Plant Sciences Commons^™

Benchmarking On-Farm Maize Nitrogen Balance In The Western U.S. Corn Belt, Fatima Amor Tenorio

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

A nitrogen (N) balance, calculated as the difference between N inputs and grain-N removal, provides an estimate of the potential N losses. We used N balance with other N-related metrics (partial factor productivity for N inputs, and yield-scaled N balance), to benchmark maize yields in relation with N input use in the US Corn Belt. We first used experimental data on grain-N concentration (GNC) to assess variation in this parameter due to biophysical and management factors. Subsequently, we used N balance and N-related metrics to benchmark yields in relation with N inputs in irrigated and rainfed fields in Nebraska using …

Transgenic Control Of Aflatoxin Contamination In Maize Through Host-Induced Gene Silencing Targeting Aspergillus Flavus Genes Encoding Polygalacturonase (P2c) And Versicolorin Dehydrogenase (Aflm), Yenjit Raruang

LSU Doctoral Dissertations

Maize (Zea mays L.) is susceptible to Aspergillus flavus infection and subsequent contamination with aflatoxins, the most potent naturally produced carcinogenic secondary metabolites. Here, the A. flavus gene aflM encoding the versicolorin dehydrogenase in aflatoxin biosynthesis and the p2c gene encoding the polygalacturonase that is involved in infection were selected as targets for suppression through host induced gene silencing (HIGS). A HIGS vector targeting these genes was constructed and introduced into immature B104 maize embryos. Thirteen out of fifteen p2c transformation events and six out of seven aflM events were confirmed positive by PCR. Kernels containing the p2c gene …

Regenerating Agricultural Landscapes With Perennial Groundcover For Intensive Crop Production, Kenneth J. Moore, Robert P. Anex, Amani E. Elobeid, Shuizhang Fei, Cornelia B. Flora, A. Susana Goggi, Keri L. Jacobs, Prashant Jha, Amy L. Kaleita, Douglas L. Karlen, David A. Laird, Andrew W. Lenssen, Thomas Lubberstedt, Marshall D. Mcdaniel, D. Raj Raman, Sharon L. Weyers

Douglas L Karlen

The Midwestern U.S. landscape is one of the most highly altered and intensively managed ecosystems in the country. The predominant crops grown are maize (Zea mays L.) and soybean [Glycine max (L.) Merr]. They are typically grown as monocrops in a simple yearly rotation or with multiple years of maize (2 to 3) followed by a single year of soybean. This system is highly productive because the crops and management systems have been well adapted to the regional growing conditions through substantial public and private investment. Furthermore, markets and supporting infrastructure are highly developed for both crops. As maize and …

New Approaches To Use Genomics, Field Traits, And High-Throughput Phenotyping For Gene Discovery In Maize (Zea Mays), Zhikai Liang

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

Maize is one of major crop species over the world. With lots of genetic resources and genomic tools, maize also serves as a model species to understand genetic diversity, facilitate the development of trait extraction algorithms and map candidate functional genes. Since the first version of widely used B73 reference genome was released, independent research groups in the maize community propagated seeds themselves for further research purposes. However, unexpected or occasional contamination may happen during this process. The first study in this thesis used public RNA-seq data of B73 from 27 research groups across three countries for calling single nucleotide …

Extreme‐Phenotype Genome‐Wide Association Study (Xp‐Gwas): A Method For Identifying Trait‐Associated Variants By Sequencing Pools Of Individuals Selected From A Diversity Panel, Jinliang Yang, Haiying Jiang, Cheng-Ting Yeh, Jianming Yu, Jeffrey A. Jeddeloh, Dan Nettleton, Patrick S. Schnable

Dan Nettleton

Although approaches for performing genome‐wide association studies (GWAS) are well developed, conventional GWAS requires high‐density genotyping of large numbers of individuals from a diversity panel. Here we report a method for performing GWAS that does not require genotyping of large numbers of individuals. Instead XP‐GWAS (extreme‐phenotype GWAS) relies on genotyping pools of individuals from a diversity panel that have extreme phenotypes. This analysis measures allele frequencies in the extreme pools, enabling discovery of associations between genetic variants and traits of interest. This method was evaluated in maize (Zea mays) using the well‐characterized kernel row number trait, which was …

Extensive Tissue-Specific Transcriptomic Plasticity In Maize Primary Roots Upon Water Deficit, Nina Opitz, Caroline Marcon, Anja Paschold, Waqas Ahmed Malik, Andrew Lithio, Ronny Brandt, Hans-Peter Piepho, Dan Nettleton, Frank Hochholdinger

Dan Nettleton

Water deficit is the most important environmental constraint severely limiting global crop growth and productivity. This study investigated early transcriptome changes in maize (Zea mays L.) primary root tissues in response to moderate water deficit conditions by RNA-Sequencing. Differential gene expression analyses revealed a high degree of plasticity of the water deficit response. The activity status of genes (active/inactive) was determined by a Bayesian hierarchical model. In total, 70% of expressed genes were constitutively active in all tissues. In contrast, <3% (50 genes) of water deficit-responsive genes (1915) were consistently regulated in all tissues, while >75% (1501 genes) were specifically regulated in a single root tissue. Water deficit-responsive genes were most numerous in the …

Mu Transposon Insertion Sites And Meiotic Recombination Events Co-Localize With Epigenetic Marks For Open Chromatin Across The Maize Genome, Sanzhen Liu, Cheng-Ting Yeh, Tieming Ji, Kai Ying, Haiyan Wu, Ho Man Tang, Yan Fu, Daniel S. Nettleton, Patrick S. Schnable

Dan Nettleton

The Mu transposon system of maize is highly active, with each of the ∼50–100 copies transposing on average once each generation. The approximately one dozen distinct Mutransposons contain highly similar ∼215 bp terminal inverted repeats (TIRs) and generate 9-bp target site duplications (TSDs) upon insertion. Using a novel genome walking strategy that uses these conserved TIRs as primer binding sites, Mu insertion sites were amplified from Mu stocks and sequenced via 454 technology. 94% of ∼965,000 reads carried Mu TIRs, demonstrating the specificity of this strategy. Among these TIRs, 21 novel Mu TIRs were discovered, revealing additional complexity of …

Meta-Analysis Of Yield Response Of Foliar Fungicide-Treated Hybrid Corn In The United States And Ontario, Canada, Kiersten A. Wise, Damon Smith, Anna Freije, Daren S. Mueller, Yuba Kandel, Tom Allen, Carl A. Bradley, Emmanuel Byamukama, Martin Chilvers, Travis Faske, Andrew Friskop, Clayton Hollier, Tamra A. Jackson-Ziems, Heather Kelly, Bob Kemerait, Paul Price Iii, Alison Robertson, Albert Tenuta

Plant Pathology Faculty Publications

Background

Foliar fungicide applications to corn (Zea mays L.) occur at one or more application timings ranging from early vegetative growth stages to mid-reproductive stages. Previous studies indicated that fungicide applications are profitable under high disease pressure when applied during the tasseling to silking growth stages. Few comprehensive studies in corn have examined the impact of fungicide applications at an early vegetative growth stage (V6) compared to late application timings (VT) for yield response and return on fungicide investment (ROI) across multiple locations.

Objective

Compare yield response of fungicide application timing across multiple fungicide classes and calculate the probability …

Evaluation Of Foliar Insecticides For The Control Of Western Bean Cutworm In Field Corn, 2018, Katharine A. Swoboda-Bhattarai, Samantha R. Daniel, Julie A. Peterson

West Central Research and Extension Center, North Platte

The objectives of this field trial were to evaluate the efficacy of single applications of foliar insecticides at preventing feeding damage by the western bean cutworm (WBC), an important pest of corn and dry beans that has undergone a rapid range expansion into the eastern Corn Belt during the last 18 yr. This study was conducted within the historic range of WBC, at the University of Nebraska-Lincoln’s Henry J. Stumpf International Wheat Center in Perkins County, NE (40.856851°N, −101.701335°W). An RCB design with a total of 16 treatments (including an untreated check) and four replications was used. Plots measured 20 …

Validation Of Candidate Loci For Maize Regrowability And Selection Of Near Isogenic Lines For The Loci, Tajbir Raihan

Electronic Theses and Dissertations

Developing perennial grain crops is an effective way for sustainable agriculture and it can be a tool for the betterment of the overall ecosystem. To understand how perenniality works in perennial species, we made a cross between Zea diploperennis and maize (Z. mays) inbred line B73. F1 hybrids produced from this cross were selfed to get the F2 population and later the F2 population underwent Genotyping-By- Sequencing (GBS) analysis. Based on the candidate loci identified on chromosome 2 and chromosome 7 from GBS, SNP-specific markers were developed from the candidate locus interval and used to genotype the F2 …

Effect Of Late Nitrogen Fertilization On Grain Yield And Grain Filling In Corn, J. A. Fernandez, I. A. Ciampitti

Kansas Agricultural Experiment Station Research Reports

For decades, yield improvement in corn has been accompanied by an increase in plant nitrogen (N) uptake. Modern hybrids are absorbing more N during reproductive stages, while delaying N remobilization to the grain for later in the growing season. To evaluate the effect of late-season N applications in distinct corn genotypes, grain yield and grain filling parameters were evaluated in field experiments under early and late N regimes during 2017 and 2018 growing seasons. Hybrids with different release years (3394, 1990s; P1151, 2000s; and P1197, 2016) and contrasting N application scenarios (including a zero-N control) were evaluated at the Kansas …

Pursuing The Best Management Strategies For Corn-Soybean Rotation Systems In North Central Kansas, A. A. Correndo, I. A. Ciampitti

Kansas Agricultural Experiment Station Research Reports

The aim of this study was to evaluate different management strategies for improving yield productivity in corn (Zea maysL.) and soybean [Glycine max(L.) Merr.] rotation systems. During the 2018 season, a long-term corn-soybean experiment was continued in Scandia, KS, evaluating five management strategies under rainfed and irrigated conditions. For corn, average yields were 146 bu/a and 172 bu/a under rainfed and irrigated conditions, respectively. For soybean, rainfed and irrigated average seed yields were similar (47–50 bu/a), attributed to herbicide injury on the irrigated plots. For both crop and water scenarios, intensifying the crop management (by modifying …