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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

QTL

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Genetic And Brassinosteroid Control Underlying Leaf Angle Variation Across The Canopy In Sorghum, Maria Betsabe Mantilla Perez Jan 2018

Genetic And Brassinosteroid Control Underlying Leaf Angle Variation Across The Canopy In Sorghum, Maria Betsabe Mantilla Perez

Graduate Theses and Dissertations

Leaf angle, the inclination between the midrib of a leaf blade and the stem, is one of the main determinants of crop productivity. Plants with an upright leaf angle on the top and more horizontal towards the bottom can maximize their light interception and photosynthetic capacity, increasing yield per plant and unit of land. Experiments to investigate the genetic control of leaf angle have been routinely designed on the use of one or two arbitrarily selected leaves, or merged the data from multiple leaves on an average value. This approach has limited our understanding of the control of leaf angle ...


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 ...


Genome Wide Association Study Of Seed And Seedling Root Traits In Sunflower, Ze Tian Fang Jan 2017

Genome Wide Association Study Of Seed And Seedling Root Traits In Sunflower, Ze Tian Fang

Graduate Theses and Dissertations

Cultivated sunflower (Helianthus annuus L.) is an internationally important crop harvested for seed oil and confectionary purposes. Sunflower unlike many other crops, has an extensive root system that can provide drought avoidance under water limiting conditions in the field. This genome wide association (GWA) study utilized 2D images of seeds and seedling roots from a diverse panel of sunflower genotypes (n = 288 lines) for QTL detection. The subsequent analyses of these images revealed vast phenotypic variation in total root length (mean = 169 cm, SD = 81 cm) and primary root length (mean = 29 cm, SD = 7 cm). ANOVA and PCA based ...


Genetic And Physiologic Analyses Of Soybean Grain Yields In Water Limited Environments, Dawn Gibson Jan 2015

Genetic And Physiologic Analyses Of Soybean Grain Yields In Water Limited Environments, Dawn Gibson

Graduate Theses and Dissertations

Increasing grain yield in soybean is an important breeding goal for plant breeders. While identification of yield QTL can result in identification of genomic regions for increasing yield, these regions are often not consistent across environments due to genetic and environment interactions. Water limitation for crop growth is one such environment in which yield QTL are not consistent. Water limitations during grain fill can be especially devastating to the final yield of a crop. The objective of this study was to identify and then map QTL in three families of recombinant inbred lines (RILs) developed from two plant introductions and ...


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 ...


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 ...


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 ...


Effects Of Environment And Planting Density On Plant Stature, Flowering Time, And Ear Set In Ibm Populations Of Maize, Sara Jane Helland Jan 2012

Effects Of Environment And Planting Density On Plant Stature, Flowering Time, And Ear Set In Ibm Populations Of Maize, Sara Jane Helland

Graduate Theses and Dissertations

Plant stature, flowering time and ear set are related to maturity, disease and insect resistance, drought tolerance, root lodging and yield, which are all major trait targets for maize breeders. In an effort to understand the effects of year, location, and planting density on these traits, we grew the IBMRIL and IBMDH populations in high and low density at several locations in the cornbelt over a period of years. The effects of temperature, precipitation, and solar radiation at key crop growth phases were quantified for each trait using partial least squares regression. The heritability of each trait across high and ...


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 ...