Agricultural Science Commons^™

Seed Burial Physical Environment Explains Departures From Regional Hydrothermal Model Of Giant Ragweed (Ambrosia Trifida) Seedling Emergence In U.S. Midwest, Adam S. Davis, Sharon Clay, John Cardina, Anita Dille, Frank Forcella, John Lindquist, Christy Sprague

Department of Agronomy and Horticulture: Faculty Publications

Robust predictions of weed seedling emergence from the soil seedbank are needed to aid weed management. A common seed accession (Illinois) of giant ragweed was buried in replicate experimental gardens over 18 site years in Illinois, Michigan, Kansas, Nebraska, Ohio, and South Dakota to examine the importance of site and climate variability by year on seedling emergence. In a nonlinear mixed-effects modeling approach, we used a flexible sigmoidal function (Weibull) to model giant ragweed cumulative seedling emergence in relation to hydrothermal time accumulated in each site-year. An iterative search method across a range of base temperature (T_b) …

Genetic Dissection Of Yield And Its Component Traits Using High-Density Composite Map Of Wheat Chromosome 3a: Bridging Gaps Between Qtls And Underlying Genes, Sachin Rustgi, Mustafa N. Shafqat, Neeraj Kumar, P. Stephen Baenziger, M. Liakat Ali, Ismail M. Dweikat, B. Todd Campbell, Kulvinder Singh Gill

Department of Agronomy and Horticulture: Faculty Publications

Earlier we identified wheat (Triticum aestivum L.) chromosome 3A as a major determinant of grain yield and its component traits. In the present study, a high-density genetic linkage map of 81 chromosome 3A-specific markers was developed to increase the precision of previously identified yield component QTLs, and to map QTLs for biomass-related traits. Many of the previously identified QTLs for yield and its component traits were confirmed and were localized to narrower intervals. Four novel QTLs one each for shoot biomass (Xcfa2262-Xbcd366), total biomass (wPt2740-Xcfa2076), kernels/spike (KPS) (Xwmc664-Xbarc67), and Pseudocercosporella induced lodging ( …

Nitrate Reduction Coupled To Iron(Ii) And Manganese(Ii) Oxidation In An Agricultural Soil, Stephanie Pyzola

Theses and Dissertations--Plant and Soil Sciences

New evidence shows iron(II) oxidation is strongly coupled to nitrate reduction under anaerobic conditions in freshwater sediments and agricultural soils. However, the contribution of iron(II) oxidation to nitrate reduction is unknown. Furthermore, oxidation of manganese(II) by nitrate has been largely overlooked. This study investigated nitrate-dependent iron(II) and manganese(II) oxidation in an agricultural soil (Sadler silt loam) using stirred-batch kinetic techniques with native soil organic carbon (SOC) as the electron donor and included addition of amendments (hydrogen gas and wheat residue). In the presence of native SOC, nitrate-dependent Fe(II) and Mn(II) oxidation occurred at early stages of the reaction while organic …

Ecophysiological Responses Of Tall Fescue Genotypes To Endophyte Infection And Climate Change, Marie Bourguignon

Theses and Dissertations--Plant and Soil Sciences

Tall fescue is a widely used forage grass in the eastern USA and can form a symbiosis with a fungal endophyte, which can be beneficial for the plant but can cause livestock health issues. Little is known regarding the symbiotic response to predicted climate change. To address this knowledge gap, I analyzed tall fescue variety trial data collected throughout the U.S., exploring relationships between climate variables and yield for two different fescue cultivars that were either endophyte-free or infected. This study showed no endophyte or cultivar effect on fescue yield, but identified temperature, precipitation and location as significant predictors of …

Dna Fingerprinting And Anastomosis Grouping Reveal Similar Genetic Diversity In Rhizoctonia Species Infecting Turfgrasses In The Transition Zone Of Usa, B. S. Amaradasa, B. J. Horvath, D. K. Lakshman, S. E. Warnke

Department of Agronomy and Horticulture: Faculty Publications

Rhizoctonia blight is a common and serious disease of many turfgrass species. The most widespread causal agent, Thanatephorus cucumeris (anamorph: R. solani), consists of several genetically different subpopulations. In addition, Waitea circinata varieties zeae, oryzae and circinata (anamorph: Rhizoctonia spp.) also can cause the disease. Accurate identification of the causal pathogen is important for effective management of the disease. It is challenging to distinguish the specific causal pathogen based on disease symptoms or macroscopic and microscopic morphology. Traditional methods such as anastomosis reactions with tester isolates are time consuming and sometimes difficult to interpret. In the present study universally …

Distinguishing Between Yield Advances And Yield Plateaus In Historical Crop Production Trends, Patricio Grassini, Kent M. Eskridge, Kenneth Cassman

Department of Agronomy and Horticulture: Faculty Publications

Food security and land required for food production largely depend on rate of yield gain of major cereal crops. Previous projections of food security are often more optimistic than what historical yield trends would support. Many econometric projections of future food production assume compound rates of yield gain, which are not consistent with historical yield trends. Here we provide a framework to characterize past yield trends and show that linear trajectories adequately describe past yield trends, which means the relative rate of gain decreases over time. Furthermore, there is evidence of yield plateaus or abrupt decreases in rate of yield …

Nitrous Oxide Emissions From Smooth Bromegrass Pasture Under Nitrogen Fertilizer And Ruminant Urine Application In Eastern Nebraska, Laura K. Snell

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

Nitrous oxide (N₂O) is a greenhouse gas primarily produced in soils by denitrifying and nitrifying organisms. Agricultural soils account for 70% of emissions in the United States, but little data is available for contributions from managed pasture ecosystems. This study focused on the production of N₂O in smooth bromegrass (Bromus inermis Leyss.) pastures established on silt loam soils in eastern Nebraska. Thirty smooth bromegrass plots (1.5m x 1.5m) were treated with five different fertilizer treatments (0, 45, 90, 135, and 180 kg N/ha) and two urine treatments (urine and no urine). Herbage sampling was taken …

Marketing Contracts, Overconfidence, And Timing In The Canadian Wheat Market, Fabio L. Mattos, Stefanie A. Fryza

Department of Agronomy and Horticulture: Faculty Publications

This paper investigates factors that impact marketing performance in the Canadian wheat market. Using data provided by the Canadian Wheat Board (CWB) for six crop years, results indicate that producers were not able to profitably use all marketing contracts offered by the CWB, earlier pricing tended to generate better performance, there was a negative relationship between activeness and performance (suggesting overconfidence in marketing skills), and performance was generally worse in volatile crop years. Further analysis reveals some of these findings differ when outperforming and underperforming producers are investigated separately, particularly with respect to activeness and volatility.

Amelioration Of Root Disease Of Subterranean Clover (Trifolium Subterraneum) By Mineral Nutrients, Tim Scanlon, Tiernan A. O’Rourke, Megan H. Ryan, Martin J. Barbetti, Krishnapillai Sivasithamparam

Journal articles

Subterranean clover (Trifolium subterraneum) is a key pasture legume across southern Australia and elsewhere. Decline in subterranean clover pastures was first recognised in Australia during the 1960s and manifests as an increase in weeds and a decrease in desirable legume species. While both root disease and poor nutrition contribute to subterranean clover pasture decline, the relationships between root disease and nutrition have not been determined. The objective of this study was to define these relationships. Field experiments were undertaken to determine the nutritional and pathogen status of soils and subterranean clover from three Western Australian field sites. Subsequently, …

Is Local Food In Your Future?: An Analysis Of The Viability Of The Local Food Movement, Jennifer A. Sliney

Pell Scholars and Senior Theses

The Local Food Movement has arisen in recent decades as a proposed solution to problems in the current food distribution system. Proponents of the movement look to solve problems such as unsustainable farming practices, greenhouse gas emissions, and unhealthy communities. Skeptics raise questions as to whether local food is truly capable of accomplishing any of those. The author proposes that as a solution, aspects of the Local Food Movement such as urban agriculture and attempts at community development should be taken more seriously in order to create a better future for the land and people alike.

Composting Manure And Other Organic Materials, Charles S. Wortmann, Charles A. Shapiro

Department of Agronomy and Horticulture: Faculty Publications

The Composting Process

Composting is the aerobic decomposition of manure or other organic materials in the thermophilic temperature range (104-149oF). Composted material is odorless, fine-textured, and low-moisture. It can be bagged and sold for use in gardens or nurseries, or used as fertilizer on cropland with little odor or fly breeding potential. Composting improves the handling characteristics of any organic residue by reducing its volume and weight. Composting can kill pathogens and weed seeds.

Disadvantages of composting organic residues include loss of nitrogen and other nutrients, time for processing, cost for handling equipment, available land for composting, odors, marketing, diversion …

Escape From Preferential Retention Following Repeated Whole Genome Duplications In Plants, James C. Schnable, Xiaowu Wang, J. Chris Pires, Michael Freeling

Department of Agronomy and Horticulture: Faculty Publications

The well supported gene dosage hypothesis predicts that genes encoding proteins engaged in dose–sensitive interactions cannot be reduced back to single copies once all interacting partners are simultaneously duplicated in a whole genome duplication. The genomes of extant flowering plants are the result of many sequential rounds of whole genome duplication, yet the fraction of genomes devoted to encoding complex molecular machines does not increase as fast as expected through multiple rounds of whole genome duplications. Using parallel interspecies genomic comparisons in the grasses and crucifers, we demonstrate that genes retained as duplicates following a whole genome duplication have only …

Multifunctionality In U.S. Rice Production: A Logit Analysis In Farmers Participation, Juan Tur Cardona

Graduate Theses and Dissertations

Multifunctional agriculture is particularly fundamental to some working lands conservation policies and programs, such as the Environmental Quality Incentive Program (EQIP), Conservation Security Program (CSP) and Wildlife Habitat Incentive Program (WHIP). Farmers can also be engaged in providing recreational and agri-tourism services such as hunting, fishing, bird-watching, farm tours, petting zoos and hospitality services. Using the Agricultural Resource Management Survey (ARMS) we analyze factors associated with participation in conservation, recreation and agri-tourism activities as a function of farm structure, farm financial measures, production practices, and socio-demographic characteristics of the farm operator. To estimate the functional relationships we estimate a binary …

Use Of Cti Grinders For Sorghum Flour Production And Utilization: Final Report, Vilma Ruth Calderón De Zacatares, Lily Marisol López, Kris Emillee Duville, Carla Elizabeth Bermúdez

INTSORMIL Scientific Publications

The use of sorghum for human consumption to add value to the crop and increase its profitability, especially for small and medium producers, has contributed to food security and nutrition in El Salvador. CENTA is promoting the cultivation of sorghum as an alternative to food production in rural and urban areas. Since 2010 when wheat prices lower again, sorghum was no more an alternative to replace wheat in certain types of food, but is being used in more stable markets, as people allergic to gluten, people with diabetes and to correct nutritional deficiencies such as iron deficiency anemia because of …

Strawberry Growth, Yield, Fruit Nutrition, And Control Of Verticillium Wilt With Pre-Plant Soil Fumigants, Ozone, And Biological Control, Justin J. Scurich

Master's Theses

Verticillium wilt is a widespread soilborne disease of strawberry historically controlled by soil fumigation with methyl bromide (MB). MB was banned by the United Nations in 1995 and will be completely phased out by 2015. Research has concentrated on alternative methods of disease control without finding a single alternative able to replace MB in widespread disease control and yield increase. For the current study, strawberries were greenhouse grown in container pots filled with soil from both infested and non-infested areas of a commercial strawberry field in Watsonville, CA. Treatments included pre-plant soil fumigation with commercially available formulations of methyl bromide, …

Proceedings Of The 39th Annual Meeting, Southern Soybean Disease Workers (March 7-8, 2012, Pensacola Beach, Florida), Tom Allen, Boyd Padgett, Danise Beadle, Stephen R. Koenning

Southern Soybean Disease Workers: Conference Proceedings

Contents

Symposium: Soybean Nematodes: Their Status, Impact and Management

The Current Status of Nematodes of Soybean in Louisiana and Arkansas. Charles Overstreet, Edward C McGawley, Melea Martin, and Terry Kirkpatrick

A Molecular Analysis of Resistance of Soybean to the Soybean Cyst Nematode. Vincent Klink

Racism in Nematology. Terry Niblack

SCN-resistant Soybeans, HG types, Yield, and SCN Reproduction: How It All Comes Together in the Field in Iowa. Gregory Tylka

Soybean Lines Evaluated for Resistance to Reniform Nematode. Sally Stetina

Graduate student presentations (Boyd Padgett, moderator)

Fungicide Resistance in Cercospora kikuchii, a Major Pathogen of Louisiana Soybean. Trey Price

Variation …

2011 Vadose Zone Nitrate Study At Hastings, Ne (Revised), Roy F. Spalding, Martin Toavs

Department of Agronomy and Horticulture: Faculty Publications

In an effort to assist Hastings Utilities in the management of their well-head protection area (WHP A) and to protect the groundwater from the impact of nitrate loading from potential nonpoint and point sources, Hastings Utilities subcontracted with the Department of Agronomy and Horticulture at the University of Nebraska for deep vadose zone coring. Continuous 60-ft soil cores were obtained at 36 sites within the apparent WHP A (Figure 1). The sites were selected by Marty Stange on the basis of availability for sampling, management, landuse , cropping history, and location within the WHPA. Nitrogen analyses of these deep soil …

Genome-Wide Analysis Of Syntenic Gene Deletion In The Grasses, James C. Schnable, Michael Freeling, Eric Lyons

Department of Agronomy and Horticulture: Faculty Publications

The grasses, Poaceae, are one of the largest and most successful angiosperm families. Like many radiations of flowering plants, the divergence of the major grass lineages was preceded by a whole-genome duplication (WGD), although these events are not rare for flowering plants. By combining identification of syntenic gene blocks with measures of gene pair divergence and different frequencies of ancient gene loss, we have separated the two subgenomes present in modern grasses. Reciprocal loss of duplicated genes or genomic regions has been hypothesized to reproductively isolate populations and, thus, speciation. However, in contrast to previous studies in yeast and teleost …

Varietal Release History (2006-2012) Of Intsormil-Supported Nars Breeding Programs, Intsormil

INTSORMIL Scientific Publications

Spreadsheet of varietal release history for sorghum and pearl millet, by year, of INTSORMIL-supported national agricultural research systems breeding programs. Includes country, name of variety, on-farm yield, yield of local check variety, amount of seed produced (including breeder and whether Basic/Foundation certified), qualities other than yield (such as drought tolerance, forage quality, food type, etc.), and additional comments, such as whether birds will attack the crop at a particular time during the growing process, etc.

Country data for: Ethiopia, Mali, Mozambique, Niger, Uganda, Zambia, El Salvador, Guatemala, Honduras, and Nicaragua.

Sorgo Sureño Normal: El Sorgo Tradicional De Honduras De Doble Proposito, Alberto Morán Araujo, Miriam Villeda

INTSORMIL Scientific Publications

Origen: En Honduras, el Sorgo Sureño Normal ingresó a la estación experimental La Lujosa, en Choluteca, en el año de 1982, por medio del vivero de resistencia a l a i n t e m p e r i e , d o n d e s e seleccionó por su rendimiento, adaptación y calidad tortillera.

El Sorgo Sureño Normal fue liberado por la Secretaría de Recursos Naturales (SRN) y el Programa Internacional de Sorgo y Mijo (INTSORMIL) en 1985.

Adaptación: Sureño Normal se adapta a climas secos y calientes, suelos pobres, en condiciones de sequía y exceso de humedad …

Igrow Wheat: Best Management Practices For Wheat Production, David C. Clay, C. Gregg Carlson, Kevin Dalsted

Agronomy, Horticulture, and Plant Science Books

No abstract provided.

Brown Midrib2 (Bmr2) Encodes The Major 4-Coumarate: Coenzyme A Ligase Involved In Lignin Biosynthesis In Sorghum (Sorghum Bicolor (L.) Moench), Ana Saballos, Scott Sattler, Emiliano Sanchez, Timothy P. Foster, Zhanguo Xin, Chulhee Kang, Jeffrey F. Pedersen, Wilfred Vermerris

Department of Agronomy and Horticulture: Faculty Publications

Successful modification of plant cell-wall composition without compromising plant integrity is dependent on being able to modify the expression of specific genes, but this can be very challenging when the target genes are members of multigene families. 4-coumarate:CoA ligase (4CL) catalyzes the formation of 4-coumaroyl CoA, a precursor of both flavonoids and monolignols, and is an attractive target for transgenic down-regulation aimed at improving agro-industrial properties. Inconsistent phenotypes of transgenic plants have been attributed to variable levels of down-regulation of multiple 4CL genes. Phylogenetic analysis of the sorghum genome revealed 24 4CL(-like) proteins, five of which cluster with bona fide …

Quantitative Trait Locus Analysis Of Saturated Fatty Acids In A Population Of Recombinant Inbred Lines Of Soybean, Xianzhi Wang, Guo-Liang Jiang, Marci Green, Roy A. Scott, D. L. Hyten, P. B. Cregan

Department of Agronomy and Horticulture: Faculty Publications

Soybean [Glycine max (L.) Merr.] is an important crop which contributes approximately 58% of the world’s oilseed production. Palmitic and stearic acids are the two main saturated fatty acids in soybean oil. Different levels of saturated fatty acids are desired depending on the uses of the soybean oil. Vegetable oil low in saturated fatty acids is preferred for human consumption, while for industrial applications, soybean oil with higher levels of saturated fatty acids is more suitable. The objectives of this study were to identify quantitative trait loci (QTL) for saturated fatty acids, analyze the genetic effects of single QTL …

Natural Variation In Iron Use Efficiency And Mineral Remobilization In Cucumber (Cucumis Sativus), Brian M. Waters, Grace Troupe

Department of Agronomy and Horticulture: Faculty Publications

Aims: Iron (Fe) is an essential micronutrient, and plant-available Fe is often limited in alkaline soils. Fe deficiency chlorosis decreases plant growth and yield. Identification of germplasm with high and low Fe use efficiency will allow studies to better understand the genetic components for breeding Fe efficient varieties.

Methods: A screen using cucumber (Cucumis sativus) seedlings identified varieties that maintained contrasting levels of chlorophyll under Fe deficiency or limitation. A time course of mineral dynamics in cotyledons was conducted.

Results: The variety Ashley had the highest chlorophyll under Fe deficiency and per unit Fe in the leaf, while …

Superweeds And Suspect Seeds: Does The Genetically-Engineered Crop Deregulation Process Put American Agriculture At Risk, Margaret Sova Mccabe

Law Faculty Scholarship

The federal government’s regulatory approach to genetically engineered (GE) crops, known as “The Framework”, is now twenty-five years old. Despite two and half decades of a consistent regulatory regime, GE crop and food regulation remains controversial. This article suggests that regulatory science and its tenets of independence, transparency, and public science should guide reforms of The Framework so that it is an efficient and reliable regulatory system. The article has four parts: 1) it provides a brief overview of the history of GE crop regulation; 2)it describes the key attributes of The Framework and related regulatory documents, with particular focus …

Greenhouse Production Of Strawberries During The Winter, Ellen T. Paparozzi, George E. Meyer, Stacy A. Adams, M. Elizabeth Conley, Benjamin A. Loseke, Paul E. Read

Department of Agronomy and Horticulture: Faculty Publications

Strawberries are one of America’s favorite fruits and are available in grocery stores year round. Given increased shipping and other associated costs as well as the opportunity to provide a fresh, nutritious, local product, our research team is exploring the feasibility of growing strawberries during the winter in Nebraska.

Productivity Of Field Pea (Pisumsativum L.) And Spring Oat (Avena Sativa L.) Grown As Sole And Intercrops Under Different Nitrogen Levels, Chengchou Han, Christopher Borman, Dori Osantowski, Jeremy Wagnitz, Katja Koehler-Cole, Kevin Korus, Evan Sonderegger, Rodrigo Werle, Tara Wood, John L. Lindquist

Department of Agronomy and Horticulture: Faculty Publications

Intercropping cereal grains and legumes has potential as an alternative cool-season forage crop in low-input farming systems. The objectives of this study were to quantify the effects of density, species proportion, and nitrogen (N) supply on the biomass accumulation of field pea and spring oat grown as sole or intercrops. Greenhouse experiments were conducted using an additive series experimental design. Treatments included three fertilizer N rates and 20 density/proportion combinations in a randomized complete block with four replications. Sole plant densities included 2, 3, 4, 5 plants of each species pot-1 (16 cm in diameter, 16 cm in height). The …

Using An Active Optical Sensor To Improve Nitrogen Management In Corn Production, Donato Titolo

Theses and Dissertations--Plant and Soil Sciences

Corn nitrogen (N) applications are still done on a field basis in Kentucky, according to previous crop, soil tillage management and soil drainage. Soil tests, as well as plant analysis for N, are not very useful in making N fertilizer rate recommendations for corn. Recommended rates assume that only 1/3 to 2/3 of applied N is recovered, variability largely due to the strong affect of weather on the release of soil N and fertilizer N fate. Many attempts have been made to apply N in a more precise and efficient way. Two experiments were conducted at Spindeltop, the University of …

Susceptibility Of Cry1ab Maize-Resistant And -Susceptible Strains Of Sugarcane Borer (Lepidoptera: Crambidae) To Four Individual Cry Proteins, Liping Zhang, Fangneng Huang, B. Rogers Leonard, Mao Chen, Thomas Clark, Yu Cheng Zhu, David S. Wangila, Fei Yang, Ying Niu

Department of Entomology: Faculty Publications

Sugarcane borer, Diatraea saccharalis (F.), is a major target of Bt maize in South America and many areas of the US mid-south region. Six laboratory strains of D. saccharalis were established from six single-pair F2 families possessing major resistance alleles to Cry1Ab maize hybrids. Susceptibility of the six strains was evaluated on diet treated with each of four purified trypsin-activated Bt proteins, Cry1Ab, Cry1Aa, Cry1Ac, and Cry1F. Bt susceptibility of the six strains was compared with that of known Cry1Ab-susceptible and -resistant strains of D. saccharalis. At least two of the six strains demonstrated a similar level (>526-fold) …

Inheritance Of Grain Polyphenol Oxidase (Ppo) Activity In Multiple Wheat (Triticum Aestivum L.) Genetic Backgrounds, Somrudee Nilthong, Robert A. Graybosch, P. Stephen Baenziger

Department of Agronomy and Horticulture: Faculty Publications

Grain polyphenol oxidase (PPO) activity can cause discoloration of wheat (Triticum aestivum L.) food products. Five crosses (PI 117635/Antelope; Fielder/ NW03681; Fielder/Antelope; NW07OR1070/Antelope; NW07OR1066/OR2050272H) were selected to study the genetic inheritance of PPO activity. STS markers, PPO18, PPO29 and STS01, were used to identify lines with putative alleles at the Ppo-A1 and Ppo-D1 loci conditioning low or high PPO activity. ANOVA showed significant genotypic effects on PPO activity (P\0.0001) in all populations. The generations and generation 9 genotype effects were not significant in any population. A putative third (null) genotype at Ppo-A1 (no PCR fragments for PPO18) was discovered …