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Iowa State University

Soybean

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Genetic Architecture Of Charcoal Rot (Macrophomina Phaseolina) Resistance In Soybean Revealed Using A Diverse Panel, Sara M. Coser, R. V. Chowda Reddy, Jiaoping Zhang, Daren S. Mueller, Alemu Mengistu, Kiersten A. Wise, Tom W. Allen, Arti Singh, Asheesh K. Singh Sep 2017

Genetic Architecture Of Charcoal Rot (Macrophomina Phaseolina) Resistance In Soybean Revealed Using A Diverse Panel, Sara M. Coser, R. V. Chowda Reddy, Jiaoping Zhang, Daren S. Mueller, Alemu Mengistu, Kiersten A. Wise, Tom W. Allen, Arti Singh, Asheesh K. Singh

Agronomy Publications

Charcoal rot (CR) disease caused by Macrophomina phaseolina is responsible for significant yield losses in soybean production. Among the methods available for controlling this disease, breeding for resistance is the most promising. Progress in breeding efforts has been slow due to the insufficient information available on the genetic mechanisms related to resistance. Genome-wide association studies (GWAS) enable unraveling the genetic architecture of resistance and identification of causal genes. The aims of this study were to identify new sources of resistance to CR in a collection of 459 diverse plant introductions from the USDA Soybean Germplasm Core Collection using field and ...


The Effect Of Five Biomass Cropping Systems On Soil-Saturated Hydraulic Conductivity Across A Topographic Gradient, Lisa A. Schulte-Moore, Matthew J. Helmers, Randall K. Kolka Sep 2017

The Effect Of Five Biomass Cropping Systems On Soil-Saturated Hydraulic Conductivity Across A Topographic Gradient, Lisa A. Schulte-Moore, Matthew J. Helmers, Randall K. Kolka

Agricultural and Biosystems Engineering Publications

Understanding the environmental impact of bioenergy crops is needed to inform bioenergy policy development. We determined the effects of five biomass cropping systems—continuous maize (Zea mays), soybean (Glycine max)-triticale (Triticosecale ×)/soybean-maize, maize-switchgrass (Panicum virgatum), triticale/sorghum (Sorghum bicolor), and triticale-aspen (Populus alba × P. grandidentata)—on soil-saturated hydraulic conductivity (K S ) across a toposequence in central Iowa, USA. We compared data from the time of cropping system establishment in 2009 to 4 years post-establishment. Both our 2009 and 2013 data confirmed that cropping system impacts on K S vary by landscape position. We found that differences in cropping system ...


Isolation And Characterization Of The Aconitate Hydratase 4 (Aco4) Gene From Soybean, Z Coleman, J. Boelter, K. Espinosa, A. S. Goggi, R. G. Palmer, D. Sandhu Feb 2017

Isolation And Characterization Of The Aconitate Hydratase 4 (Aco4) Gene From Soybean, Z Coleman, J. Boelter, K. Espinosa, A. S. Goggi, R. G. Palmer, D. Sandhu

Agronomy Publications

Aconitase catalyzes the reversible isomerization of two tricarboxylic acids, citrate and isocitrate, during the Krebs cycle. Five aconitase genes, namely, Aco1, Aco2, Aco3, Aco4, and Aco5, have been identified in soybean. Previously, Aco4 was mapped on chromosome 11. The purpose of this investigation was to isolate and sequence the candidate gene for Aco4. We mapped the Aco4 gene to a 148 kb region on chromosome 11 that contained 19 predicted genes. One of these, Glyma.11G080600, codes for aconitate hydratase. Sequencing of two isozyme variants (A-line and B-line) for Glyma.11G080600 revealed three synonymous and two non-synonymous substitutions. Perhaps, the ...


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 ...


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 ...


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 ...


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 ...


Advancing Our Understanding Of Charcoal Rot In Soybeans, Martha P. Romero Luna, Daren Mueller, Alemu Mengistu, Asheesh K. Singh, Glen L. Hartman, Kiersten A. Wise Jan 2017

Advancing Our Understanding Of Charcoal Rot In Soybeans, Martha P. Romero Luna, Daren Mueller, Alemu Mengistu, Asheesh K. Singh, Glen L. Hartman, Kiersten A. Wise

Agronomy Publications

Charcoal rot [Macrophomina phaseolina (Tassi) Goid] of soybean [Glycine max (L.) Merr.] is an important but commonly misidentified disease, and very few summary articles exist on this pathosystem. Research conducted over the past 10 yr has improved our understanding of the environment conducive to disease development, host resistance, and improved disease diagnosis and management. This article summarizes the currently available research with an emphasis on disease management.


Soybean Proteins Gmtic110 And Gmpsbp Are Crucial For Chloroplast Development And Function, Devinder Sandhu, Taylor Atkinson, Andrea Noll, Callie Johnson, Katherine Espinosa, Jessica Boelter, Stephanie Abel, Balpreet K. Dhatt, Terese Barta, Eric Singsaas, Sol Sepsenwol, A. Susana Goggi, Reid G. Palmer Nov 2016

Soybean Proteins Gmtic110 And Gmpsbp Are Crucial For Chloroplast Development And Function, Devinder Sandhu, Taylor Atkinson, Andrea Noll, Callie Johnson, Katherine Espinosa, Jessica Boelter, Stephanie Abel, Balpreet K. Dhatt, Terese Barta, Eric Singsaas, Sol Sepsenwol, A. Susana Goggi, Reid G. Palmer

Agronomy Publications

We have identified a viable-yellow and a lethal-yellow chlorophyll-deficient mutant in soybean. Segregation patterns suggested single-gene recessive inheritance for each mutant. The viable- and lethal-yellow plants showed significant reduction of chlorophyll aand b. Photochemical energy conversion efficiency and photochemical reflectance index were reduced in the viable-yellow plants relative to the wildtype, whereas the lethal-yellow plants showed no electron transport activity. The viable-yellow plants displayed reduced thylakoid stacking, while the lethal-yellow plants exhibited failure of proplastid differentiation into normal chloroplasts with grana. Genetic analysis revealed recessive epistatic interaction between the viable- and the lethal-yellow genes. The viable-yellow gene was mapped ...


Smos Optical Thickness Changes In Response To The Growth And Development Of Crops, Crop Management, And Weather, Brian K. Hornbuckle, Jason C. Patton, Andy Vanloocke, Andrew E. Suyker, Matthew C. Roby, Victoria A. Walker, Eswar R. Iyer, Daryl E. Herzmann, Erik A. Endacott Jul 2016

Smos Optical Thickness Changes In Response To The Growth And Development Of Crops, Crop Management, And Weather, Brian K. Hornbuckle, Jason C. Patton, Andy Vanloocke, Andrew E. Suyker, Matthew C. Roby, Victoria A. Walker, Eswar R. Iyer, Daryl E. Herzmann, Erik A. Endacott

Agronomy Publications

The Soil Moisture and Ocean Salinity (SMOS) remote sensing satellite was launched by the European Space Agency in 2009. The L-band brightness temperature observed by SMOS has been used to produce estimates of both soil moisture and τ, the optical thickness of the land surface. Although τ should theoretically be proportional to the amount of vegetation present within a SMOS pixel, several initial investigations have not been able to confirm this expected behavior. However, when the noise in the SMOS τ product is removed, τ in the U.S. Corn Belt, a region of extensive row-crop agriculture, has a distinct ...


Virus-Induced Gene Silencing And Transient Gene Expression In Soybean (Glycine Max) Using Bean Pod Mottle Virus Infectious Clones, Steven A. Whitham, Lori M. Lincoln, R. V. Chowda-Reddy, Jaime D. Dittman, Jamie A. O'Rourke, Michelle A. Graham Jun 2016

Virus-Induced Gene Silencing And Transient Gene Expression In Soybean (Glycine Max) Using Bean Pod Mottle Virus Infectious Clones, Steven A. Whitham, Lori M. Lincoln, R. V. Chowda-Reddy, Jaime D. Dittman, Jamie A. O'Rourke, Michelle A. Graham

Plant Pathology and Microbiology Publications

Virus-induced gene silencing (VIGS) is a powerful and rapid approach for determining the functions of plant genes. The basis of VIGS is that a viral genome is engineered so that it can carry fragments of plant genes, typically in the 200 to 300 base pair size range. The recombinant viruses are used to infect experimental plants, and wherever the virus invades, the target gene or genes will be silenced. VIGS is thus transient, and in the span of a few weeks, it is possible to design VIGS constructs and then generate loss-of-function phenotypes through RNA silencing of the target genes ...


The Effect Of Fungicides And Pod Removal Alone Or In Combination On Green Stem Disorder Of Soybean And Further Investigation Of Genetic Components, Xavier Phillips Jan 2016

The Effect Of Fungicides And Pod Removal Alone Or In Combination On Green Stem Disorder Of Soybean And Further Investigation Of Genetic Components, Xavier Phillips

Graduate Theses and Dissertations

Green stem disorder (GSD) of soybean (Glycine max L. Merr.) is when stems remain green and fleshy after pods reach physiological maturity and are ready to harvest. Little is known about GSD and its causes. Although GSD has not been shown to directly impact yield, the immature green stems may lead to harvest issues. Harvesting at the right time is essential to preserve the quality of the seed. During 2014 and 2015, field experiments located in central Iowa were used to investigate the effect of fungicides, pod removal, and their interaction on GSD incidence. The objective of this research was ...


Microscopic Characterization Of A Transposon-Induced Male-Sterile, Female-Sterile Mutant In Glycine Max L., Katherine A. Thilges Jan 2016

Microscopic Characterization Of A Transposon-Induced Male-Sterile, Female-Sterile Mutant In Glycine Max L., Katherine A. Thilges

Graduate Theses and Dissertations

A male-sterile, female-sterile mutant was identified in a transposon-tagging study in soybean (Glycine max L.). This mutant displayed abnormalities in both micro- and mega-sporogenesis, as well as gametogenesis. Vegetatively, the mutant showed no visible differences from the wild-type phenotype. Analyses of male meiotic chromosomes were done to better understand any issues that could occur to cause sterility. Wild-type and mutant anthers and ovules were cleared throughout their development, followed by confocal scanning laser microscopy to look for any abnormalities, and to determine the timing of abortion in both the male and female organs in the mutant. Additionally, scanning electron microscopy ...


Microscopic Characterization Of A Transposon-Induced Male-Sterile, Female-Sterile Mutant In Glycine Max L., Katherine A. Thilges Jan 2016

Microscopic Characterization Of A Transposon-Induced Male-Sterile, Female-Sterile Mutant In Glycine Max L., Katherine A. Thilges

Graduate Theses and Dissertations

A male-sterile, female-sterile mutant was identified in a transposon-tagging study in soybean (Glycine max L.). This mutant displayed abnormalities in both micro- and mega-sporogenesis, as well as gametogenesis. Vegetatively, the mutant showed no visible differences from the wild-type phenotype. Analyses of male meiotic chromosomes were done to better understand any issues that could occur to cause sterility. Wild-type and mutant anthers and ovules were cleared throughout their development, followed by confocal scanning laser microscopy to look for any abnormalities, and to determine the timing of abortion in both the male and female organs in the mutant. Additionally, scanning electron microscopy ...


Molecular Characterization Of Short And Long Term Iron Stress Responses In Soybean, Leorrie Ann Atencio Jan 2016

Molecular Characterization Of Short And Long Term Iron Stress Responses In Soybean, Leorrie Ann Atencio

Graduate Theses and Dissertations

Iron Deficiency Chlorosis (IDC) is a disease caused by lack of useable iron in the soil. Symptoms include stunting and interveinal chlorosis of the leaves, eventually leading to yield loss at the end of the season. IDC is particularly important in the upper Midwestern United States because soil conditions favor its development. With the use of next generation sequencing approaches, we characterized soybeans’ short and long-term response to iron stress. Our research takes advantage of two near isogenic lines that are 98% genetically identical but differ in their iron efficiency response. Clark plants are iron efficient, while Isoclark plants are ...


Soybean Vein Necrosis Virus: Impacts Of Infection On Yield Loss And Seed Quality And Expansion Of Plant Host Range, Melissa Irizarry Jan 2016

Soybean Vein Necrosis Virus: Impacts Of Infection On Yield Loss And Seed Quality And Expansion Of Plant Host Range, Melissa Irizarry

Graduate Theses and Dissertations

Soybean vein necrosis virus (SVNV) rapidly became a widespread soybean (Glycine max) virus within a few years of its initial confirmation in 2008. The economic impact of soybean vein necrosis (SVN) disease remains unknown. Soybean is a crop of global importance with nearly 4 billion bushels of soybeans produced in the United States in 2014. This study was designed to pursue two main questions; is there any yield loss or change in seed quality associated with SVN and are there horticultural or cover crop species that could be serving as sources of SVNV inoculum?

In order to determine if there ...


Rye Cover Crop Biomass, Nutrient Composition And Crop Management Practices To Enhance Corn Yield, Swetabh Patel Jan 2016

Rye Cover Crop Biomass, Nutrient Composition And Crop Management Practices To Enhance Corn Yield, Swetabh Patel

Graduate Theses and Dissertations

Winter cereal rye (Secale cereal L.), a commonly used cover crop in corn (Zea mays L.) systems has potential to scavenge soil NO3–N through a fibrous root system. The objective of this study was to quantify root and shoot biomass, C, and N partitioning in rye cover crop at the time of termination in spring. This was a one–year study conducted at a site with a no-till corn–soybean [Glycine max (L.) Merr.] rotation, rye drilled following grain crop harvest, and three N rates applied to corn (0, 135, and 225 kg N ha–1). Rye root biomass ...


Identification And Characterization Of Brown Stem Rot Resistance In Soybean, Chantal Elaine Mccabe Jan 2016

Identification And Characterization Of Brown Stem Rot Resistance In Soybean, Chantal Elaine Mccabe

Graduate Theses and Dissertations

Breeding for pathogen resistance is an important objective to improve and protect soybean yields. In 2010, 14.4% of total soybean yield was suppressed by diseases. Brown stem rot (BSR), caused by the fungus Phialophora gregata, reduces yield by as much as 38%. To date, three dominant BSR resistance genes have been identified: Rbs1, Rbs2, and Rbs3. The objectives of my research were 1) to determine if plant introductions contained novel BSR resistance genes, 2) to determine the correlation between P. gregata hyphae growth and foliar symptoms as well as characterize the response of the three BSR resistance genes to ...


Studies On Cover Crops And Sudden Death Syndrome Of Soybean, Renan Kobayashi-Leonel Jan 2016

Studies On Cover Crops And Sudden Death Syndrome Of Soybean, Renan Kobayashi-Leonel

Graduate Theses and Dissertations

Soybean sudden death syndrome (SDS), caused by Fusarium virguliforme, is a major soybean disease affecting soybean production in the United States. In search for more diversified cropping systems, the adoption of cover crops in the corn-soybean rotation is being encouraged. However, there is lack of information regarding the impact that cover cropping can have on SDS. On the one hand, it is possible that the improvements in soil health caused by cover crop can create an environment that is not favorable to the disease. On the other hand, F. virguliforme is able to colonize many plant species and, if a ...


Genome-Wide Association And Epistasis Studies Of Sclerotinia Sclerotiorum Resistance In Soybean, Tara Catherine Moellers Jan 2016

Genome-Wide Association And Epistasis Studies Of Sclerotinia Sclerotiorum Resistance In Soybean, Tara Catherine Moellers

Graduate Theses and Dissertations

Sclerotinia stem rot or white mold (WM) [Sclerotinia sclerotiorum (Lib.) de Bary] is an important fungal disease affecting soybean [Glycine max (L.) Merr.] and causes yield and quality losses. WM is prevalent in cool and moist environments, particularly in the soybean growing regions of Northern United States and Canada. Although sources of complete resistance have not yet been identified, several quantitative trait loci (QTL) for partial resistance have been reported but generally using bi-parental mapping populations. Genome-wide association (GWA) studies have been used to dissect complex disease resistance traits in plants and to identify the genes controlling the expression. WM ...


Modeling Long-Term Corn Yield Response To Nitrogen Rate And Crop Rotation, Laila A. Puntel, John E. Sawyer, Daniel Barker, Ranae N. Dietzel, Hanna Poffenbarger, Michael J. Castellano, Kenneth J. Moore, Peter Thorburn, Sotirios Archontoulis Jan 2016

Modeling Long-Term Corn Yield Response To Nitrogen Rate And Crop Rotation, Laila A. Puntel, John E. Sawyer, Daniel Barker, Ranae N. Dietzel, Hanna Poffenbarger, Michael J. Castellano, Kenneth J. Moore, Peter Thorburn, Sotirios Archontoulis

Agronomy Publications

Improved prediction of optimal N fertilizer rates for corn (Zea mays L.) can reduce N losses and increase profits. We tested the ability of the Agricultural Production Systems sIMulator (APSIM) to simulate corn and soybean (Glycine max L.) yields, the economic optimum N rate (EONR) using a 16-year field-experiment dataset from central Iowa, USA that included two crop sequences (continuous corn and soybean-corn) and five N fertilizer rates (0, 67, 134, 201, and 268 kg N ha-1) applied to corn. Our objectives were to: (a) quantify model prediction accuracy before and after calibration, and report calibration steps; (b) compare ...


Candidate Perennial Bioenergy Grasses Have A Higher Albedo Than Annual Row Crops, Jesse N. Miller, Andy Vanloocke, Nuria Gomez-Casanovas, Carl J. Bernacchi Jan 2016

Candidate Perennial Bioenergy Grasses Have A Higher Albedo Than Annual Row Crops, Jesse N. Miller, Andy Vanloocke, Nuria Gomez-Casanovas, Carl J. Bernacchi

Agronomy Publications

The production of perennial cellulosic feedstocks for bioenergy presents the potential to diversify regional economies and the national energy supply, while also serving as climate ‘regulators’ due to a number of biogeochemical and biogeophysical differences relative to row crops. Numerous observational and model-based approaches have investigated biogeochemical trade-offs, such as increased carbon sequestration and increased water use, associated with growing cellulosic feedstocks. A less understood aspect is the biogeophysical changes associated with the difference in albedo (a), which could alter the local energy balance and cause local to regional cooling several times larger than that associated with offsetting carbon. Here ...


Reduced Fitness Of Virulent Aphis Glycines (Hemiptera: Aphididae) Biotypes May Influence The Longevity Of Resistance Genes In Soybean, Adam J. Varenhorst, Michael T. Mccarville, Matthew E. O'Neal Sep 2015

Reduced Fitness Of Virulent Aphis Glycines (Hemiptera: Aphididae) Biotypes May Influence The Longevity Of Resistance Genes In Soybean, Adam J. Varenhorst, Michael T. Mccarville, Matthew E. O'Neal

Entomology Publications

Sustainable use of insect resistance in crops require insect resistance management plans that may include a refuge to limit the spread of virulence to this resistance. However, without a loss of fitness associated with virulence, a refuge may not prevent virulence from becoming fixed within a population of parthenogenetically reproducing insects like aphids. Aphid-resistance in soybeans (i.e., Rag genes) prevent outbreaks of soybean aphid (Aphis glycines), yet four biotypes defined by their capacity to survive on aphid-resistant soybeans (e.g., biotype-2 survives on Rag1 soybean) are found in North America. Although fitness costs are reported for biotype-3 on aphid ...


Survey Of Soybean Insect Pollinators: Community Identification And Sampling Method Analysis, K. A. Gill, M. E. O'Neal Jun 2015

Survey Of Soybean Insect Pollinators: Community Identification And Sampling Method Analysis, K. A. Gill, M. E. O'Neal

Entomology Publications

Soybean, Glycine max (L.) Merrill, flowers can be a source of nectar and pollen for honey bees, Apis mellifera L. (Hymenoptera: Apidae), wild social and solitary bees (Hymenoptera: Apoidea), and flower-visiting flies (Diptera). Our objectives were to describe the pollinator community in soybean fields, determine which sampling method is most appropriate for characterizing their abundance and diversity, and gain insight into which pollinator taxa may contact soybean pollen. We compared modified pan traps (i.e., bee bowls), yellow sticky traps, and sweep nets for trapping pollinators in Iowa soybean fields when soybeans were blooming (i.e., reproductive stages R1–R6 ...


Evaluation Of Spontaneous Generation Of Allelic Variation In Soybean In Response To Sexual Hybridization And Stress, Katherine Espinosa, Jessica Boelter, Susan Lolle, Marianne Hopkins, Susana Goggi, Reid G. Palmer, Devinder Sandhu Mar 2015

Evaluation Of Spontaneous Generation Of Allelic Variation In Soybean In Response To Sexual Hybridization And Stress, Katherine Espinosa, Jessica Boelter, Susan Lolle, Marianne Hopkins, Susana Goggi, Reid G. Palmer, Devinder Sandhu

Agronomy Publications

Intra-cultivar variation reported in pure lines of soybean has been hypothesized to result from genetic mechanisms contributing to de novo genetic variation. In this study we have detected allele switching by following segregation pattern of Aconitase-4 isozyme in sexual crosses and pure lines. In sexual crosses, one F2 plant showed switch at the Aconitase- 4 (Aco4) locus from the expected heterozygous genotype Aco4-ac to Aco4-ab. In the pure lines grown in a honeycomb planting design and treated with an accelerated aging test, multiple cases of allele switching were detected at the Aco4 locus. Both single and double switches were detected ...


Influence Of Bradyrhizobium Inoculation And Fungicide Treatment On Development And Yield Of Selected Pulse Crops; Nutritional Composition Of Pulse Legume Leaves And The Impact Of Leaf Removal On Yield, Rosemary Bulyaba Jan 2015

Influence Of Bradyrhizobium Inoculation And Fungicide Treatment On Development And Yield Of Selected Pulse Crops; Nutritional Composition Of Pulse Legume Leaves And The Impact Of Leaf Removal On Yield, Rosemary Bulyaba

Graduate Theses and Dissertations

Part 1

Declining soil fertility due to inadequate nitrogen in most soils limits farmers’ goals of increasing yield. There is environmental and agricultural benefit of reducing dependence on nitrogen fertilizer by emphasizing adaptation of favorable farming practices that minimize nitrogen fertilizer. Cowpea [Vigna unguiculata (L.) Walp.] and lablab (Lablab purpureus (L.)] are pulses with potential for grain, forage, and cover crops in the Midwest of United States, but little is known about their growth, development, and productivity potential in Iowa. We conducted a two-year field study to determine the influence of rhizobia inoculation and fungicide seed treatment of selected pulses ...


Local Vs. Systemic Modifications Of Soybean (Glycine Max) Defense Signals In Response To Soybean Aphid (Aphis Glycines Matsumura) Infestation, Khoi Nguyen Jan 2015

Local Vs. Systemic Modifications Of Soybean (Glycine Max) Defense Signals In Response To Soybean Aphid (Aphis Glycines Matsumura) Infestation, Khoi Nguyen

Graduate Theses and Dissertations

Soybean aphids, Aphis glycines, are a specialized phloem-feeding pest of soybeans. They are known to employ different mechanisms to bypass plant defenses and reduce soybean plant yields of up to 50% a year. Once attacked or sensing distress, soybeans induce the oxylipin pathway, a biosynthetic pathway that produces key plant hormones. Among these hormones is jasmonic acid (JA), which is produced from linolenic acid (18:3). Jasmonic acid can signal the production of protease inhibitors as one of the products that obstructs the attackers’ ability to digest protein. Previous studies show that levels of three key fatty acid precursors (palmitic ...


Plant Tissue Analysis To Assess Phosphorus And Potassium Nutritional Status Of Corn And Soybean In Iowa, Andrew John Stammer Jan 2015

Plant Tissue Analysis To Assess Phosphorus And Potassium Nutritional Status Of Corn And Soybean In Iowa, Andrew John Stammer

Graduate Theses and Dissertations

Interest in re-evaluating the value of tissue testing to assess P and K status in corn (Zea mays L.) and soybean (Glycine max L. Merr.) is increasing. The objective of this research was to study relationships between grain yield response to P and K and the concentration of these nutrients in plant tissue. Single-year and multi-year response trials were conducted in Iowa at 30 sites for P (32 sites-years with corn and 34 with soybean) and at 53 for K (67 sites years with corn and 52 with soybean) that encompassed 17 soil series. We sampled above-ground plant parts at ...


Phenotypic And Genetic Variation In An Apios Americana Breeding Collection; And Characterization Of The Hd-Zip Gene Family, Involved In Abiotic Stress Responses In Glycine Max, Vikas Belamkar Jan 2015

Phenotypic And Genetic Variation In An Apios Americana Breeding Collection; And Characterization Of The Hd-Zip Gene Family, Involved In Abiotic Stress Responses In Glycine Max, Vikas Belamkar

Graduate Theses and Dissertations

This dissertation has two main objectives: (1) morphological and genetic characterization of a little-studied edible legume native to North America, Apios americana; and (2) characterization of the soybean (Glycine max) homeodomain leucine zipper (HD-Zip) transcription factor family (involved in abiotic stress responses), and identification of candidate genes for dehydration and salt stress. In these projects, next generation sequencing (NGS) is evaluated as a tool for rapidly characterizing genetic variation (in Apios) and fine-scale genetic responses to abiotic stress (in soybean).

Apios, commonly called “potato bean,” is a nitrogen-fixing legume that is adapted to diverse climatic conditions of central and eastern ...


Aboveground Feeding By Soybean Aphid, Aphis Glycines, Affects Soybean Cyst Nematode, Heterodera Glycines, Reproduction Belowground, Michael T. Mccarville, David H. Soh, Gregory L. Tylka, Matthew E. O'Neal Jan 2014

Aboveground Feeding By Soybean Aphid, Aphis Glycines, Affects Soybean Cyst Nematode, Heterodera Glycines, Reproduction Belowground, Michael T. Mccarville, David H. Soh, Gregory L. Tylka, Matthew E. O'Neal

Entomology Publications

Heterodera glycines is a cyst nematode that causes significant lost soybean yield in the U.S. Recent studies observed the aphid Aphis glycines and H. glycines interacting via their shared host, soybean, Glycine max. A greenhouse experiment was conducted to discern the effect ofA. glycines feeding on H. glycines reproduction. An H. glycines-susceptible cultivar, Kenwood 94, and a resistant cultivar, Dekalb 27–52, were grown in H. glycines-infested soil for 30 and 60 d. Ten days after planting, plants were infested with either zero, five, or ten aphids. At 30 and 60 d, the number of H ...