene pyramiding, in which certain resistant soybean genotypes carry more than one aphid resistance ...


Quantifying The Effects Of Crop-Cultural Practices On Growth And Development Of Herbaceous Annuals And Perennials In Novel Bioplastic Biocontainers, Nicholas Julian Flax Jan 2017

Quantifying The Effects Of Crop-Cultural Practices On Growth And Development Of Herbaceous Annuals And Perennials In Novel Bioplastic Biocontainers, Nicholas Julian Flax

Graduate Theses and Dissertations

Most commercially produced plant containers are manufactured from petroleum-based plastics. Plant containers typically have a short useful lifespan and are discarded into the solid-waste stream when no longer needed. This generates millions of pounds of residual plastic waste, and ultimately that waste enters the environment. Biocontainers are plant containers manufactured from a variety of bio-based materials and offer a more sustainable alternative to conventional petroleum-plastic pots in commercial horticulture. However, researchers have identified functional deficiencies in commercially available biocontainers that make them less desirable to commercial container-crop producers. Bioplastics and biocomposites can have physical properties similar to petroleum plastics, and ...


Soybean Root Rot Caused By Fusarium Oxysporum And Fusarium Graminearum: Interactions With Biotic And Abiotic Factors, David Ricardo Cruz Jimenez Jan 2017

Soybean Root Rot Caused By Fusarium Oxysporum And Fusarium Graminearum: Interactions With Biotic And Abiotic Factors, David Ricardo Cruz Jimenez

Graduate Theses and Dissertations

Fusarium oxysporum (Fo) and Fusarium graminearum (Fg) are important components of the Fusarium root rot complex in soybean. Fo is one of the species most frequently associated with soybean root rot, and Fg isolates that colonize wheat and maize have been found to be highly pathogenic on soybean, in the United States. Fo and Fg cause seed decay, damping-off, crown and root rots and pod blight.

The goal of this research was to characterize the biology of Fo and Fg and determine their role as soybean seedling pathogens in the Fusarium root rot complex. The objectives were to: i) assess ...


Genome Wide Association Study Of Seed And Seedling Root Traits In Sunflower, Ze Tian Fang Jan 2017

Genome Wide Association Study Of Seed And Seedling Root Traits In Sunflower, Ze Tian Fang

Graduate Theses and Dissertations

Cultivated sunflower (Helianthus annuus L.) is an internationally important crop harvested for seed oil and confectionary purposes. Sunflower unlike many other crops, has an extensive root system that can provide drought avoidance under water limiting conditions in the field. This genome wide association (GWA) study utilized 2D images of seeds and seedling roots from a diverse panel of sunflower genotypes (n = 288 lines) for QTL detection. The subsequent analyses of these images revealed vast phenotypic variation in total root length (mean = 169 cm, SD = 81 cm) and primary root length (mean = 29 cm, SD = 7 cm). ANOVA and PCA based ...


Production, Perceptions And Limitations Of Organic Small Grains In Iowa, David Weisberger Jan 2017

Production, Perceptions And Limitations Of Organic Small Grains In Iowa, David Weisberger

Graduate Theses and Dissertations

Small grains, such as, barley (Hordeum vulgare L.), oat (Avena sativa L.), rye (Secale cereale L.), triticale (X Triticosecale Wittmack) and wheat (Triticum aestivum L.) contribute to the proper functioning of organic row crop systems in Iowa and the upper Midwest. Besides producing grain and straw, which have value either as sold products or on-farm inputs, they are commonly used rotation crops that contribute functions such as forage legume establishment and weed suppression. Additionally, they may contribute to a suite of below ground functions that included soil quality improvement and disease suppression. However, small grains themselves are less profitable than ...


Efficacy Of Soybean Seed Treatments In Iowa And The Effect Of Cold Stress On Damping-Off Caused By Pythium Sylvaticum, Mauricio Serrano Jan 2017

Efficacy Of Soybean Seed Treatments In Iowa And The Effect Of Cold Stress On Damping-Off Caused By Pythium Sylvaticum, Mauricio Serrano

Graduate Theses and Dissertations

Soybean (Glycine max (L.) Merr.) production is negatively affected by the occurrence of seedling diseases. In Iowa, the occurrence of seedling diseases is commonly associated with cool and wet weather soon after planting, and several Pythium spp. have been found as the predominant pathogens causing seedling disease. Increasing cost of the seed, risk of seedling diseases reducing stand in cold, wet soils, and the yield benefit sometimes provided by early planting have motivated an increase in the use of fungicide seed treatment. However, a positive effect of seed treatments on soybean plant stand and yield has not been clearly demonstrated ...


The Horticultural Potential Of Six Species Of North American Hickories, Brandon Michael Miller Jan 2017

The Horticultural Potential Of Six Species Of North American Hickories, Brandon Michael Miller

Graduate Theses and Dissertations

The genus Carya is largely composed of taxa endemic to eastern North America. This entire group of long-lived, durable, and aesthetically pleasing trees has been ignored by horticulturists because of issues related to their production as well as performance in the nursery and landscape. Hickories develop large, dominant taproots and supposedly produce few lateral roots, which are often associated with increased transplant success. Hickory seedlings are also considered to exhibit a lag phase in shoot growth, an additional disadvantage that hinders their production. The main objectives of the research presented in this document were to explore potential production methods that ...