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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

Maize

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Assessment Of Inducibility And Spontaneous Haploid Genome Doubling In Maize (Zea Mays L.), Benjamin Thomas Trampe Jan 2019

Assessment Of Inducibility And Spontaneous Haploid Genome Doubling In Maize (Zea Mays L.), Benjamin Thomas Trampe

Graduate Theses and Dissertations

Maize is a staple food, fuel, and feed crop grown around the world. Doubled haploid technology allows for the quick of development of inbred lines for hybrid development. The maternal in vivo doubled haploid system has gained rapid adoption by the maize breeding sector within the last 10 years. There have been significant improvements in the doubled haploid technology, which made it commercially viable. Within the doubled haploid system, there is limited genetic information about the two important traits that control the ability of generating doubled haploids, which are inducibility and spontaneous haploid genome doubling. Better understanding of these two ...


Characterizing Climate Change In The Midwest: Magnitude Of Warming And Plausibility Of Adaptation Strategies For Maize-Based Systems, Lori Jean Abendroth Jan 2019

Characterizing Climate Change In The Midwest: Magnitude Of Warming And Plausibility Of Adaptation Strategies For Maize-Based Systems, Lori Jean Abendroth

Graduate Theses and Dissertations

Maize-based agricultural systems dominate the U.S. Midwest landscape and maintaining productive systems in the short- and long-term are high priorities for the agricultural sector. Climate change has and will continue to alter the environment in which farmers produce their crops. Information and recommendations are necessary for understanding the magnitude of warming and adaptation strategies that can mitigate intensified precipitation events, moisture shortages, and increased temperatures. The multi-faceted changes in temperature were aggregated using thermal time as an agro-climate index to describe the warming relevant for producing maize. Across 1054 counties, the change in thermal time since 1950 was disproportionally ...


Genetic Dissection And Prediction Of Leaf Angle Across The Maize Canopy, Matthew James Dzievit Jan 2019

Genetic Dissection And Prediction Of Leaf Angle Across The Maize Canopy, Matthew James Dzievit

Graduate Theses and Dissertations

Maize’s (Zea mays L.) leaf angle has changed over the last 60 years because of intense selection pressure for high yielding hybrids under increasing planting densities. Leaf angle plays a crucial role in distributing sunlight to different canopy leaves and its optimization across the canopy is essential for increasing productivity per unit of land. This dissertation seeks to explain and predict leaf angle variation across multiple canopy levels in maize through genetic mapping, meta-analysis, and genomic prediction.

Two genetic mapping populations were developed using inbred lines B73, PHW30, and Mo17 that represent important maize heterotic groups. The two populations ...


Cover Crop Effects On Maize Productivity: Insights From Statistical And Process-Based Models, Guillermo Marcillo Jan 2018

Cover Crop Effects On Maize Productivity: Insights From Statistical And Process-Based Models, Guillermo Marcillo

Graduate Theses and Dissertations

Winter cover crops can be an effective strategy to buffer soil and water impairing effects from intensively managed agriculture. While cover crops have shown potential to sequester off-season nitrate, control weeds, or promote nutrient cycling, knowledge gaps persist in regard to maize impacts driven by cover crop decision making. In this context, statistical and process-based models can be valuable tools for predicting changes in maize systems that include a winter cover crop. In a meta-analysis combining peer-reviewed research from several regions in the US, grain yields were found to change between 0 and 21% when maize (Zea mays L.) followed ...


Quantifying The Effects Of Daily Light Integral Or Photoperiod On Maize Tassel Morphology Across Developmental Stages, Elizabeth Ann Trecker Jan 2018

Quantifying The Effects Of Daily Light Integral Or Photoperiod On Maize Tassel Morphology Across Developmental Stages, Elizabeth Ann Trecker

Graduate Theses and Dissertations

ABSTRACT

Maize (Zea mays L.) is an important agronomic crop throughout the world. Maize seed production and trait introgression is performed in both field and greenhouse settings (which allow for continual production seasons). The winter months within the greenhouses produce maize tassels with increased barren tassel branches (suppressed anther production) and the hypothesis is that the most limiting factor is daily light integral (DLI). Growing maize year-round in temperate regions, such as the northern part of the United States, requires the use-of greenhouse production. The low light intensities of these regions in the winter months creates a need for supplemental ...


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 ...


Molecular And Phenotypic Characterization Of Doubled Haploid Exotic Introgression Lines For Nitrogen Use Efficiency In Maize, Darlene Lonjas Sanchez Jan 2017

Molecular And Phenotypic Characterization Of Doubled Haploid Exotic Introgression Lines For Nitrogen Use Efficiency In Maize, Darlene Lonjas Sanchez

Graduate Theses and Dissertations

Nitrogen (N) is an important macroelement for promoting crop growth and development, and is essential for increased grain yield. However, less than half of the N fertilizer applied goes into the grain, and excess N goes back into the environment. Developing maize hybrids with improved nitrogen use efficiency (NUE) can help minimize N losses, and in turn reduce adverse ecological, economical, and health consequences. The root system plays a major role in the acquisition of N, as well as water and nutrients; thus, selecting for root architecture traits ideal for N uptake might help improve NUE in maize. This project ...


Assessment Of Tassel Initiation In Maize Inbred Lines Under Field Conditions Using Florigen Expression, Juan Pablo San Martin Toloza Jan 2016

Assessment Of Tassel Initiation In Maize Inbred Lines Under Field Conditions Using Florigen Expression, Juan Pablo San Martin Toloza

Graduate Theses and Dissertations

Synchronizing male and female flowers in hybrid maize (Zea mays L.) seed production is critical for maximum yields of high quality seed. Many factors may delay planting in a particular region beyond the optimal planting time, creating a different temperature and photoperiod environment interacting with a female and male maize inbred pair. Maize ontogeny is controlled by temperature and photoperiod, although publications disagree on the magnitude of impact these factors have. The transition of the shoot apical meristem (SAM) from vegetative to reproductive growth in maize it is called tassel initiation (TI). TI is always preceded by an accelerated expression ...


Brassinosteroid And Gibberellin Control Of Plant Height In Maize (Zea Mays. L), Songlin Hu Jan 2016

Brassinosteroid And Gibberellin Control Of Plant Height In Maize (Zea Mays. L), Songlin Hu

Graduate Theses and Dissertations

Brassinosteroids (BRs) and gibberellins (GAs) are two major plant hormones involved in many plant developmental processes. However, the knowledge of BR and GA control of agronomic traits in maize is limited compared to model species Arabidopsis and rice, especially BR. This PhD project focused on BR and GA control of plant height from genetics and plant biology perspectives, as these two plant hormones have shown great impact for shaping plant height, and a short/tall stature of maize height is beneficial for grain/biomass production, respectively. We introgressed multiple exotic accessions into two maize heterotic groups Stiff Stalk and Non ...


Biomass Sorghum And Maize Have Similar Water-Use-Efficiency Under Non-Drought Conditions In The Rain-Fed, Midwest Us, Matthew Roby Jan 2016

Biomass Sorghum And Maize Have Similar Water-Use-Efficiency Under Non-Drought Conditions In The Rain-Fed, Midwest Us, Matthew Roby

Graduate Theses and Dissertations

Biomass sorghum [Sorghum bicolor (L.) Moench.] is a candidate bioenergy feedstock in the Midwest, US. Research suggests that biomass sorghum is more drought tolerant and has higher water-use-efficiency (WUE; the ratio of cumulative biomass production to total evapotranspiration; g kg-1) than Zea mays (maize) in water-limiting environments. However, comparisons of the seasonal evapotranspiration (total ET) and WUE of biomass sorghum and maize have focused on irrigated systems and are scarce for the rain-fed, Midwest. We conducted a side-by-side comparison of the total ET and WUE of maize and biomass sorghum at a site within the US Corn Belt. Total ET ...


Effects Of Recurrent Selection For Yield On Plant Growth Across Planting Densities In Maize (Zea Mays L.), Michael Jonathan Stein Jan 2016

Effects Of Recurrent Selection For Yield On Plant Growth Across Planting Densities In Maize (Zea Mays L.), Michael Jonathan Stein

Graduate Theses and Dissertations

Breeding for higher grain yield in maize (Zea mays L.), utilizing increased selection densities, has produced varieties that are adapted to grow at higher population densities. The effects of increased planting density on grain yield and final phenotypes are well known, but the effects of density on plant growth across the growing season have been less widely characterized. The objectives of this study were: 1) examine the effects of high planting density on growth rates, growth timing, and biomass partitioning of the ear, stalk, and tassel; 2) characterize the difference in density effects in maize populations before and after recurrent ...


Improvements To The Maize (Zea Mays L.) In Vivo Maternal Doubled Haploid System, Gerald Neil De La Fuente Jan 2015

Improvements To The Maize (Zea Mays L.) In Vivo Maternal Doubled Haploid System, Gerald Neil De La Fuente

Graduate Theses and Dissertations

The maize (Zea mays L.) in vivo maternal doubled haploid system has been widely applied to maize breeding and genetics in recent decades and is an important part of the majority of public and private maize breeding programs today. The principal advantage of the doubled haploid system is the ability to generate completely homozygous inbred lines in as little as two seasons. Other advantages to this system include more rapid integration of loci of interest and increased usefulness over traditional lines developed through self-pollination. In this dissertation, some of the major problems in the maternal doubled haploid system are addressed ...


Identification Of Qtl Associated With Nitrogen Metabolism In A Maize (Zea Mays L. Ssp. Mays) Testcross Population, Ignacio Trucillo Silva Jan 2015

Identification Of Qtl Associated With Nitrogen Metabolism In A Maize (Zea Mays L. Ssp. Mays) Testcross Population, Ignacio Trucillo Silva

Graduate Theses and Dissertations

Maize is a widely cultivated crop in the world and its production relies heavily on nitrogen (N) fertilization. N is an essential mineral nutrient for plant growth and development. However, during the last decades excessive quantities of N have been applied by farmers, a surplus to what maize plants can uptake, and several problems have arisen, such as pollution of the ecosystem and an economic loss to farmers. Breeding maize hybrids that are more efficient in the use of N is a long term goal for plant breeders. Nonetheless, previous to breeding, the genetic basis of N-metabolism in maize would ...


Plant Molecular Farming For The Production Of Industrial Enzyme And Vaccines, Hartinio N. Nahampun Jan 2015

Plant Molecular Farming For The Production Of Industrial Enzyme And Vaccines, Hartinio N. Nahampun

Graduate Theses and Dissertations

Since the realization of plant genetic modification, transgenic plants have been utilized as platform for the production of valuable recombinant proteins or also known as plant molecular farming (PMF). The plant offers an economical system to reduce cost, the possibility of large scale production and is free of pathogens. The plant also provides versatility o products to accumulate from industrial enzymes, peptides, and pharmaceuticals. Recent advancement of RNA as regulator of gene expression and antiviral responses has shown a new area of research where transgenic plants are used to accumulate therapeutic RNAs. In this study, the reliability of transgenic plants ...


Analysis Of Cytokinin-Induced Maize Leaf Developmental Changes And Interacting Genetic Modifiers, James Francis Cahill Jan 2015

Analysis Of Cytokinin-Induced Maize Leaf Developmental Changes And Interacting Genetic Modifiers, James Francis Cahill

Graduate Theses and Dissertations

Four distinct segments define the maize leaf along the proximal-distal axis: the proximal sheath and the distal blade, which are separated by the ligule and auricle. The process of maize leaf morphogenesis, patterning and development requires the coordination of a number of proteins and hormones. The semi-dominant gain-of-function mutant Hairy sheath frayed1 (Hsf1) disrupts a number of leaf growth parameters: (i) leaves are shorter and more narrow, (ii) an increased density of macrohairs are apparent on the abaxial sheath and adaxial blade and (iii) the normal proximal-distal leaf pattern is disrupted, resulting in outgrowths, or prongs, of ectopic sheath, auricle ...


Influence Of Corn Seeding Rate, Soil Attributes, And Topographic Characteristics On Grain Yield, Yield Components, And Grain Composition, Mark Allen Licht Jan 2015

Influence Of Corn Seeding Rate, Soil Attributes, And Topographic Characteristics On Grain Yield, Yield Components, And Grain Composition, Mark Allen Licht

Graduate Theses and Dissertations

Adoption of variable seeding rates has increased dramatically in recent years due to ability and feasibility of determining soil and topographic variability within fields. This research explores soil and topographic attribute interactions with seeding rate and the effect they have on corn yield, yield components, and grain composition. Experimental treatments included five seeding rates (61,750; 74,100; 86,450; 98,800; and 111,150 seeds ha-1) in a randomized complete block design in three central Iowa fields from 2012 to 2014. Soil samples were analyzed for available P, exchangeable K, pH, soil organic matter, cation exchange capacity, and texture ...


Gametophytic Cross-Incompatibility In Maize: Resequencing The Ga1 Locus, Marianne Lynn Emery Jan 2015

Gametophytic Cross-Incompatibility In Maize: Resequencing The Ga1 Locus, Marianne Lynn Emery

Graduate Theses and Dissertations

Maize is an important staple crop for many countries. Culture dictates maize use, processing, and incorporation into foods. The crop has a rich history of domestication and improvement. With its relative ease of genetic manipulation, maize is considered a model crop for plant genetic experimentation. Recent biotechnological advances, as well as the completed B73 reference genome sequence, have expedited maize improvement. One such profound advance that has greatly increased profitability of maize is the use of transgenes. Despite the many benefits, transgenic plants are problematic when they contaminate transgene-free maize. Maintaining the purity of transgene-free maize is crucial, but often ...


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 ...


Regulation Of Shoot Development In Maize Via Brassinosteroid Signaling, Gokhan Kir Jan 2015

Regulation Of Shoot Development In Maize Via Brassinosteroid Signaling, Gokhan Kir

Graduate Theses and Dissertations

Brassinosteroids (BR) are a class of phytohormones with many important roles in plant growth and development. Compared to other model organisms BR signaling is poorly understood in maize. To study BR signaling's role in maize growth and development we suppressed two members of the BR signaling pathway, BRI1 and BIN2, by RNAi approach. BLAST searches and phylogenetic analyses suggested that there are two BRI1 copies and three BRI1-like genes (BRL) homologs in maize. bri1b, which is located on chr 5, was incomplete in databases, but via subsequent cloning and sequencing was found to be an intact and expressed gene ...


Germplasm Enhancement Of Maize: Utilization Of Doubled Haploid Breeding On Adapted Tropical Sources, Andrew Smelser Jan 2014

Germplasm Enhancement Of Maize: Utilization Of Doubled Haploid Breeding On Adapted Tropical Sources, Andrew Smelser

Graduate Theses and Dissertations

The allelic diversity (AD) project of the Germplasm Enhancement of Maize program utilized the double haploid (DH) breeding method to expedite release of lines from 300 exotic maize races. Differential effects on haploid induction rates (HIR) and chromosome doubling rates (DR) associated with the recurrent parents PHB47 and PHZ51, the elevation that the race is traditionally grown at, and the race itself were examined. Races from the AD project were grouped by elevation (high, middle, or low altitude) of their country of origin. Six races per elevation were randomly selected and backcrossed using both recurrent parents to generate 36 populations ...


Genetic Analysis Of The Ibm2syn10-Dh Maize Population For Response To Low And High Nitrogen Input, Pedro José Gonzalez-Portilla Jan 2014

Genetic Analysis Of The Ibm2syn10-Dh Maize Population For Response To Low And High Nitrogen Input, Pedro José Gonzalez-Portilla

Graduate Theses and Dissertations

Maize growth and development depends highly in the capacity of the plants to absorb Nitrogen (N) from the soil. Producing a high-yielding maize crop that requires less N input is currently one important goal of maize breeding programs. In order to understand the dynamics of N use in maize, the study of phenotypic and genetic response to N deficiency must be performed. Using lines from the high resolution IBM2Syn10-DH population, the goals of this study were: 1) to identify the phenotypic response of the root system architecture (RSA) of 14-day old maize seedlings grown under contrasting levels of N; 2 ...


Controlling Biomass Properties For Optimizing Fast Pyrolysis Products, Brandon Jeffrey Jan 2013

Controlling Biomass Properties For Optimizing Fast Pyrolysis Products, Brandon Jeffrey

Graduate Theses and Dissertations

The energy future of the United States is likely to include a large number of traditional and alternative energy sources and technologies. Fast pyrolysis has been identified as one of the alternative energy conversion processes that could play a role in this energy future. Fast pyrolysis produces solid (biochar), liquid (bio-oil), and gaseous products (syngas). Bio-oil is the main component (up to 80%) and has a number of potentially useful applications. Bio-oil composition is complex and is related to cell wall composition, as compounds in the bio-oil derive from the individual cell wall components cellulose, hemicelluloses, and lignin.

While a ...


Candidate Gene Based Association Study For Nitrogen Use Efficiency And Associated Traits In Maize, Bharath Kumar Thamasandra Narayana Jan 2013

Candidate Gene Based Association Study For Nitrogen Use Efficiency And Associated Traits In Maize, Bharath Kumar Thamasandra Narayana

Graduate Theses and Dissertations

Nitrogen (N) is a major macronutrient used in cereal production that stimulates plant growth and development. Demand for N fertilizer has been growing steadily at an annual growth rate of 1.8 percent due to the continuous increase in the cereal growing areas (mainly maize), and N is needed to maximize yield potential of agricultural crops. It has been estimated that N fertilizer used by cereals is only 33%. The rest of the applied N fertilizer is lost in the combination of surface runoff, gaseous release from soil, leaching and de-nitrification processes. In the future, for a sustainable crop production ...


Density Response Of Maize Canopy Architecture In Adapted And Unadapted Synthetic Populations, Naser Bader Alkhalifah Jan 2013

Density Response Of Maize Canopy Architecture In Adapted And Unadapted Synthetic Populations, Naser Bader Alkhalifah

Graduate Theses and Dissertations

ABSTRACT

Since the 1950's, the average maize grain yield, on a per unit area basis, has risen exponentially and without a pause. Associated with this increase have been changes in shoot morphology which permit more light penetration into the canopy. Changes in plant traits including plant height, leaf number, individual leaf area, vertical leaf angle, tassel size and weight, and leaf area density distribution along the main stem have been reported in the literature; however, the response of canopy components to changes in plant density has not been examined in closed populations and at today's densities. The objective ...


Tassels Replace Upper Ears1 Encodes A Putative Transcription Factor That Regulates Maize Shoot Architecture By Multiple Pathways, Wei Li Jan 2012

Tassels Replace Upper Ears1 Encodes A Putative Transcription Factor That Regulates Maize Shoot Architecture By Multiple Pathways, Wei Li

Graduate Theses and Dissertations

Plant shoot architecture has many features including inflorescence sex, branching and internode elongation, which is largely controlled by the activities of shoot apical meristem (SAM) and axillary meristems (AxM). The pleiotropic maize mutant tassels replace upper ears1 (tru1) shows reduced apical dominance with elongated upper shanks tipped by lateral tassels and shortened upper stem, altered tassel phenotypes with shortened tassel length and branch length, and reduced tassel branch number. To investigate the effect of tru1 on shoot architecture, morphological analysis of tru1-ws mutant was performed, including treatments of supplemental gibberellic acid (GA3), far red (FR) light and decapitation, and genetic ...


Genetic Dissection Of Canonical Models Of Maize Kernel Growth And Development, Kendra Ann Meade Jan 2012

Genetic Dissection Of Canonical Models Of Maize Kernel Growth And Development, Kendra Ann Meade

Graduate Theses and Dissertations

An understanding of the genetics of maize kernel growth and development will provide valuable insight into a complicated physiological process. The genetics of kernel growth and development is of interest not only to plant scientists who seek to understand the underlying molecular mechanism but also to plant breeders who seek to develop improved hybrids with faster growing, larger kernels. In order to better understand the genetics of kernel growth and development, biomass accumulation and moisture content were observed in a sample of hybrids and a set of doubled haploids derived from a cross of elite inbred lines and testcrossed to ...


Strategies For Recombinant Protein Production In Maize, Xing Xu Jan 2012

Strategies For Recombinant Protein Production In Maize, Xing Xu

Graduate Theses and Dissertations

Maize is not only one of the world's most important crops, but it is also the first field-grown plant-based recombinant expression system developed for commercial purposes. With advantages of low cost, high yield, high protein stability, and well-developed transformation technology over other plant systems, maize is considered to be an ideal recombinant production system. However, there are three major challenges limiting the use of maize for producing recombinant proteins: 1) maize lacks mammalian-like post-translational modification ability that may be required for pharmaceutical and industrial proteins; 2) transgenic pollen containment in open-field production; and 3) low expression of recombinant products ...


Field Characterization Of Maize Photosynthesis Response To Light And Leaf Area Index Under Different Nitrogen Levels: A Modeling Approach, Laila Alejandra Puntel Jan 2012

Field Characterization Of Maize Photosynthesis Response To Light And Leaf Area Index Under Different Nitrogen Levels: A Modeling Approach, Laila Alejandra Puntel

Graduate Theses and Dissertations

A better characterization of nitrogen (N) demand is essential for an improved estimation of N requirements by maize crops. Crop growth models can provide a tool for greater understanding of the variable responses of yield to different N levels observed experimentally. Photosynthesis-based models require a detail characterization of the effect of N on the photosynthetic machinery of the leaves and leaf area index (LAI) for capturing N variability and demand. Photosynthetic light response curve at different N levels (0, 90, and 225 kg ha-1) were measured in a field experiment conducted at the Agronomy Research Farm, Iowa State University during ...


Breeding For Cob Traits In Maize, Constantin Jansen Jan 2012

Breeding For Cob Traits In Maize, Constantin Jansen

Graduate Theses and Dissertations

The advantages of maize cobs as cellulosic feedstock are based on their compact architecture and high fraction of cellulose and hemicellulose. Cobs are low in ash content, nutrients, and minerals and their harvest will likely not deplete the soil. Dual-purpose maize, with larger cob biomass and high tissue density, could reduce transport costs providing more farmers with additional income from cob sales. The objective of this study was to lay the foundation for developing dual-purpose maize, combining high cob biomass and grain yield. This included a morphological and genetic analysis of cob characters under varying environments, as well as their ...


New Methods For Haploid Selection In Maize, Yichia Tseng Jan 2012

New Methods For Haploid Selection In Maize, Yichia Tseng

Graduate Theses and Dissertations

The major aim of this study was to evaluate new methods to select haploids for maize breeding. The first method was to evaluate different inbreds for sensitivity to herbicides that could be developed as a tool for haploid selection, and the second was to evaluate automated sorting based on near-infrared reflectance spectroscopy (NIRS) and SIMCA analysis.