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Management Strategies To Improve Soybean Yield In High Ph Soybean Cyst Nematode Infested Fields , Vladimir Azevedo Da Costa Jan 2006

Management Strategies To Improve Soybean Yield In High Ph Soybean Cyst Nematode Infested Fields , Vladimir Azevedo Da Costa

Retrospective Theses and Dissertations

Soybean cyst nematode (Heterodera glycines; SCN) causes the greatest yield losses of all diseases on soybean [Glycine max (L.) Merr.] in Iowa. Growing SCN-resistant varieties in rotation with non-host crops and SCN-susceptible varieties is the current management recommendation for SCN in Iowa. Previous research has shown that SCN population densities are positively correlated with soil pH. The correlation may reduce the efficacy of the current SCN management recommendation in northern and central Iowa, which is located in the Des Moines lobe area, a calcareous soil area with high pH soil. The hypothesis for this research is that additional management strategies ...


Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong Jan 2006

Function Of Autophagy In Development And Abiotic Stress Tolerance In Arabidopsis Thaliana , Yan Xiong

Retrospective Theses and Dissertations

Autophagy is a process in which cytoplasmic components are degraded in the vacuole. It occurs when organisms are subjected to environmental stress conditions or during certain stages of development. Upon induction of autophagy, a portion of cytoplasm is surrounded by a double membrane structure to form an autophagosome. The outer membrane of the autophagosome then fuses with the vacuole and the inner membrane and its contents are degraded by vacuolar hydrolases. The morphological characteristics of autophagy have been observed in plants for decades and several autophagy defective mutants have been isolated recently; however, little is known about the molecular mechanism ...


Phenotypic, Biochemical, And Molecular Diversity In Coriander (Coriandrum Sativum L) Germplasm, Pedro Antonio López Jan 2006

Phenotypic, Biochemical, And Molecular Diversity In Coriander (Coriandrum Sativum L) Germplasm, Pedro Antonio López

Retrospective Theses and Dissertations

A study was conducted to assess phenotypic, biochemical, and molecular diversity in coriander accessions from the North Central Regional Plant Introduction Station, in Ames, IA; initially, 139 accessions were characterized for phenological and morphological traits and for fatty-acid composition. A second year of data was collected on those traits from 60 accessions. Fruit essential-oil content and composition were determined, along with a headspace analysis from leaves and an analysis of amplified fragment length polymorphisms (AFLPs). Basic statistics and Pearson correlations were estimated. Matrices of geographical distances (GD), modified Rogers' (MD) distances for molecular data, and Euclidean distances for phenotypic (PD ...


Management Of Grape Colaspis, Colaspis Brunnea (Coleoptera: Chrysomelidae), In Seed Corn Production , Benjamin Carl Kaeb Jan 2006

Management Of Grape Colaspis, Colaspis Brunnea (Coleoptera: Chrysomelidae), In Seed Corn Production , Benjamin Carl Kaeb

Retrospective Theses and Dissertations

In recent years, grape colaspis, Colaspis brunnea (F.), larvae have caused significant injury to seed corn by feeding on the surface of the root, denuding it of root hairs. This study tested two management techniques for C. brunnea in seed corn. The first objective was to test the efficacy of commercially available insecticides, specifically neonicotinoid seed treatments, in protecting commercial seed corn from C. brunnea larval injury. The results of this study showed insecticides offer protection to the seedling corn from C. brunnea larvae; however, no insecticide treatment significantly outperformed any other. The second objective was to develop and test ...


Integration Of Remote Sensing And Crop Growth Modeling For Nitrogen Management Decision Support In Corn , Kelly Robert Thorp Jan 2006

Integration Of Remote Sensing And Crop Growth Modeling For Nitrogen Management Decision Support In Corn , Kelly Robert Thorp

Retrospective Theses and Dissertations

This dissertation describes efforts to move toward a completely integrated remote sensing and crop growth modeling tool for developing precision nitrogen management recommendations for corn. Aerial hyperspectral remote sensing imagery collected throughout the 2004 growing season was used to estimate corn plant stand density, and a machine vision system was used to map corn population on the ground. Multiple linear regression analysis was used to assess the ability of all combinations of three reflectance bands to estimate corn plant population at resolutions of 2 m, 6 m, and 10 m. Coefficients of multiple determination of up to 0.82 were ...


Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez Jan 2006

Relationship Between Concentration Of Isoflavones In Soybean Grain And Potassium Fertilization , Mario Valadez Ramirez

Retrospective Theses and Dissertations

Soybean grain contains isoflavones that may prevent various human diseases. Previous studies in Canada found that K fertilization and high grain K concentration can result in increased isoflavones concentration in grain, but effects were inconsistent across sites and soil-test K (STK) levels. The objective of this study was to assess (1) effects of K fertilization on the concentration of isoflavones and K in soybean grain and (2) relationships between soybean grains K concentration, isoflavone concentration, and yield. The study was based on analyses of grain collected from selected treatments and years of six Iowa long-term experiments that investigated effects of ...


The Quantitative Genetics Of A Non-Stiff-Stalk Maize (Zea Mays L) Population , Brandon M. Wardyn Jan 2006

The Quantitative Genetics Of A Non-Stiff-Stalk Maize (Zea Mays L) Population , Brandon M. Wardyn

Retrospective Theses and Dissertations

The genetic relationship among individuals is at the core of nearly all quantitative genetic theory. Dominant gene action has long been either ignored or disregarded as insignificant in many previous genetic models. For grain yield in maize (Zea mays L.), dominance has consistently accounted for a large proportion of genetic variance. We have used previously developed genetic theory that accounts for dominance variance during inbreeding and applied it to a unique breeding design. Our breeding design allowed us to estimate five genetic covariance parameters for six traits. In addition, we developed genetic gain equations that accounted for both dominance and ...


Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska Jan 2006

Use Of Precision Agriculture Technologies In Studying The Relationships Among Soil Ph, Calcium Carbonate Equivalent, Soybean Cyst Nematode Population Density, And Soybean Yield , Natalia Rogovska

Retrospective Theses and Dissertations

Iron deficiency chlorosis (IDC) and soybean cyst nematode (SCN; Heterodera glycines) infestation are major factors that contribute to soybean (Glycine max Merr.) yield reduction in the Midwest. The IDC is often associated with soybean grown on high pH, calcareous soils. In addition, it was documented that SCN population density is higher in high pH soils. The objectives of this paper were to assess the proportion of within-field soybean yield and SCN variability that could be explained by soil pH, calcium carbonate equivalent (CCE), and a previously defined alkalinity stress index (ASI). Aerial images from 21 fields planted to SCN-resistant or ...


Effects Of Crop Rotation And Nitrogen Fertilization On Soil Nitrate Concentration And Corn Yield , Enrique Ortiz-Torres Jan 2006

Effects Of Crop Rotation And Nitrogen Fertilization On Soil Nitrate Concentration And Corn Yield , Enrique Ortiz-Torres

Retrospective Theses and Dissertations

Increasing concerns about production cost and environmental impacts of N fertilization require improving N management. The objectives of this study were to evaluate effects of cropping sequences and N fertilization on (1) corn yield and yield stability and (2) soil nitrate concentration in two Iowa long-term rotation experiments and (3) to assess the performance of the late spring nitrate test (LSNT) to assess N availability for corn in several cropping sequences. The experiments were near Kanawha (20 yrs) and Nashua (26 yrs) and N fertilization rates for corn were 0, 90, 180, 270 kg N ha -1. Rotations in Kanawha ...


Sampling And Management Of Aphidophagous Natural Enemies In Iowa Soybean , Nicholas Patrick Schmidt Jan 2006

Sampling And Management Of Aphidophagous Natural Enemies In Iowa Soybean , Nicholas Patrick Schmidt

Retrospective Theses and Dissertations

In Iowa, surveys of natural enemies in soybean [Glycine max (L.) Merr.] conducted before the arrival of Aphis glycines Matsumara (Hemiptera: Aphididae) revealed several species that may contribute to the mortality of A. glycines. In 2004 and 2005, several sampling methods were investigated to determine if diversity of the natural enemy community in Iowa soybean has changed with the arrival of A. glycines. We hypothesized that the natural enemy community in soybean has changed with the introduction of A. glycines and that sampling methods would collect different species of natural enemies. Also, with the use of an alfalfa living mulch ...


Genetic Improvement Of Seedling Emergence Of Soybean Lines With Low Phytate , Jordan Dustin Spear Jan 2006

Genetic Improvement Of Seedling Emergence Of Soybean Lines With Low Phytate , Jordan Dustin Spear

Retrospective Theses and Dissertations

Seedling emergence of low-phytate (LP) soybean [Glycine max (L.) Merr.] lines has been reported to be lower than that of normal-phytate (NP) lines. One objective of this study was to evaluate if backcrossing the LP trait into a NP line would result in LP progeny with normal emergence. The LP line CX1834-1-6 (CX1834) was crossed to B01769B019 (B019), a NP line with reduced palmitate content, and three backcrosses were made to B019. A total of 36 BC3F4-derived LP lines from the population were evaluated at five locations in 2005 in comparison with CX1834, B019, and a NP cultivar IA3023. The ...


Influence Of Soybean Population On The Efficacy Of Glyphosate , Guillermo D. Arce Reyes Jan 2006

Influence Of Soybean Population On The Efficacy Of Glyphosate , Guillermo D. Arce Reyes

Retrospective Theses and Dissertations

Studies were conducted at three Iowa locations in 2005 and 2006 to test if a reduction in soybean seeding rate would reduce weed suppression and increase glyphosate efficacy. The cultivar H-2162 RR was planted at four seeding rates (240,000, 300,000, 360,000, and 420,000 seed ha-1) for both experiments. In the first experiment, treatments included glyphosate applied at V2, V4, V6, and V2+V6 soybean stage at Boone, Hancock and Story. Weed control efficacy was influenced more by application timing than by soybean seeding rate, while grain yield was influenced more by soybean population than application timing ...


Vegetative Filter Strip Assessment In The State Of Iowa, Manveen Bansal Jan 2006

Vegetative Filter Strip Assessment In The State Of Iowa, Manveen Bansal

Retrospective Theses and Dissertations

Vegetative filter strips (VFS) is one of the best management practices that uses natural processes to remove a portion of the sediment and other pollutants carried by runoff before the water enters a water-body. The project analyzes the flow accumulation of runoff with the help of Geographic Information Systems (GIS). The objectives for this project include (1) To determine the effectiveness of VFS by visual field observation and validation by flow mapping procedures in ArcGIS 9, (2) To compare the area ratios and percentage of flow along each stream segment at various resolutions for different sizes of the survey data ...


Diversity And Efficacy Of Arbuscular Mycorrhizal (Am) Fungi Isolated From Soils Of Soybean Fields , Zahra Ifnou Troeh Jan 2006

Diversity And Efficacy Of Arbuscular Mycorrhizal (Am) Fungi Isolated From Soils Of Soybean Fields , Zahra Ifnou Troeh

Retrospective Theses and Dissertations

A field survey evaluated the population composition of AM fungal species in Clarion (a well drained fine-loamy, mixed, mesic Typic Hapludoll) and Webster (a poorly drained fine-loamy, mixed, mesic Typic Endoaquoll) soils of four Iowa soybean (Glycine max, L.) fields. Spores from six species of Glomus and from the genera Acaulospora, Gigaspora , and Paragomus were found in the original field soils. G. claroideum, G. etunicatum, G. mosseae, G. viscosum, and Paraglomus occultum-like spores were prevalent in both Clarion and Webster soils of all four fields. Minor species included G. geosporum and G. intraradices. Trap cultures led to detection of several ...


Molecular Genetic Analyses Of Oilseed Brassica Germplasm: Determination Of Life Forms And Germplasm Management Strategies By Using Microsatellite Markers And Flowering Locus-C (Flc1 And Flc3) Gene Sequences , Von Mark V. Cruz Jan 2006

Molecular Genetic Analyses Of Oilseed Brassica Germplasm: Determination Of Life Forms And Germplasm Management Strategies By Using Microsatellite Markers And Flowering Locus-C (Flc1 And Flc3) Gene Sequences , Von Mark V. Cruz

Retrospective Theses and Dissertations

Molecular markers were utilized in conjunction with phenological and morphological information, and statistical methods for diversity analyses to address plant genetic resource conservation issues. The objectives of this study have been categorized into two sets. The first set pertains to exploratory surveys of genetic variation using molecular markers and DNA sequences to determine if microsatellite markers or variation in two copies of the FLOWERING LOCUS C gene (FLC1 and FLC3) can be used in determining life forms of fifty representative accessions of Brassica napus. The second set of objectives addresses good genebank practices and includes: characterization of flowering time of ...


Evaluation Of Seven Stiff-Stalk And Five Non-Stiff-Stalk Corn Populations, Hybrids, And S1'S , Thomas Edward Scheffler Jan 2006

Evaluation Of Seven Stiff-Stalk And Five Non-Stiff-Stalk Corn Populations, Hybrids, And S1'S , Thomas Edward Scheffler

Retrospective Theses and Dissertations

Performance of corn (Zea mays L.) breeding programs is based on germplasm selection of breeding populations and the ability to recognize and utilize heterotic patterns. The objective of this research is to identify superior corn populations that could be useful germplasm sources in producing inbreds for hybrid corn production. Population hybrids were produced using seven Stiff-Stalk and five Non-Stiff-Stalk populations. The 35 F1 hybrids and the original 12 populations were evaluated in an S0 randomized complete block design experiment at five locations in Iowa during 2003 and 2004. Concurrently, each of the 35 hybrids and 12 populations were selfed and ...


A Quantitative Trait Response Evaluation To Selection In The Bs13(S) Maize (Zea Mays L.) Population , Clinton J. Turnbull Jan 2006

A Quantitative Trait Response Evaluation To Selection In The Bs13(S) Maize (Zea Mays L.) Population , Clinton J. Turnbull

Retrospective Theses and Dissertations

Seven cycles of half-sib recurrent selection were conducted in the BSSS maize population followed by ten cycles of S2 progeny recurrent selection. The population under S2 progeny recurrent selection is formally known as BS 13(S). The selection criteria have always placed importance on high grain yield, low grain moisture, and reduced plant lodging. Two evaluations estimating the response of multiple agronomic traits in multiple response units including the population sampled at F IS = 0, FIS = 0.5, and FIS = 0.75 levels of inbreeding, and multiple testcrosses of the population were conducted. The average response of grain yield in ...


Soil Quality Response To Manure Or Compost Amendments In Alternative Iowa Farm Systems , Kevin Frederick Jensen Jan 2006

Soil Quality Response To Manure Or Compost Amendments In Alternative Iowa Farm Systems , Kevin Frederick Jensen

Retrospective Theses and Dissertations

This study was conducted to improve understanding of carbon (C) and nitrogen (N) cycling in alternative agricultural systems. In order to generate information that is directly applicable to farm contexts, the study was conducted in farmer fields. The focus of this study was the soil phase of the C and N cycle, where physical and biological processes transform C and N. However, the design of the study, featuring on-farm research in partnership with farmers, ensured that soil and plant performance factors were integrated with the practical logistics and judgment calls that are exercised by farmers.


Evaluation Of Potassium Soil Tests And Methods For Mapping Soil Fertility Properties In Iowa Corn And Soybean Fields , Pedro Aníbal Barbagelata Jan 2006

Evaluation Of Potassium Soil Tests And Methods For Mapping Soil Fertility Properties In Iowa Corn And Soybean Fields , Pedro Aníbal Barbagelata

Retrospective Theses and Dissertations

Improving the use of soil testing in production agriculture may result in increased nutrient use efficiency and profitability. Three studies were conducted in Iowa with this general goal. One study assessed the impact of soil sample drying on K extraction and developed field correlations of an ammonium-acetate K test (AA) based on field-moist samples for corn and soybean. Potassium extracted with AA from dried samples was higher than K extracted from moist samples. The difference increased with increasing drying temperature, was inversely related to the soil K level, and varied among soil series. The moist AA test correlated better with ...


Methods For Identifying Frost Injury In Immature Maize Seed , Mindy L. Devries Jan 2006

Methods For Identifying Frost Injury In Immature Maize Seed , Mindy L. Devries

Retrospective Theses and Dissertations

Fall frost damage is a major threat to maize (Zea mays L.) seed production in the central United States. Frost events prior to harvest can cause various physical, mechanical, biochemical, and physiological changes to immature seed corn. These changes can lead to decreased germination and vigor. Early detection of frost damage could reduce the financial loss caused by poor emergence when these seed lots are planted. The central hypotheses of this dissertation are that the severity of a frost event can be quantified shortly after seed has been harvested and dried, and that the magnitude of the damage is associated ...