Agronomy and Crop Sciences Commons^™

Msh1-Mediated Non-Genetic Phenotypic Variation In Plants: Prospects For Epigenetic Breeding In Sorghum Bicolor, Dikungwa Ketumile

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

Sorghum is the fifth most important cereal crop grown in the world, and is the primary staple food for many people in developing countries. Like other major crops, its improvement is constrained by depletion of genetic diversity within breeding germplasm. Investigated in this study is the unique creation of non-genetic phenotypic variation through altering MutS Homolog1 (MSH1), a plant-specific gene, and the potential it presents for sorghum improvement. Suppression of MSH1 results in non-genetic developmental reprogramming. The derived MSH1 memory lines, when used in crossing, result in heritable phenotypic variation that enhances plant vigor and agronomic performance. A …

Induction And Suppression Of Antiviral Rna Silencing By Tomato Spotted Wilt Virus, Sergio M. Gabriel Peralta

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

Tomato spotted wilt virus (TSWV) is an emerging pathogen with wide host range and one of the most important viruses of plants. Information regarding processing of negative single stranded RNA viruses such as TSWV in the RNA silencing pathway remains limited. In nature TSWV is only transmitted by thrips as vectors and since infection occurs in both thrips and plants, an experimental system to transmit using thrips and the detection of TSWV were established. In order to understand the processing of TSWV in the RNA silencing pathway, Arabidopsis thaliana as a model plant was used in the genetic analysis against …

The Effect Of Spray Parameters On The Application Of Enlist Duo, Matthew R. Nelson

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

The emergence of new weed control challenges, along with shifts in weed management strategies and cultural practices, has resulted in an increased reliance on chemical weed control in United States (US) cropping systems. As a result, numerous weed species have evolved resistance to herbicides such as glyphosate, thus prompting the development of new weed control systems designed to aid growers in managing resistant weeds. While these new weed control options may give growers additional management options, the high sensitivity of broadleaf crops, fruits, and vegetables to products containing 2,4-D or dicamba increases the potential for herbicide drift resulting from application …

High And Low Yielding Soybean Lines From An Irrigated Selection Environment: Performance Evaluation In Irrigated And Droughted Environments, Jorge E. Perez Arocho

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

Drought is the most significant abiotic stress affecting agricultural production. Improving seed yield under water stress is an important breeding objective. Soybean cultivars that tolerate water stress could help improve and stabilize production in water-stressed environments. “Drought” needs to be defined, because water stress can vary in intensity, timing, and duration. Other factors including ambient temperature, soil texture, depth, and fertility will influence the impact of limited water on crop productivity. This research addresses the impact of water stress on soybeans adapted to the north-central US, where the majority of soils are relatively deep, fertile silt loams or silty clay …

Detecting, Cloning, And Screening For Suppressors Of Rna Silencing In Maize Chlorotic Mottle Virus And Sugarcane Mosaic Virus, Nicole E. Bacheller

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

Maize lethal necrosis disease (MLND) is one of the most important viral diseases of maize. MLND occurs when Maize chlorotic mottle virus (MCMV) co-infects the same plant with one of several potyviruses, including Sugarcane mosaic virus, Wheat streak mosaic virus or Maize dwarf mosaic virus. Originally prevalent in the Midwest and Peru in the 1970s, the disease was called corn lethal necrosis (CLN) and was controlled through breeding and sanitation. Recently, the disease has re-emerged in East Africa and is rapidly spreading and threatening the food sources of subsistence-farming populations. This re-emergence has raised several questions about the unknown …

A Web Based Real Time Nitrogen Leaching Calculator, Saeideh Samani, Babak Samani, Haishun Yang

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

While nitrogen (N) is an essential nutrient for corn, its leaching to ground water is an serious environmental issue and a hazard to public health. N leaching is closely linked to weather factors, especially rainfall. Prediction of N leaching in cropping systems is critical to improvement of crop management and reduction of N leaching. The objective of this project is to develop a web app that predicts in real-time mode N leaching across Nebraska using real-time weather data.

We are in the processing of developing the web app and expect a prototype to be running in 2017 cropping season. Field …

Genomic Regions Involved In Seed Protein, Oil, And Carbohydrate Concentration In Soybean, Samantha J. Mcconaughy

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

Soybeans [Glycine max (L.) Merr.] are processed for their high-quality vegetable oil and protein meal for feed, food, and industrial applications but, because of the high negative correlations between seed protein and oil concentration, it has been difficult to develop soybean lines with concomitant increases in both protein and oil. Previous studies considered only seed protein or oil concentration. This study is unique in that populations were developed using parental lines that differed in their protein, oil, and total carbohydrate concentrations in the mature seed. Two soybean populations were developed using soybean accession PI 547827 with lower total sugars as …

Emergence, Competition, And Management Of Glyphosate-Resistant Common Ragweed (Ambrosia Artemisiifolia L.) In Nebraska Soybean, Ethann R. Barnes

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

Common ragweed (Ambrosia artemisiifolia L.) is a competitive annual broadleaf weed in soybean (Glycine max) production fields throughout North America. The recent confirmation of glyphosate-resistant common ragweed in Nebraska justified the need to assess the emergence pattern and competitive ability of common ragweed in soybean and to evaluate alternative herbicide programs for effective management. The objectives of this research were to: 1) evaluate the effect of tillage and develop a predictive model for the emergence pattern of common ragweed in Nebraska; 2) model the competitive interaction between soybean and common ragweed as influenced by density and irrigation …

Assessing Anther Extrusion And Its Effect On Us Hard Winter Wheat (Triticum Aestivum L.) Hybrid Seed Production, Nicholas Garst

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

The promise of higher grain yields as a result of the development and production of hybrid wheat (Triticum aestivum L.) has not been fully realized primarily due to the high cost of seed production. Anther extrusion is a key trait that improves pollen availability, and thus, is expected to enhance hybrid wheat seed production yields. Hard winter wheat germplasm adapted to the US Great Plains was visually assessed for anther extrusion in the field and greenhouse environments. Significant genotypic differences were detected and high broad-sense heritability was calculated (ranging from 0.62 to 0.85) for anther extrusion in the field. …