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Estimating Maize Grain Yield From Crop Biophysical Parameters Using Remote Sensing, Noemi Guindin-Garcia Dec 2010

Estimating Maize Grain Yield From Crop Biophysical Parameters Using Remote Sensing, Noemi Guindin-Garcia

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The overall objective of this investigation was to develop a robust technique to predict maize (Zea mays L.) grain yield that could be applied at a regional level using remote sensing with or without a simple crop growth simulation model. This study evaluated capabilities and limitations of the Moderate Resolution Imaging Spectroradiometer (MODIS) Vegetation Index 250-m and MODIS surface reflectance 500-m products to track and retrieve information over maize fields. Results demonstrated the feasibility of using MODIS data to estimate maize green leaf area index (LAIg). Estimates of maize LAIg obtained from Wide Dynamic Range Vegetation …


The Impact Of Long-Term Tillage, Crop Rotation And N Application On Soil Carbon Sequestration, Agustin Martellotto Dec 2010

The Impact Of Long-Term Tillage, Crop Rotation And N Application On Soil Carbon Sequestration, Agustin Martellotto

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Soil organic carbon (SOC) stock is controlled by many factors, but for given conditions it is the long term summation of the balance between inputs and outputs. Management practices will alter this balance by affecting the system’s productivity and the speed of residue and soil organic matter decomposition. Given that annual changes in SOC are generally small, compared with the large and variable SOC background, long-term experiments, and soil samples taken at the start of experiments (archived samples) are necessary to determine SOC trends over time. Changes in SOC were analyzed for two long-term experiments; one an irrigated site at …


Evaluation Of Novel Input Output Traits In Sorghum Through Biotechnology, Tejinder K. Mall Dec 2010

Evaluation Of Novel Input Output Traits In Sorghum Through Biotechnology, Tejinder K. Mall

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Sorghum [Sorghum bicolor (L.) Moench] is the fifth most important cereal crop world-wide as well as an important source of feed, fiber and biofuel. It is a C4 plant and is well adapted to environments subject to high temperature and water limitation. Despite these agronomic qualities, it suffers from limitations of sensitivity to low temperature and the grain has drawbacks in relation to functionality and digestibility. The objectives of this study are: 1. To promote seed germination at low temperature and to enhance the seedling cold tolerance. 2. To enhance the grain digestibility and functionality. In an attempt to …


Fusarium Head Blight: Winter Wheat Cultivar Responses And Characterization Of Pathogen Isolates, John Fredy Hernandez Nopsa Nov 2010

Fusarium Head Blight: Winter Wheat Cultivar Responses And Characterization Of Pathogen Isolates, John Fredy Hernandez Nopsa

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Fusarium head blight (FHB) is a destructive disease of wheat (Triticum aestivum L). FHB reduces yield and grain quality and causes accumulation of the mycotoxin deoxynivalenol (DON) in grain. Cultivar resistance is one of the most effective management strategies for FHB. Experiments were conducted to 1) identify winter wheat cultivars with resistance to FHB and DON accumulation, 2) determine the effect of winter wheat cultivar on the relationship between FHB and DON concentration, and 3) identify the major species of Fusarium causing FHB in Nebraska and characterize its isolates. Differences (P ≤ 0.05) were detected among cultivars in FHB …


Linkage & Selective Mapping And Qtl Analysis In A Harosoy X Clark Population Of 300 Rils, Sadal Hwang Aug 2010

Linkage & Selective Mapping And Qtl Analysis In A Harosoy X Clark Population Of 300 Rils, Sadal Hwang

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Four of the 12 major Glycine max ancestors of all modern elite U.S.A. soybean cultivars were the grandparents of Harosoy and Clark, so a Harosoy x Clark population would include some of that genetic diversity. A mating of eight Harosoy and eight Clark plants generated eight F1 plants. The eight F1:2 families were advanced via a plant-to-row selfing method to produce 300 F6-derived RILs that were genotyped with 266 SSR, 481 SNP, and 4 classical markers. SNPs were genotyped with the Illumina 1536-SNP assay. Three linkage maps, SSR, SNP, and SSR-SNP, were constructed with a genotyping error of < 1 %. Each map was compared with the published soybean consensus map. The best subset of 94 RILs for a high-resolution framework (joint) map was selected based on the expected bin length statistic computed with MapPop. The QTLs of seven traits measured in a 2-year replicated performance trial of the 300 RILs were identified using composite interval mapping (CIM) and multiple-interval mapping (MIM). QTL x Year effects in multiple trait analysis were compared with results of multiple-interval mapping. QTL x QTL effects were identified in MIM.


Genetic Mapping Of Quantitative Trait Loci Associated With Bioenergy Traits, And The Assessment Of Genetic Variability In Sweet Sorghum (Sorghum Bicolor (L.). Moench), Aatshwaelwe Lekgari Lekgari Aug 2010

Genetic Mapping Of Quantitative Trait Loci Associated With Bioenergy Traits, And The Assessment Of Genetic Variability In Sweet Sorghum (Sorghum Bicolor (L.). Moench), Aatshwaelwe Lekgari Lekgari

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Sweet sorghum, a botanical variety of sorghum is a potential source of bioenergy because high sugar levels accumulate in its stalks. The objectives of this study were to explore the global diversity of sweet sorghum germplasm, and map the genomic regions that are associated with bioenergy traits. In assessing diversity, 142 sweet sorghum accessions were evaluated with three marker types (SSR, SRAP, and morphological markers) to determine the degree of relatedness among the accessions. The traits measured (anthesis date [AD], plant height [PH], biomass yield [BY], and moisture content [MC]) were all significantly different (P<0.05) among accessions. Morphological marker clustered the accessions into five groups based on PH, MC and AD. The three traits accounted for 92.5% of the variation. There were four and five groups based on SRAP and SSR data respectively classifying accessions mainly on their origin or breeding history. The observed difference between SSR and SRAP based clusters could be attributed to the difference in marker type. SSRs amplify any region of the genome whereas SRAP amplify the open reading frames and promoter regions. Comparing the three marker-type clusters, the markers complimented each other in grouping accessions and would be valuable in assisting breeders to select appropriate lines for crossing. In evaluating QTLs that are associated with bioenergy traits, 165 recombinant inbred lines (RILs) were planted at four environments in Nebraska. A genetic linkage map constructed spanned a length of 1541.3 cM, and generated 18 linkage groups that aligned to the 10 sorghum chromosomes. Fourteen QTLs (6 for brix, 3 for BY, 2 each for AD and MC, and 1 for PH) were mapped. QTLs for the traits that were significantly correlated, colocalized in two clusters on linkage group Sbi01b. Both parents contributed beneficial alleles for most of traits measured, supporting the transgressive segregation in this population. Additional work is needed on exploiting the usefulness of chromosome 1 in breeding sorghum for bioenergy.


Xenia Effects On Quality Of Maize Female Inbred In Production Of Hybrid Seeds, Leandro Castañeda Aug 2010

Xenia Effects On Quality Of Maize Female Inbred In Production Of Hybrid Seeds, Leandro Castañeda

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

In Maize (Zea maize L.), cost of hybrid seed production is directly related to the yield and quality of seed obtained per hectare of female parent. It is also important to consider the effects that a male parent can exert on the development of hybrid seed in the female parent. This effect is known as xenia. The objectives of this study were to evaluate xenia effects on 1) yield as 80K units, 2) germination of the hybrid seed and 3) susceptibility of the hybrid seed to mechanical damage. One female inbred and four male inbred lines were selected from a …


Quantitative Trait Loci For Agronomic And End-Use Quality Performance And The Effect Of Soilborne Wheat Mosaic Virus In A Hard Winter Wheat Population In Nebraska, Nicholas A. Crowley Jul 2010

Quantitative Trait Loci For Agronomic And End-Use Quality Performance And The Effect Of Soilborne Wheat Mosaic Virus In A Hard Winter Wheat Population In Nebraska, Nicholas A. Crowley

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

To better understand agronomic and end-use quality in wheat (Triticum aestivum L.) we developed a population containing 154 F6:8 recombinant inbred lines (RILs) from the cross TAM107-R7/Arlin. The parental lines and RILs were phenotyped at six environments in Nebraska and differed for resistance to Wheat soilborne mosaic virus (WSBMV), morphological, agronomic, and end-use quality traits. Additionally, a 2300 cM genome-wide linkage map was created for quantitative trait loci (QTL) analysis. Based on our results across multiple environments, the best RILs could be used for cultivar improvement. The population and marker data are publicly available for interested researchers for future research. …


Grain Yield And Yield-Related Qtl Validation Using Reciprocal Recombinant Inbred Chromosome Lines In Wheat, Neway C. Mengistu Apr 2010

Grain Yield And Yield-Related Qtl Validation Using Reciprocal Recombinant Inbred Chromosome Lines In Wheat, Neway C. Mengistu

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Grain yield and yield-related traits are the most important economic factors for bread wheat (Triticum aestivum L.) improvement. Grain yield (GYLD) and yield-related quantitative trait loci (QTLs) were previously identified by using a population of recombinant inbred chromosome lines (RICLs) developed from cultivar ‘Cheyenne’ (CNN) and its substitution line CNN(WI3A), where the 3A chromosome of cultivar ‘Wichita’ (WI) was substituted for the CNN chromosome 3A. The objectives of this study were to identify and validate GYLD and yield-related QTLs previously identified in CNN(RICLs-3A) studies by using the mirror population WI(RICLs-3A), where chromosome 3A of CNN and WI were now …


Yield Potential And Resource-Use Efficiency Of Maize Systems In The Western U.S. Corn Belt, Patricio Grassini Jan 2010

Yield Potential And Resource-Use Efficiency Of Maize Systems In The Western U.S. Corn Belt, Patricio Grassini

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Maize demand for food, livestock feed, and biofuel is expected to increase substantially. The Western U.S. Corn Belt accounts for 23% of U.S. maize production, and irrigated maize accounts for 43 and 58% of maize land area and total production, respectively, in this region. The most sensitive parameters (yield potential [YP], water-limited yield potential [YP-W], yield gap between actual yield and YP, and resource-use efficiency) governing performance of maize systems in the region are lacking. A simulation model was used to quantify YP under irrigated and rainfed conditions based on weather data, soil properties, and crop management at 18 locations. …


Genetic Diversity Of Wheat Cultivars From Turkey And U.S. Great Plains, Anyamanee Auvuchanon Jan 2010

Genetic Diversity Of Wheat Cultivars From Turkey And U.S. Great Plains, Anyamanee Auvuchanon

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Genetic diversity of wheat cultivars from Turkey and the Great Plains was studied under the hypothesis ‘Turkey’ wheat originated from Turkey and is the original hard red winter wheat landrace in the Great Plains. Wheat cultivars in Turkey and the Great Plains were selected for adaptation in two countries which were similar in climate. Twenty-two Turkish and twenty-three Great Plains wheat cultivars were selected for this study using SSR markers, agronomic, and end-use quality traits data. Wheat cultivars were clustered into five groups based on SSR markers and the clustering largely followed their countries of origin and pedigree. Modern Great …