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  • 1. Kannberg, Seth The Effects of Planting Date on Soybean Grain Yield Grown within a Rye Cover Crop System

    Master of Science, The Ohio State University, 2023, Horticulture and Crop Science

    When attempting to maximize soybean yield it is vital to analyze the interactions that occur between planting date and cover crop presence. Research has consistently shown that planting date has the greatest influence on soybean grain yield. However, studies testing for how early soybean can realistically be planted and impacts that may result from such a planting are non-existent. Therefore, the objectives of this study were to 1) determine the yield impact when growing soybean with or without a rye cover crop for three different planting dates and 2) to measure the survivability of soybean seedlings at each planting. A field experiment was conducted at two locations within Ohio in South Charleston and Wooster for the 2021 and 2022 growing seasons. A randomized complete block design was utilized consisting of four replications with nine treatments. The two factors examined were planting date and cover crop presence along with termination timing. Herbicide burndown of the cover crop was coordinated with the planting date of each soybean group. Plant population over time, soil temperature along with percent moisture over time, soybean yield, and rye biomass dry weight were evaluated. Plant populations were between 25% and 42% greater as planting was delayed into May and the best stands were achieved by forgoing a cover crop. However, the treatments with the greatest plant populations planted in May did not result in a yield advantage compared to the plantings in early or late April. When planting ultra-early prior to 15 April, a cover crop proved unnecessary and should be avoided. Planting ultra-early with a cover crop resulted in significant yield declines across both locations of between 24% and 59% compared to planting ultra-early without a cover crop.
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    Committee: Laura Lindsey (Advisor); Alex Lindsey (Committee Member); Marilia Chiavegato (Committee Member) Subjects: Agriculture; Agronomy

  • 2. Ng, Sin Joe The Effect of Mid-season Foliar Fungicide and Insecticide, Applied Alone or in Combination, on Soybean Yield in Ohio

    Master of Science, The Ohio State University, 2017, Horticulture and Crop Science

    Ohio soybean farmers are very concerned about disease and insect pressure during the midseason that may impact yield. The impact of mid-season management for foliar diseases and insect feeding on grain yield was studied in a series of field experiments. The first objective was to evaluate the effect of mid-season foliar fungicide and insecticide application on soybean yield, applied alone or in combination. A trial was established at 12 on-farm field site-years in Ohio during 2015 and 2016 in a randomized complete block design with four replications per treatment. Fungicide and insecticide treatments included: 1) nontreated control, 2) fungicide alone, 3) insecticide alone, 4) fungicide plus insecticide (tank-mixed), 5) fungicide and insecticide (separate tank), 6) fungicide plus crop oil, 7) insecticide plus crop oil, 8) fungicide, insecticide plus crop oil (tank-mixed). All treatments were applied at R3 growth stage (initial pod development), and data on the percent leaf area affected by foliar diseases and insect defoliation was collected. There was no significant yield response associated with insecticide application due to low insect pressure and low insect defoliation levels at the time of insecticide application at all 12 site-years. However, at the end of the growing season, the number of bean leaf beetles (2-22) and pod injury caused by their feeding (4.1-37%) were high at 4 out of 12 site-years. Fungicide application alone had significantly (P<0.05) higher yield of 4 to 8 bushel/acre at 4 of 12 site-years due to the high leaf area affected in the canopy from Septoria glycines and Cercospora sojina which cause brown spot and frogeye leaf spot disease, respectively. The mean yield from plots treated with a tank-mixture of fungicide and insecticide was not significant difference from those treated with the fungicide alone. In this study, insecticide applications were applied too early in the growing season to have an impact on late-season pod feeding. Based o (open full item for complete abstract)
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    Committee: Laura Lindsey (Advisor); Anne Dorrance (Committee Member); Andrew Michel (Committee Member) Subjects: Agriculture; Agronomy; Entomology; Plant Pathology; Plant Sciences

  • 3. Menke, Mark Suppression of purple deadnettle (Lamium purpureum) and soybean cyst nematode (Heterodera glycines) with a fall cover crop of Italian ryegrass, (Lolium multiflorum) /

    Master of Science, The Ohio State University, 2008, Graduate School

    Committee: Not Provided (Other) Subjects:

  • 4. Huynh, Ngoc Thien Tu Development of Genetic Resources and Tools for Characterizing and Improving the Traits of Seed Oil and Protein Contents in Soybean

    Doctor of Philosophy, The Ohio State University, 2024, Horticulture and Crop Science

    Soybean, a vital oilseed crop and protein meal source, plays an important role in the global economy and food supply. It serves as a major source of vegetable oil and primary protein for swine and poultry feed due to its unique seed compositions. However, challenges arise from the negative correlation between oil and protein contents, and between yield and protein content, posing challenges to developing cultivars with high yield, high oil, and high protein contents. Despite extensive studies on the biochemistries of these traits, the complexities persist, driving the need for advancements in breeding and biotechnology. Efforts and progress in using genetics and biotechnology to understand and modulate soybean traits were reviewed in Chapter 1. To contribute to such collective efforts, in my study, I utilized breeding and biotechnology techniques to develop genetic resources and tools for characterizing and improving the traits of seed oil and protein contents. In Chapter 2, I examined singleand multiple-trait methods for quantitative trait locus (QTL) analyses using recombinant inbred populations with elite backgrounds. The project revealed that single-trait QTL analysis was sufficient for high-heritability traits like seed oil and protein contents and provided QTLs for marker-assisted selection and possibilities to determine their allelic effects on yield, thanks to the elite pedigree. Candidate genes were identified from the QTLs for functional analysis. The lack of tools for efficient gene characterization in soybean seed traits was addressed in Chapter 3 through a proposed CRISPR/Cas9-mediated gene silencing method via particle bombardment of embryogenic tissues. The approach holds the potential for rapid gene functional characterization by bypassing the need for full plant regeneration. Though the project yielded negative results, most likely due to low transformation frequency in soybean, more optimizations could be tested to improve the too (open full item for complete abstract)
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    Committee: Leah McHale (Advisor); Jonathan Fresnedo-Ramirez (Committee Member); Jyan-Chyun Jang (Committee Member); John Finer (Committee Member); Feng Qu (Committee Member) Subjects: Agriculture; Genetics; Plant Sciences

  • 5. Moore, Jenna Effects of Soybean Seeding Rate on Plant-to-Plant Variability, Yield, and Soybean Cyst Nematode

    Master of Science, The Ohio State University, 2021, Horticulture and Crop Science

    Over 80 million acres of soybean were planted in the United States in 2020. The cost of soybean seed has increased by 65% from 2000 to 2019, making the average cost of seed per acre $56.10 in 2019. The increasing cost of seed, along with recent studies suggesting that lower seeding rates achieve similar yields and provide a higher return on investment, has prompted interest in optimizing seeding rate. There is often a discrepancy between soybean seeding rate and final soybean stand that is attributed to both abiotic and biotic factors. In other crops, plant competition as a result of population density can result in variations in aboveground and fine-root biomass, nutrient composition, and yield. The objectives of this research were to 1) determine how soybean seeding rate impacts biomass accumulation and nutrient composition, 2) determine how seeding rate and stand evenness influences soybean yield and 3) determine when soybean is most susceptible to stand reduction. For these objectives, six on-farm trials were established in 2019 and 2020. Treatments included seeding rate (from 80,000 seeds/acre to 250,000 seeds/acre). Soybean population, spatial variability, and growth stage were recorded every 14-21 days. Aboveground biomass, belowground fine-root biomass, and yield were collected at physiological maturity. Aboveground biomass, belowground fine-root biomass, and yield were collected at physiological maturity. There were minimal differences in aboveground biomass among the seeding rate treatments, aligning with other research that suggests soybean is highly plastic in its ability to compensate for lower seeding rates. Fine-root production was not impacted by population density, but biomass did vary from year-to-year.. Yield improvements from increased seeding rates occurred at three of six site-years and resulted in yield advantages of 4.2-9.3 bu/ac. At four site-years, lower seeding rates (80,000-120,000) resulted in a higher stand reduction compared to higher (open full item for complete abstract)
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    Committee: Laura Lindsey (Advisor); Anne Dorrance (Committee Member); Christine Sprunger (Committee Member); Elizabeth Hawkins (Committee Member) Subjects: Agriculture; Agronomy; Plant Biology; Plant Pathology; Plant Sciences; Soil Sciences

  • 6. Li, Shang-Min Utilization of Pyrolyzed Soybean Hulls as an Alternative Reinforcement Filler in Natural Rubber Compounds

    Master of Science in Polymer Engineering, University of Akron, 2021, Polymer Engineering

    Soybean has become one of the major food resources nowadays. Increased cultivation results in large amount of side products, such as soybean hulls and stems which can be used for variety of purposes. By using pyrolysis processes which thermally decompose the material in an inert environment, soybean hulls are converted into the carbon-rich black fillers. This research investigates the effectiveness of pyrolyzed soybean hulls (PSBH) as an alternative eco-friendly reinforcement filler to replace carbon black (CB) in natural rubber compounds. For this purpose, carbon black was replaced by four types of PSBH with weight percent varying from 0% to 35%. Ball milling of PSBH was performed to investigate the effect of size reduction on the mechanical properties of natural rubber compounds. Among two types of PSBH pyrolyzed at 450℃ (A) and at 500℃ (B), ball milled PSBH B filled natural rubber vulcanizates obtained the higher tensile strength values, but the values were still inferior to the pure CB filled counterparts. Bound rubber measurement and swelling experiments were carried out to evaluate the interaction between fillers and rubber polymer chains. Using dynamic mechanical analysis (DMA), it was determined that addition of PSBH into rubber compounds resulted in lower wet-skid resistance while improving the rolling resistance.
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    Committee: Erol Sancaktar PhD (Advisor); Kevin Cavicchi PhD (Committee Chair); Sadhan Jana PhD (Committee Member) Subjects: Polymers

  • 7. Bhadriraju, Vamsi ENZYME-BASED PRODUCTION OF NANOCELLULOSE FROM SOYBEAN HULLS AS A GREEN FILLER FOR RUBBER COMPOUNDING

    Master of Science, University of Akron, 2020, Chemical Engineering

    Nanocellulose has been investigated for use in food packaging, biomedical applications, and electronics. This work attempted to isolate and evaluate crystalline nanocellulose from soybean hulls in the form of cellulose nanofibrils (CNFs) as reinforcing fillers in natural rubber composites. CNFs and nanocrystalline cellulose (CNCs) have previously been derived from different types of lignocellulosic biomass. Previous work in this area used alkali pretreatments and acid hydrolysis to break down the complex network of cellulose, hemicellulose, and lignin present in plant cell walls. CNCs and CNFs have previously been isolated using high shear microfluidization, cryocrushing, freeze drying, and ultrafiltration. In this work, enzyme cocktails of carbohydrases produced from Aspergillus niger were used to hydrolyze the polysaccharides in soybean hull and soybean flour. Solids were separated from soluble sugars and other components after enzyme hydrolysis for 24 hours, and these washed solids were treated with sonication, blending, and homogenization to reduce the size of these solids. Particle size analysis showed that enzyme hydrolysis did indeed generate nanoparticles, the majority of which were between 150-200 nm. The quantity of these insoluble nanoparticles was found to be small, however, relative to that of solids and seed coat fragments approximately 100-200 µm in length. Further analysis with microscopy and SEM imaging revealed that the enzyme hydrolysis was able to cleave sclereid structures from the seed coat and breakdown soybean hull into fragments. Smaller particle size loading at the beginning of enzyme hydrolysis was found to release more sugar, so intermediate sizes were sieved in order to maximize solids recovery and minimize sugar release. These washed and mechanically treated solids were next mixed at alkaline pH (9.8–10) with natural rubber latex and oven dried overnight to create rubber composites. The resulting composites were masticated, vulcanized, (open full item for complete abstract)
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    Committee: Lu-Kwang Ju (Advisor); Jie Zheng (Committee Member); Qixin Zhou (Committee Member) Subjects: Chemical Engineering

  • 8. Stewart, Ashley Molecular interactions among soybean aphids and aphid-resistant soybean

    Doctor of Philosophy, The Ohio State University, 2019, Translational Plant Sciences

    To survive on plant species, insects must continually adapt to the physical and chemical resistance mechanisms deployed by plants to prevent herbivory. In agricultural systems, plants with host-plant resistance (HPR) are bred to have naturally occurring resistance gene(s) that provide enhanced protection against insect pests. Host-plant resistance is an important component of integrated pest management (IPM), providing environmentally and economically safe protection against insect pests. However, insects that have adapted to HPR (i.e., virulent) threaten HPR durability. Host-plant resistance can be used in soybean to manage the soybean aphid (Aphis glycines), which is an important insect pest in the Midwestern U.S. The soybean resistance genes are known as Rag genes (resistant to Aphis glycines). However, virulent aphid biotypes that have adapted to HPR threaten the durability of Rag genes. The molecular mechanisms underlying aphid virulence are mostly unknown, but may involve effector proteins that are secreted in aphid saliva to suppress plant defenses. We reviewed effectors and other possible mechanisms of insect adaptation in Chapter 2. A better understanding of the mechanisms underlying aphid virulence will inform insect resistance management (IRM) models to delay the spread of virulence, thereby preserving HPR durability. To better understand which genes promote virulence in the soybean aphid, we profiled gene expression in avirulent and virulent aphids fed susceptible or Rag1+Rag2 resistant soybean (Chapter 3). There were many transcriptional differences between aphid biotypes, and many were constitutively different. Virulent aphids transcriptionally activated transposable elements and nearby genes, suggesting that there may be an epigenetic component to virulence. Additionally, aphids differentially expressed up to 40% of putative effectors, and most were down regulated in virulent compared to avirulent aphids, especially when aphids were fed suscepti (open full item for complete abstract)
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    Committee: Andy Michel (Advisor); Joshua Blakeslee (Advisor); John Finer (Committee Member); Susannah Cooper (Committee Member); Kelley Tilmon (Committee Member); Feng Qu (Committee Member) Subjects: Entomology

  • 9. Esquivel Palma, Carlos TOXICOLOGICAL INTERACTIONS BETWEEN THIAMETHOXAM, APHIDS, AND PREDATORY NATURAL ENEMIES

    Doctor of Philosophy, The Ohio State University, 2019, Entomology

    Insecticides are important tools for insect pest control in various agricultural systems. Currently, neonicotinoids are one of the most widely used insecticides. In particular, thiamethoxam is extensively used in crops for the control of several insect pests, including aphids. In field crops such as soybean, thiamethoxam is applied as seed treatment for the control of the soybean aphid (Aphis glycines) Matsumura (Aphididae: Hemiptera), an important invasive pest of soybean in North America. To date, however, it is unknown when and how quickly soybean aphid populations could increase after planting. Moreover, it is not clear whether seed treatments can control soybean aphid populations that are virulent to host-plant resistance. Determining the survival of soybean aphids over time and the capacity to control virulence on seed-treated soybean is crucial to improve soybean aphid control and virulence management. While thiamethoxam has shown to be effective against aphids, it could also cause negative effects on beneficial insects. One of the least understood ways thiamethoxam can harm beneficial insects is when predators consume aphids that have fed on plants treated with thiamethoxam (i.e. via the trophic food chain). Two important aphid predators, the convergent lady beetle (Hippodamia convergens) (Coleoptera: Coccinellidae) and the insidiosus flower bug (Orius insidiosus) (Anthocoridae: Hemiptera) have not been investigated for trophic food chain toxicity via prey (i.e. aphids). Furthermore, there is minimal information about the acute toxicity of insecticides on these predators. Therefore, the goals of this dissertation are 1) evaluate the durability of thiamethoxam seed treatment for the control of avirulent and virulent soybean aphids; 2) evaluate the effectiveness of thiamethoxam seed treatment for the control of soybean virulence; 3) estimate the toxicity thiamethoxam could have via the food chain on the convergent lady beetle and insidiosus flower bug; a (open full item for complete abstract)
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    Committee: Andy Michel PhD (Advisor); Luis Canas PhD (Advisor); Bill Hendrix PhD (Committee Member); Kelley Tilmon PhD (Committee Member); Reed Johnson PhD (Committee Member) Subjects: Agriculture; Agronomy; Entomology; Toxicology

  • 10. Pellegrene, Brittany Modification of Alkyd Resins and Seed Oil Based Reactive Diluents for High Performance Coatings

    Doctor of Philosophy, University of Akron, 2019, Polymer Engineering

    Alkyds, one of the most commonly used binders for coating systems, are modified polyesters derived from seed oils. They find utility in several coating applications, including architectural, industrial and wood coatings. Formulation involves the use of reactive diluents to decrease the viscosity and trigger the autoxidative curing mechanism of the alkyds to avoid the use of volatile organic compounds (VOCs). This work studies the modification of alkyds and reactive diluents and the differences between the coating performance of these additives. Two differently functionalized alkyds and reactive diluents were synthesized and formulated into high solids alkyds coatings. Alkoxysilane and fluorine functionalities were chosen to improve adhesion, hardness, and chemical and corrosion resistance of the coating system. The resulting coatings were analyzed for performance, tensile properties, corrosion resistance and weatherability. ESEM-EDX was used to observe the distribution of the fluorine and alkoxysilane in the cross-section of the coating. Stratification was observed for the modified reactive diluents at high concentrations, and these coatings showed improved adhesion and corrosion resistance. The modified alkyds performed better in terms of mechanical properties, but stratification was not observed. Next, the moisture sensitivity of alkoxysilanes was studied by looking into the effect of various relative humidity conditions on the curing and performance of alkoxysilane functionalized alkyd coatings. These coatings were evaluated for drying time, adhesion, hardness and mechanical properties. At high humidity, the alkoxysilane functional reactive diluents dried more quickly and formed harder coatings than the unmodified control. The functionalized alkyds showed enhanced adhesion and tensile strength at high humidity. Thirdly, fluorinated alkyds and reactive diluents were compared to understand the effects of molecular weight and viscosity on the stratification (open full item for complete abstract)
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    Committee: Mark Soucek PhD (Advisor); Thein Kyu PhD (Committee Chair); Younjin Min PhD (Committee Member); Tianbo Liu PhD (Committee Member); Chelsea Monty-Bromer PhD (Committee Member) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers

  • 11. Manuel, Juliana Weed hosts of soybean cyst nematode Heterodera glycines Ichinohe, 1952 /

    Doctor of Philosophy, The Ohio State University, 1983, Graduate School

    Committee: Not Provided (Other) Subjects: Agriculture

  • 12. Chen, Anthony Investigation of the parameters affecting the functionality and qualities of soy proteins in extraction process /

    Doctor of Philosophy, The Ohio State University, 1978, Graduate School

    Committee: Not Provided (Other) Subjects: Agriculture

  • 13. Bedestenci, Halil Foreign market demand for U.S. soybeans and soybean products : a policy approach /

    Doctor of Philosophy, The Ohio State University, 1978, Graduate School

    Committee: Not Provided (Other) Subjects: Economics

  • 14. Saxena, Naresh Viscoelastic characterization of soybean grain under quasi-static loading /

    Doctor of Philosophy, The Ohio State University, 1972, Graduate School

    Committee: Not Provided (Other) Subjects: Engineering

  • 15. Vig, Baldev Experimental alterations of leaf spot frequencies in Glycine max (L.) Merrill, with reference to the mechanism of spot formation /

    Doctor of Philosophy, The Ohio State University, 1967, Graduate School

    Committee: Not Provided (Other) Subjects: Biology

  • 16. Bluck, Grace Soybean Yield Response in High and Low Input Production Systems

    Master of Science, The Ohio State University, 2015, Horticulture and Crop Science

    From 2000 to 2013 soybean [Glycine max (L.) Merr] grain commodity price has increased by almost 300% generating interest in agricultural inputs to maximize soybean yield. The objective of this study was to evaluate the effect of common inputs on soybean grain yield in enhanced (high-input) and traditional (low-input) production systems. The inputs evaluated included: Rhizobia inoculant, gypsum, pyraclostrobin fungicide, lambda-cyhalothrin insecticide, and manganese (Mn) foliar fertilizer. A sixteen site-year trial was established in Ohio during 2013 and 2014. Rhizobia inoculant was seed applied before planting, gypsum was applied at the VC growth stage (unrolled unifoliate leaves), and fungicide, insecticide, and Mn foliar fertilizer were applied at the R3 growth stage (initial pod development). Measurements of percent leaf area affected by foliar disease and insect defoliation and Mn and sulfur (S) concentration in leaves were collected at six site-years. The omission of pyraclostrobin from the enhanced production system significantly reduced yield in five of sixteen site-years by 0.21 to 0.79 Mg ha-1, but its addition to a traditional system increased yield significantly at only one of sixteen site-years by 0.47 Mg ha-1 Soybean yield was influenced by fungicide application when fields had disease present, above average yield (>3.5 Mg ha-1), and received >25 cm of precipitation in June and July. During 2013 and 2014, with established corn/soybean rotations, no S or Mn deficiencies, and minimal insect pressure, there were limited effects of inoculant, gypsum, insecticide, and Mn foliar fertilizer on grain yield. The data indicate a very small potential for high-input production systems to enhance crop yield without the presence of diseases, insects, or nutrient deficiencies. Knowledge of potential yield limiting factors is useful in identifying inputs that will increase soybean yield on a field by field basis.
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    Committee: Laura Lindsey (Advisor); Anne Dorrance (Committee Member); Jim Metzger (Committee Member) Subjects: Agriculture; Agronomy; Plant Pathology; Plant Sciences

  • 17. Gunadi, Andika Characterization of Rps8 and Rps3 Resistance Genes to Phytophthora sojae through Genetic Fine Mapping and Physical Mapping of Soybean Chromosome 13

    Master of Science, The Ohio State University, 2012, Plant Pathology

    Dominant race-specific resistance genes in soybean [Glycine max (L.) Merrill] is a major component in the management of the root and stem rot pathogen Phytophthora sojae Kaufmann and Gerdemann. Several of these resistance genes, namely Rps3a, Rps3b, Rps3c and Rps8 were mapped in previous studies within the vicinity of a resistance-gene-rich region on the long arm of soybean chromosome 13. These genes provide valuable resources for breeding elite soybean cultivars with extended lifetime of resistance to P. sojae. However, a more precise determination of the relationship among these genes, as well as their cloning are necessary for expediting breeding efforts involving gene stacking of resistance genes from chromosome 13. In the first part of this study, allelism studies and linkage analysis were performed to elucidate the genetic distance and the positioning of Rps3a, Rps3c and Rps8. Isolates of P. sojae with virulence patterns specific for avirulence to all 3 genes as well as avirulence or virulence corresponding to one gene or another were used to evaluate the disease resistance within F2:3 and F3:4 mapping populations derived from crosses of soybean genotypes with Rps3a and Rps8, as well as Rps3c and Rps8. The second part of this study involved the screening of Bacterial Artificial Chromosome (BAC) libraries and the sequencing of selected BAC clones for the development of physical map of Rps3a and Rps8 genetic region. The allelism studies suggest that Rps3a and Rps8 are linked at a genetic distance of greater than or equal to 11.0 cM, while Rps3c and Rps8 are not linked. Preliminary genetic linkage maps of the long arm of chromosome 13 have been successfully developed from L83-570 (Rps3aRps3a) PI 399073 (RpsNRpsNRps8Rps8) and L92-7857 (Rps3cRps3c) PI 399073 F3:4 populations. In this study, Rps8 was mapped to a previously reported location in chromosome 13, north of the simple sequence repeat marker Satt114, and flanked by markers Sat_103 and Sat_234. Highly signif (open full item for complete abstract)
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    Committee: Anne Dorrance PhD (Advisor); Margaret Redinbaugh PhD (Committee Member); Leah McHale PhD (Committee Member) Subjects: Agriculture; Bioinformatics; Biology; Botany; Evolution and Development; Genetics; Molecular Biology; Plant Biology; Plant Pathology; Plant Sciences

  • 18. Orantes, Lucia Population Genetics of Soybean Aphid: Elaborating Species Specific SNPs to test Bottleneck and Migration Hypotheses across North-central US and Canada

    Master of Science, The Ohio State University, 2011, Entomology

    Since its introduction in 2000 to North America, the soybean aphid (Aphis glycines) has spread across much of the U.S. and Canadian soybean growing regions, and has become one of the most damaging insect pests of this crop. Such rapid and large-scale pattern suggests that A. glycines has high rates of adaptability and dispersal. These trends have been linked to the effect of host transition, and the ability of aphid populations to clone and migrate across soybean fields during summer. The soybean aphid is a holocyclic insect that alternates between two hosts: (1) buckthorn, where sexual reproduction, oviposition and overwintering occur; and (2) soybean, where clonal reproduction and large-scale migration occur. We conducted a study using eight North American locations where aphids were collected twice, early and late in the soybean season. To analyze the genetic structure of the sampled populations, we used six microsatellite markers, and developed and validated twenty-four Single Nucleotide Polymorphic markers. These markers are, to my knowledge, the first SNPs to be validated for soybean aphid. The objective for the study was to analyze the genetic structure of soybean aphid populations during the transition from buckthorn to soybean in spring, and the progressive changes in the genetics of these populations after clonal reproduction and migration. The hypotheses from the study were that (1) soybean aphids go through population bottlenecks that differentiate population at the beginning of the season, and (2) there is a large-scale dispersion of aphids across soybean fields once the aphids have reached a population outbreak. Results from the study showed strong population differentiation among early populations and supported the hypothesis of large-scale dispersal among late populations, demonstrating that indeed there is a continuous change in the genetic structure of the soybean aphid explained through the migratory behavior of the aphids. Future studies are need (open full item for complete abstract)
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    Committee: Andrew Michel (Advisor); Lisle Gibbs (Committee Member); Mary Gardiner (Committee Member) Subjects: Agriculture

  • 19. Choi, Suk-won The potential and cost of carbon sequestration in agricultural soil: empirical study of dynamic model in the midwestern U.S

    Doctor of Philosophy, The Ohio State University, 2004, Agricultural, Environmental and Development Economics

    This study investigates the cost and potential of carbon sequestration in agricultural soil in the Midwest U.S. Previous economic studies ignored several important features such as the range of residue management intensity, dynamic soil carbon properties, cyclical crop rotation patterns, alternatives on the baseline scenarios, and spatial pattern of carbon gains. Developing the empirical dynamic model that maximizes the net present value of market welfare on corn and soybean, two different carbon programs are applied: carbon renting program and fixed payment per hectare with minimum residue intensity. Several empirical estimations are employed to obtain parameters for the dynamic model, in particular, residue management impacts on crop yield and carbon dynamics. The crop yield loss by conservation practice is greater in high quality soil than the low quality class. Sensitivity analysis on different baseline scenario suggests that carbon sequestration path could be altered by different assumptions. It suggests that the estimates of the carbon gains from any carbon policy would be sensitive by how baseline scenario is assumed. In general, the adoption rate of conservation practice is higher in soybean and low quality soil classes than in corn and high quality soil classes. Carbon renting analysis shows that corn price could rise and soybean price could decrease, but the magnitude is not immense. Overall, the average cost of carbon sequestration is the lowest with carbon renting policy and the highest with fixed payment per hectare with low minimum residue management requirement. The average cost rages from $0.06 to $4.50 per ton with carbon renting scenario. With fixed payment scenario, the average cost rises to $40-$613 per ton with 35 % residue management and $18-$304 per ton with 75% requirement. The area with high yield potential does not necessarily provide the carbon gains because the residue management intensity is minimal at 35 %. The source of carbon gains in (open full item for complete abstract)
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    Committee: Brent Sohngen (Advisor) Subjects: Economics, Agricultural

  • 20. Walker, Robert The Effects of drying on soybean germination and seed coat cracks /

    Master of Science, The Ohio State University, 1972, Graduate School

    Committee: Not Provided (Other) Subjects: