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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

Corn

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Uhf Band Attenuation Through A Corn Canopy With Crop Growth, Richard Jay Cirone Jan 2019

Uhf Band Attenuation Through A Corn Canopy With Crop Growth, Richard Jay Cirone

Graduate Theses and Dissertations

Soil moisture and vegetation remote sensing measurements can be inaccurate and/or misinterpreted in the US Corn Belt, specifically when considering seasonal variation in standing vegetation. A direct crop water measurement method was employed to assist in correction of satellite measurements, specifically to SMOS and SMAP. A 433 MHz radio link was installed in a central Iowa cornfield, shortly after planting, across a distance of 50 meters, for the purpose of measuring attenuation by crop water. This experiment ran until mid grain fill, development stage R3. Vegetation water column density increased from essentially 0 at planting to just above 4 ...


A Statistical Analysis Of Zea Mays Grain Yield Response To Nitrification-Inhibitor Amendments Under Field Conditions Utilizing Parametric And Non-Parametric Techniques, Elliot H. Sully Jan 2019

A Statistical Analysis Of Zea Mays Grain Yield Response To Nitrification-Inhibitor Amendments Under Field Conditions Utilizing Parametric And Non-Parametric Techniques, Elliot H. Sully

Graduate Theses and Dissertations

Nitrification is a matter of economic and ecological importance in nitrogen-tensive agricultural practices such as corn (Zea mays) grain production. When ammonium is bacterially oxidized into nitrate it becomes more susceptible to leaching and denitrification as nitrous oxide. The nitrification process not only adds to water and air pollution but also impacts on farm productivity by reducing grains yields and increasing fertilizer demands. Nitrification inhibiting fertilizer amendments can potentially improve grain yields by retarding the growth of nitrifying soil bacteria. Multiple field studies conducted across various locations and timespans have generated mixed results regarding the grain yield difference attributed to ...


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

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

Graduate Theses and Dissertations

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

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


Nitrogen Pools And Fluxes In Diversified Cropping Systems, William Robert Osterholz Jan 2016

Nitrogen Pools And Fluxes In Diversified Cropping Systems, William Robert Osterholz

Graduate Theses and Dissertations

Achieving high crop yields requires a large supply of plant available nitrogen (N), yet losses of inorganic N from agriculture are deleterious to environmental quality. A significant portion of agricultural N losses could be prevented if large soil inorganic N pools were not needed to satisfy crop N demand. Alternative N management strategies that consider N fluxes like gross N mineralization in addition to N pools should be investigated, as they could conceivably reduce the size of soil inorganic N pools while still providing sufficient N for crop production. Diversified cropping systems may be able to utilize such alternative N ...


Cover Crop Options And Mixes For Upper Midwest Corn-Soybean Systems, Seth R. Appelgate Jan 2016

Cover Crop Options And Mixes For Upper Midwest Corn-Soybean Systems, Seth R. Appelgate

Graduate Theses and Dissertations

The implementation of cover crops in Iowa has the potential to decrease soil erosion, weed density, and nitrate leaching while increasing soil organic carbon. This study investigated nine potential cover crops; winter rye (Secale cereale L.), winter triticale (Triticale hexaploide Lart.), two winter canola (Brassica napus L.) varieties, winter camelina [Camelina sativa (L.) Crantz], spring barley (Hordeum vulgare L.), spring oat (Avena sativa L.), purple top turnip (Brassica rapa L.), and hairy vetch (Vicia villosa Roth). Cover crops were planted as sole crops and selected binary and trinary mixtures. A control treatment of no cover crop was included. Cover crops ...


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 ...


Winter Rye Cover Crop Effect On Corn Seedling Pathogens, Lara Ann Schenck Jan 2015

Winter Rye Cover Crop Effect On Corn Seedling Pathogens, Lara Ann Schenck

Graduate Theses and Dissertations

Cover crops are a valuable management tool to reduce soil and nutrient losses while retaining moisture, improving soil organic matter content, and stabilizing soil N during the winter months when the ground is normally left fallow. Cereal rye (Secale cereale L.) is commonly used as a winter cover crop in the Midwest due to its ability to withstand cold temperatures, reduce soil erosion, and scavenge soil N. However, it has been found that a cereal rye cover crop can sometimes reduce performance and yields in the following corn (Zea mays) crop. Past studies have suggested that reduced corn growth and ...


Biosynthetically Produced Amino Acid Byproducts Can Replace Nitrogen Fertilizers For Corn Production, Juan Carlos Quezada Rivera Jan 2015

Biosynthetically Produced Amino Acid Byproducts Can Replace Nitrogen Fertilizers For Corn Production, Juan Carlos Quezada Rivera

Graduate Theses and Dissertations

Commercial biosynthesis of the amino acids tryptophan (TRP) and lysine (LYS) results in byproducts that are rich in both organic and inorganic compounds. Their nitrogen (N) content may have value as fertilizer N replacement in corn (Zea mays L.) production. We conducted a two-year field study where soil applied pure TRP, its biosynthesis byproduct and LYS byproduct were evaluated as replacements for synthetic N fertilizers in corn production. In-season plant measurements leaf area index , normalized difference vegetation index, grain quality (grain protein and oil concentration) and total N accumulation were not affected by N treatments. Additionally, TRP and LYS biosynthesis ...


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 ...


Emerging Issues In The U.S. Corn Belt: Infection Of Corn By Clavibacter Michiganensis Subsp. Nebraskensis And Use Of Foliar Fungicides To Protect Yield, Salome Mallowa Obura Jan 2015

Emerging Issues In The U.S. Corn Belt: Infection Of Corn By Clavibacter Michiganensis Subsp. Nebraskensis And Use Of Foliar Fungicides To Protect Yield, Salome Mallowa Obura

Graduate Theses and Dissertations

Currently two major issues pertaining to disease management in corn production in the US Corn Belt are the spread of Goss's wilt and leaf blight caused by Clavibacter michiganensis subsp. nebraskensis (Cmn), and the use of foliar fungicides on corn for `plant health' benefits. This dissertation presents data regarding infection of corn by Cmn, and fungicide effects on disease management and yield.

Greenhouse and laboratory research was undertaken to determine if infection of corn by Cmn may occur without severe wounding, such as that caused by hail, sand blasting or wind damage. Corn plants with no obvious wounding were ...


A Comparison Of Carbon Storage Potential In Corn- And Prairie-Based Agroecosystems, Ranae Dietzel Jan 2014

A Comparison Of Carbon Storage Potential In Corn- And Prairie-Based Agroecosystems, Ranae Dietzel

Graduate Theses and Dissertations

Increasing carbon (C) in the soil is important both for removing harmful C from the atmosphere and improving the health of the soil. In this dissertation, I set out to examine how planting and harvesting prairies on soils suitable for corn affected soil C storage potential when compared to corn-based systems. I addressed three questions designed to a) improve our understanding of the fundamental differences between how prairies and corn grow throughout the year, b) test how prairies and corn add C to the soil after establishment, and c) use our current understanding of prairie and corn growth and C ...


Evaluation And Prediction Of Corn Stover Biomass And Composition From Commercially Available Corn Hybrids, Ty Jason Barten Jan 2013

Evaluation And Prediction Of Corn Stover Biomass And Composition From Commercially Available Corn Hybrids, Ty Jason Barten

Graduate Theses and Dissertations

ABSTRACT

High consumption of imported energy in the United States and other countries has increased the interest in bio-renewable sources of energy. This interest has fueled research into crop residues as one potential alternative fuel source. At issue is how to balance economic viability with the sustainability of the endeavor.

The objective of this project was two-fold. The first objective was to quantify the amount and distribution of dry matter, moisture, fiber, and minerals in corn stover from a number of corn hybrids, grown at varying population densities. In this multi-year study we found that of the stover material remaining ...


The Effects Of Starter Fertilizer On Root And Shoot Growth Of Corn Hybrids And Seeding Rates And Plant-To-Plant Variability In Growth And Grain Yield, Warren Pierson Jan 2013

The Effects Of Starter Fertilizer On Root And Shoot Growth Of Corn Hybrids And Seeding Rates And Plant-To-Plant Variability In Growth And Grain Yield, Warren Pierson

Graduate Theses and Dissertations

Starter fertilizer often increases early-season growth of corn; however, yield responses have varied. Yield responses often occur on soils with low soil fertility, however, have occurred on soils with high fertility. Currently, farmers are attempting to reduce plant-to-plant variability in growth and development to maximize grain yield. Farmers have asked if placing starter fertilizer near the seed could reduce plant-to-plant variability with the hypothesis that uniform fertility will result in uniform plants. We conducted two experiments near Ames, Iowa, and Nashua, Iowa with similar treatments and data collection. Starter fertilizer was banded 5 cm below the seed and 5 cm ...


Corn Yield Variability On The Des Moines Lobe Of Iowa: Assessment Of Extent And Soil-Related Causes, Matthew Thomas Streeter Jan 2013

Corn Yield Variability On The Des Moines Lobe Of Iowa: Assessment Of Extent And Soil-Related Causes, Matthew Thomas Streeter

Graduate Theses and Dissertations

Precision agriculture techniques are an essential component to modern row crop agriculture in Iowa and can be used to create crop yield variability maps via geographic information systems. The first objective of this thesis was to explore the methodology that could be used to locate significant long-term corn yield variability on the Iowa Des Moines Lobe. A 158-ha site, consisting mainly of Clarion, Nicollet and Webster soil map units and containing multiple years of geo-referenced corn (Zea mays) yield data was selected. A cluster analysis tool was performed to locate spatially consistent corn yield variability (high, low and mean yield ...


Screening And Genotyping Of Ga1 Gene, And Genotype X Environment Interaction Of Cross Incompatibility In Maize, Moises David Gonzalez Jan 2011

Screening And Genotyping Of Ga1 Gene, And Genotype X Environment Interaction Of Cross Incompatibility In Maize, Moises David Gonzalez

Graduate Theses and Dissertations

The steady increase of genetically-modified (GM) corn (Zea mays L.) in the U.S. makes production of transgene-free corn more difficult to achieve. A strategy to minimize cross-contamination of non-GM corn with GM corn is by using unilateral cross-incompatibility controlled by the Ga1S allele. This allele is transferred to desired germplasm through backcrossing before cross-incompatible Ga1S/Ga1S lines are obtained. The usefulness of this system in preventing cross-fertilization with foreign ga1 pollen might be affected by a combination of environmental effects and heritability of the trait. Methods used for selection of cross-incompatibility in maize are based on differential incompatibility of ...


Establishment Of Switchgrass In Corn Across A Landscape Gradient: Establishment, Yield, And Quality Of Biomass Feedstock, Theodore P. Gunther Jan 2011

Establishment Of Switchgrass In Corn Across A Landscape Gradient: Establishment, Yield, And Quality Of Biomass Feedstock, Theodore P. Gunther

Graduate Theses and Dissertations

Biofuel production in the United States is expected to offset a significant portion of current fuel use through continued use of corn (Zea mays L.) grain and increasingly from alternative feedstocks. Switchgrass (Panicum virgatum L.) is one such species with potential to be used as an alternative feedstock, but establishment is slow and requires long term commitment of land to reach maximum productivity. Switchgrass can be established while producing a corn crop using 2-4-D and atrazine herbicide and seeding switchgrass prior to corn planting, reducing the risk of producing switchgrass as a crop. Relative performance of both corn and switchgrass ...


Did Recurrent Selection For Yield Affect Iowa Stiff Stalk Synthetic Maize Population Grain Fill Characteristics?, Steve James Eichenberger Jan 2011

Did Recurrent Selection For Yield Affect Iowa Stiff Stalk Synthetic Maize Population Grain Fill Characteristics?, Steve James Eichenberger

Graduate Theses and Dissertations

Hybrid maize yield increases, new product development, and increased stress tolerance can be more easily achieved with a better understanding of the physiological and genetic basis for phenotypic changes in response to recurrent selection for yield. The purpose of this study was to identify changes in grain fill characteristics and their interaction with plant density in a closed population and identify a model that accurately predicts grain fill in this population. We hypothesize that recurrent selection for increased yield indirectly impacted the grain fill characteristics of maize including final kernel weight, kernel fill duration, and kernel fill rate in the ...


Utilization Of Active Canopy Sensors For Nitrogen Fertilizer Management In Corn, Daniel W. Barker Jan 2011

Utilization Of Active Canopy Sensors For Nitrogen Fertilizer Management In Corn, Daniel W. Barker

Graduate Theses and Dissertations

The purpose of this research project was to provide much needed information for the development of active canopy sensors as a N fertilizer management decision tool in corn production. Active sensors can be used as an information source regarding plant N status and, can be calibrated to help adjust in-season N applications when corn N deficiencies exist. The adoption of precision farming technology, such as active sensors, is growing in Iowa and much of the U.S. Corn Belt. This Ph.D. dissertation is presented as a series of five chapters. The first chapter is an overview of the dissertation ...


Agronomic And Phenotypic Responses To 75 Years Of Recurrent Selection For Yield In The Iowa Stiff Stalk Synthetic Maize Population, Brent Howard Brekke Jan 2010

Agronomic And Phenotypic Responses To 75 Years Of Recurrent Selection For Yield In The Iowa Stiff Stalk Synthetic Maize Population, Brent Howard Brekke

Graduate Theses and Dissertations

The plant density at which Zea mays L. hybrids achieve maximum grain yield has increased throughout the hybrid era while grain yield on a per plant basis has increased little. Changes in plant traits including grain yield, moisture, test weight, stalk and root lodging, flag leaf angle, anthesis-silking interval(ASI), plant height, tassel branch number, and total number of leaves have been well characterized in comparisons of commercial hybrids representing different eras of hybrid maize production but have yet to be examined in a recurrent selection program.

The objective of this experiment was to determine if direct selection for grain ...


Horticultural Evaluation Of Zein-Based Bioplastic Containers, Matthew Steven Helgeson Jan 2009

Horticultural Evaluation Of Zein-Based Bioplastic Containers, Matthew Steven Helgeson

Graduate Theses and Dissertations

Environmental problems caused by petroleum-based plastics have led to interest in alternatives made from biodegradable polymers (bioplastics), but little effort has been made to evaluate horticultural containers made from these materials. Containers were fabricated from polymers of the corn (Zea mays L.) protein, zein. My first objective was to determine the longevity of zein-based containers under conditions typical of horticultural production. Zein containers of two wall thicknesses were filled with either a peat-based, soilless potting substrate or coarse perlite, and they were irrigated every 2 or 4 days. After 10 weeks, weight loss of containers was determined as a measure ...


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 ...