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Iowa State University

Soybean

Plant Sciences

Graduate Theses and Dissertations

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Utilization Of Near-Isogenic Lines To Identify Genes Underlying Iron-Efficiency Qtl, Gregory Allan Peiffer Jan 2011

Utilization Of Near-Isogenic Lines To Identify Genes Underlying Iron-Efficiency Qtl, Gregory Allan Peiffer

Graduate Theses and Dissertations

Nutrient deficiencies are a significant abiotic stress of soybean. Iron deficiency chlorosis is a major concern in the upper midwestern region of the United States due to the prevalence of calcareous soils. Soybean's susceptibility to iron stress results in yield losses into the hundreds of millions each year. Understanding the molecular differences between resistant and susceptible cultivars will significantly affect future yield and revenue. Through the use of near-isogenic lines (NILs), molecular markers, and gene expression we have identified the donor parent introgressions through both classical SSR mapping and a novel method of SNP clustering which can be preformed ...


Effects Of Phosphorus And Potassium Fertilization Rate And Placement Method On Soybean (Glycine Max L.) Seed Quality And Long-Term Storability, Keaton Krueger Jan 2011

Effects Of Phosphorus And Potassium Fertilization Rate And Placement Method On Soybean (Glycine Max L.) Seed Quality And Long-Term Storability, Keaton Krueger

Graduate Theses and Dissertations

The fertilization rate and placement methods of phosphorus and potassium fertilizers can positively affect soybean [Glycine max L. (Merr.)] seed composition and yield in some environments, but not in others. Soybean seed production costs and chemically-treated seed disposal costs have increased, coinciding with farmers' adoption of planting chemically-treated soybean seeds. Seeds are treated with fungicides and sometimes with insecticides to provide protection from pathogens and insects before seed emergence. These changes in production costs have renewed seed industry's interest in identifying agronomic practices that enhance soybean quality, composition, and storability. Soybean seeds do not store well and seed quality ...


Replication Protein A And Its Role In The Iron Stress Response Of Soybean, Sarah Atwood Jan 2011

Replication Protein A And Its Role In The Iron Stress Response Of Soybean, Sarah Atwood

Graduate Theses and Dissertations

Soybean (Glycine max (L.) Merr.) is the second most abundant crop in the United States, with a total crop value of nearly $39 billion in 2010. U.S. soybean exports are used as an important protein and oil source in over 80 countries. Abiotic stress, such as iron deficiency chlorosis (IDC), threatens soybean yields, which affect farmers' profits in the United States as well as nutrition of consumers all over the world. IDC occurs when iron is unavailable to soybean roots, often in the calcareous soils of the upper Midwest United States. Iron stress causes a decrease in chlorophyll production ...


Environmental Analyses And Candidate Gene Expression Of Ms9 Male-Sterility Locus And Computational Identification Of Candidate Genes For Male-Sterility Loci In Soybean, Christiana Wiebbecke Jan 2011

Environmental Analyses And Candidate Gene Expression Of Ms9 Male-Sterility Locus And Computational Identification Of Candidate Genes For Male-Sterility Loci In Soybean, Christiana Wiebbecke

Graduate Theses and Dissertations

Rapid growth rate of the human population is driving the increased demand for cultivated soybean [Glycine max (L.) Merrill], a major source of protein and oil in global food, feed, and biofuel production. Increasing yield at a pace faster than traditional breeding methods presently achieve has become a need and future commitment. In soybean, a self-pollinated crop, a possibility to increase yield may result from the development of hybrid cultivars. Researchers have been interested in floral development and pollination, as these factors have a direct impact on maintaining and enhancing crop yields. Soybean breeders also need to understand phenotypic differences ...


Epidemiological Studies On The Infection Process And Symptom Expression Of Soybean Sudden Death Syndrome, Carlos Cecilio Gongora-Canul Jan 2010

Epidemiological Studies On The Infection Process And Symptom Expression Of Soybean Sudden Death Syndrome, Carlos Cecilio Gongora-Canul

Graduate Theses and Dissertations

Sudden death syndrome (SDS) caused by Fusarium virguliforme (Aoki, O'Donnel, Homma & Lattanzi) is one of the most important soybean (Glycine max (L.) Merr.) diseases in the US. Management strategies currently available for this disease are not always effective, partly due to the high variability in symptom expression that occurs in field environments. To clarify the relationship between progress of root rot and foliar symptoms, soybean seedlings were inoculated at five inoculum densities and were destructively sampled over a 50 day period. Disease severity and area under disease progress curve (AUDPC) increased in response to increasing inoculum density (P < 0.01), particularly for foliar symptoms. Root rot severity evaluated 15 to 31 days after inoculation (DAI) was most highly correlated (r ...


Agronomic And Seed Traits Of Soybean Lines With The Rag1 Gene For Aphid Resistance, Justin Lee Mardorf Jan 2010

Agronomic And Seed Traits Of Soybean Lines With The Rag1 Gene For Aphid Resistance, Justin Lee Mardorf

Graduate Theses and Dissertations

Soybean [Glycine max (L.) Merrill] yields can be reduced significantly by infestations of the soybean aphid (Aphis glycines Matsumura). A dominant allele, Rag1, providing resistance to the aphid was identified in PI 548663. The objective of this study was to compare the agronomic and seed traits of 27 BC2F2-derived lines with the Rag1 allele to those of 27 lines with the rag1 allele from the same segregating population. The lines were evaluated under aphid-infested conditions at two Iowa environments in 2008 and under aphid-infested and aphid-free conditions at three Iowa environments during 2009. There were significant differences in mean yield ...


Tillage Effects On Soybean Growth, Development, And Yield, Alecia Marie Kiszonas Jan 2010

Tillage Effects On Soybean Growth, Development, And Yield, Alecia Marie Kiszonas

Graduate Theses and Dissertations

Profit margins of soybean [Glycine max (L.) Merr.] in the United States have recently declined as a result of an increase in production and land costs. Decreased profits coupled with increasing environmental concerns such as erosion and runoff prompts more cost-efficient production practices. No-tillage production practices offer a lower cost of production in addition to decreased soil erosion and runoff. Additionally, soil quality can be improved over time in a no-tillage system, greatly increasing the yield benefits over time. Today, only 41% of Iowa's soybean production is under no-tillage production (Conservation Technology Information Center, 2010), although even more of ...


Genomic Analysis Of A Major Seed Protein/Oil Qtl Region On Soybean Linkage Group I, Bindu Joseph Jan 2009

Genomic Analysis Of A Major Seed Protein/Oil Qtl Region On Soybean Linkage Group I, Bindu Joseph

Graduate Theses and Dissertations

The economic and nutritional value of soybeans is determined by its seed protein and oil contents. The genetic control of seed protein/oil is quantitative and many genomic regions associated with the regulation of these traits have been identified in soybean. The protein/oil quantitative trait locus (QTL) mapped to LG I (chromosome 20) is ubiquitous among high protein soybean lines. Identification of the candidate gene(s) underlying this major QTL would help us understand the genetic and molecular mechanisms regulating seed protein/oil accumulation in soybean. Map based cloning to identify the candidate genes for the LG I QTL ...


Agronomic, Seed Composition And Molecular Characteristics Of Soybean Lines With Novel Genes For Modified Glycinin And Beta-Conglycinin Content, Jonathan Jenkinson Jan 2009

Agronomic, Seed Composition And Molecular Characteristics Of Soybean Lines With Novel Genes For Modified Glycinin And Beta-Conglycinin Content, Jonathan Jenkinson

Graduate Theses and Dissertations

Soybean [Glycine max (L.) Merr.] genotypes with increased beta-conglycinin (BC) and reduced glycinin (Gly) may be beneficial to food product quality and to human health. A soybean line, B2G2, developed in Japan, has the recessive alleles gy1, gy2, gy3, gy4, and gy5 that control Gly content. Its seed protein has about 50 g kg-1 BC and 0 g kg-1 Gly. Monsanto Co. has used B2G2 to develop lines with different combinations of recessive and wild-type alleles at the five Gy loci. The first objective of this research was to determine the influence of different combinations of the gy and Gy ...


Genetic Improvement Of Seedling Emergence Of Low-Phytate Soybean Lines, Loren Ambrose Trimble Jan 2009

Genetic Improvement Of Seedling Emergence Of Low-Phytate Soybean Lines, Loren Ambrose Trimble

Graduate Theses and Dissertations

Reduced seedling emergence of low-phytate (LP) soybean [Glycine max (L.) Merr.] lines with the pha1 and pha2 alleles has been a limiting factor in the development of LP cultivars. Crosses between normal-phytate (NP) and LP soybean lines have produced progeny with improved emergence. The objective of this study was to determine if LP lines with improved emergence are capable of producing progeny with equal or higher emergence when crossed to NP parents. LP lines with improved emergence were crossed to NP cultivars and the LP progeny were evaluated with seed produced at three 2007 locations and five 2008 locations. A ...


Cyst Nematode Resistance And Seed Yield Of Soybean Lines Derived From Ss97-6946, Gregory Lynn Doonan Jan 2009

Cyst Nematode Resistance And Seed Yield Of Soybean Lines Derived From Ss97-6946, Gregory Lynn Doonan

Graduate Theses and Dissertations

New sources of resistance to the soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) would be useful for soybean [Glycine max (L.) Merr.] cultivar development. The objective of this study was to determine the relationship between SCN resistance and seed yield for a new source of SCN resistance, SS97-6946, developed by the Univ. of Missouri-Columbia. F5-derived lines were developed from the cross of SS97-6946 x S27-T7, a SCN-susceptible cultivar developed by Syngenta. Nine sets of 32 F5:8 lines each were evaluated for yield in replicated tests at five Midwest locations during 2007. The lines were evaluated for resistance to four ...


Use Of Seed Treatments And Inoculants In No-Tillage Soybean Production Practices, Joseph John Osenga Jan 2009

Use Of Seed Treatments And Inoculants In No-Tillage Soybean Production Practices, Joseph John Osenga

Graduate Theses and Dissertations

Soybean producers using no-tillage practices in the Upper Midwest encounter cooler, wetter soil conditions early in the growing season that slow crop growth and favor damping-off pathogens. The goal of this thesis work was to evaluate the use of soybean seed treatments and inoculants in no-tillage compared to conventional tillage practices in Iowa. The research reported in this thesis is divided into three specific objectives. The first objective was to evaluate the use of soybean seed treatments and inoculants in no-tillage and conventional tillage across Iowa. It was concluded that there was no evidence that the use of seed treatments ...


Soil And Fertilizer Potassium Impacts On Corn And Soybean Grain Yield, Potassium Uptake, And Within-Field Grain Yield Variation, Matthew William Clover Jan 2008

Soil And Fertilizer Potassium Impacts On Corn And Soybean Grain Yield, Potassium Uptake, And Within-Field Grain Yield Variation, Matthew William Clover

Graduate Theses and Dissertations

Two studies were conducted in Iowa to better understand how potassium (K) fertilization affects grain yield, vegetative growth, and K concentration of different parts of modern corn (Zea mays L.) hybrids and soybean (Glycine max L. Merr.) varieties. One study was based on one- to three-year strip-trials (63 site-years) conducted from 2001 to 2007 to evaluate the effects of K fertilization on corn and soybean grain yield and post-harvest soil-test K (STK) measured with the ammonium acetate extractant. Replicated treatments were 0 and 168 kg K ha-1. Potassium increased yield as evaluated by strip averages in 21 of 63 ...