Agronomy and Crop Sciences Commons^™

Determining Cluster Thinning And Storage Effects On Fruit Quality And Marketability Attributes Of Arkansas Table Grapes Grown Under High Tunnel Systems., Virginia Beasley

Graduate Theses and Dissertations

Table Grapes (Vitus vinifera) are highly valued horticulture crops world-wide. Often, table grape production in the southern United States is restricted due to climate and pest issues. Viticulture production could be expanded to this region by the use of controlled environment growing systems, such as high tunnels (HT). The objective of this project was to evaluate the effectiveness of HT systems for grape cultivation and compare the effects of different cluster thinning treatments on vines. In this two-year study, the cultivars Faith, Gratitude, Hope, and Jupiter were grown in HT systems and assessed for postharvest qualities at harvest and during …

Use Of Acetolactate Synthase-Inhibiting Herbicides In Inzen Grain Sorghum (Sorghum Bicolor L. Moench Ssp. Bicolor), Hunter Bowman

Graduate Theses and Dissertations

Grain sorghum is typically grown as a rotational crop in Arkansas because of its many benefits, one being the effective control of Palmer amaranth through the use of atrazine. However, limited options exist for postemergence (POST) control of weedy grasses within the crop. Inzen™ grain sorghum is the result of a nicosulfuron resistant weedy sorghum biotype cross-bred with a commercial line of grain sorghum. Inzen™ allows for safe use of over-the-top applications of nicosulfuron within the crop. Nicosulfuron is an acetolactate synthase (ALS)-inhibiting herbicide, which has historically been used in corn for control of weedy grasses. Experiments were conducted in …

Resilience To Large, “Catastrophic” Wildfires In North America's Grassland Biome, Victoria M. Donovan, Dirac Twidwell, Daniel R. Uden, Tsegaye Tadesse, Brian D. Wardlow, Christine H. Bielski, Matthew O. Jones, Brady W. Allred, David E. Naugle, Craig R. Allen

Department of Agronomy and Horticulture: Faculty Publications

Wildfires are ecosystem‐level drivers of structure and function in many vegetated biomes. While numerous studies have emphasized the benefits of fire to ecosystems, large wildfires have also been associated with the loss of ecosystem services and shifts in vegetation abundance. The size and number of wildfires are increasing across a number of regions, and yet the outcomes of large wildfire on vegetation at large‐scales are still largely unknown. We introduce an exhaustive analysis of wildfire‐scale vegetation response to large wildfires across North America's grassland biome. We use 18 years of a newly released vegetation data set combined with 1,390 geospatial …

Control Of Volunteer Corn In Enlist Corn And Economics Of Herbicide Programs For Weed Control In Conventional And Multiple Herbicide-Resistant Soybean Across Nebraska, Adam Michael Striegel

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

With commercialization of multiple herbicide-resistant corn and soybean cultivars, producers have new management options for controlling herbicide-resistant weeds and volunteer corn. Corn-on-corn production systems are common in irrigated fields in southcentral Nebraska which can create issues with volunteer corn management in corn fields. Enlist corn contains a new multiple herbicide-resistant trait providing resistance to 2,4-D choline, glyphosate, and the aryloxyphenoxypropionate (FOPs). Field experiments were conducted in 2018 and 2019 at South Central Agricultural Laboratory near Clay Center, Nebraska with the objective to evaluate ACCase-inhibiting herbicides and herbicide application timing on volunteer corn control, Enlist corn injury, and yield. Glyphosate/glufosinate-resistant corn …

Buffalograss Diversity Assessment, Jesse Collin Marshall

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

Buffalograss [Buchloë dactylodes (Nutt.) Engelm. syn. Bouteloua dactyloides (Nutt.) Columbus] is a low input alternative turfgrass for the Great Plains region. Buffalograss is a dioecious stoloniferous warm season grass with wide variation of valuable traits and is well adapted for use in minimal maintenance landscapes. The obligate outcrossing nature of the species and wide variation of potentially valuable traits make buffalograss a prime candidate for cultivar improvement and genetic study. Limited information is available regarding buffalograss genetics. In effort to expand genetic resources around buffalograss, we developed buffalograss derived simple sequence repeat markers from previously available transcriptomes of buffalograss …

Impact Of Agricultural Land Use On Stream Nitrate, Phosphorus, And Sediment Concentrations At The Watershed And Field Scale, Brittany A. Kirsch

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

Water quality is directly impacted by the landscape through which it travels. As such, land use, including summer annual and winter annual/perennial agriculture, has dramatic influence on the water quality of downstream aquatic and terrestrial ecosystems. I examined the impact of agricultural land use on water quality through two projects, one at a watershed scale and one at a field scale. In my first project, I investigated the impact of agricultural land use and climate on water quality in 13 HUC10 watersheds across Nebraska using public data from US Geological Survey (USGS), US Department of Agriculture National Agricultural Statistics Service …

Comparison Of Soil Sampling Techniques For Alkaline Hydrolyzable-Nitrogen On Clay Soils, Jarom T. Davidson, Trenton L. Roberts, Jarrod T. Hardke, Nathan A. Slaton, Anthony Michael Fulford

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

The Nitrogen-Soil Test for Rice (N-STaR) provides a site-specific N rate recommendation by quantifying alkaline hydrolyzable-N (AH-N). A user-friendly method for obtaining a representative N-STaR soil sample is needed, and this study was designed to evaluate the performance of alternative sampling techniques compared with the Dutch auger (DA). The alternative techniques included a Kleen Hole Spade dry (KHS-D), a KHS lubricated with water (KHS-W), a KHS lubricated with WD-40 (KHS-40), and the N-STaR Bucket and Drill (BD). One soil sample was collected with each sampling technique from four blocks and was repeated across 14 sites. Each sample was analyzed for …

Considerations For Crop Rotation From Alfalfa To Corn, Earl Creech, Matt Yost, Grant Cardon, Corey Ransom, Jason Clark

All Current Publications

The importance of rotating out of a declining alfalfa stand is well established. As the alfalfa stand ages, forage yield and quality decline, while weed, insect, and disease pressures increase. Terminating the stand and growing one or more other crops for several (2–3) years allows a grower to press the reset button on a piece of ground. These years of growing another crop will result in more productive alfalfa when a new stand is planted again.

Reaction Of Tepary Beans To Eight Virulent Races Of The Rust Pathogen That Overcomes All Known Common Bean Rust Resistance Genes, Santos Barrera Lemus, Prabin Tamang, Carlos A. Urrea, Marcial A. Pastor-Corrales

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

Bean rust, caused by Uromyces appendiculatus, is a major disease of common and snap bean (Phaseolus vulgaris) worldwide (Stavely, 1984). Although host resistance is an important component of rust management (Mmbaga et al., 1996), populations of the rust pathogen comprise an extensive and shifting virulence diversity that could render susceptible all known rust resistance genes in common bean. Conversely, it has been suggested that certain tepary bean (Phaseolus acutifolius) accessions are broadly resistant to bean rust (Miklas & Stavely, 1998). The objectives of this study were to verify if tepary beans are resistant to …

Extreme Fire As A Management Tool To Combat Regime Shifts In The Range Of The Endangered American Burying Beetle, Alison K. Ludwig, Daniel R. Uden, Dirac Twidwell

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

This study is focused on the population of federally-endangered American burying beetles in south-central Nebraska. It is focused on changes in land cover over time and at several levels of spatial scale, and how management efforts are impacting both the beetle and a changing landscape. Our findings are applicable to a large portion of the Great Plains, which is undergoing the same shift from grassland to woodland, and to areas where the beetle is still found.

Variance Heterogeneity Genome-Wide Mapping For Cadmium In Bread Wheat Reveals Novel Genomic Loci And Epistatic Interactions, Waseem Hussain, Malachy T. Campbell, Diego Jarquin, Harkamal Walia, Gota Morota

Department of Agronomy and Horticulture: Faculty Publications

Genome-wide association mapping identifies quantitative trait loci (QTL) that influence the mean differences between the marker genotypes for a given trait. While most loci influence the mean value of a trait, certain loci, known as variance heterogeneity QTL (vQTL) determine the variability of the trait instead of the mean trait value (mQTL). In the present study, we performed a variance heterogeneity genome-wide association study (vGWAS) for grain cadmium (Cd) concentration in bread wheat. We used double generalized linear model and hierarchical generalized linear model to identify vQTL associated with grain Cd. We identified novel vQTL regions on chromosomes 2A and …

A Global Perspective On Sustainable Intensification Research, Kenneth Cassman, Patricio Grassini

Department of Agronomy and Horticulture: Faculty Publications

Despite general agreement that meeting food demand without further loss of natural ecosystems requires sustainable intensification, there is little dialogue about the research agenda needed to achieve it. To that end, we evaluate current trajectories towards sustainable intensification, review published research on the topic, identify missing links, and propose a prioritization framework to fill gaps. Although progress towards sustainable intensification is behind schedule, we are optimistic that current trends can get back on course assuming a well-prioritized and adequately funded research portfolio and appropriate policies and institutions to support it.

Herbicide Injury From Dicamba And 2,4-D: How Much Is Too Much In Lettuce?, Xinzheng Chen, Amit J. Jhala, Stevan Z. Knezevic, Samuel E. Wortman

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

Off-target herbicide injury from dicamba and 2,4-D is an increasingly common problem for specialty crop growers in the Midwest United States. Lettuce (Lactuca sativa L.) is a common specialty crops grown in Nebraska, but proximity to corn and soybean production leaves growers vulnerable to crop injury and significant economic loss. The goal of this study was to quantify crop injury and yield loss in greenhouse grown lettuce after exposure to simulated sub-lethal drift rates of 2,4-D and dicamba. Sublethal doses were determined based on a percentage of the maximum labeled rate and ranged from 25% to 0.01%. Tested lettuce …

Skeleton Weed Program Review - A Review Undertaken For The Grains, Seeds And Hay Industry Funding Scheme Management Committee 2020, Department Of Primary Industries And Regional Development, Western Australia

Biosecurity published reports

This review was undertaken in two stages. Stage 1 reviewed the Skeleton Weed Program and the global situation on skeleton weed. Stage 2 involved targeted stakeholder consultation to build on the information identified through Stage 1 and identify perceptions and attitudes amongst the Western Australian grain/seed/hay industry with regard to the Skeleton Weed Program (the program). The results of these two processes were used to formulate the key findings and recommendations by the Review Panel to assist the Grains, Seeds and Hay Industry Funding Scheme (IFS) Management Committee in its decision-making.

Using Hydrogeophysics And Xrf To Produce A High-Resolution 3-Dimensional Soil Cadmium Map For Evaluating Hybrid Wheat Trials, Thierry Bienvenu, Trenton Franz, Nuwan Wijewardane, Yufeng Ge

UCARE: Research Products

Cadmium (Cd) accumulation in wheat decreases germination, growth, grain yield, and in higher concentration leads to adverse effects on human health (Liu et al, 2018). Due to wheat cultivars variation in Cd accumulation, wheat breeders aim to select those at low Cd concentration lines in a field. Hence the need to quantify the concentration of Cd at different parts of a field and visually represent on a high resolution Cd distribution map. Various ways to quantify the concentration of soil Cd exist. However, the cost of equipment required make the process quite expensive and labor intensive. This work studied the …

Spring Meadow Management Practices: What’S A Rancher To Do?, Tara M. Harms, Jerry D. Volesky, Mitchell B. Stephenson

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

Subirrigated meadows are a valuable forage resource to ranching operations in the Nebraska Sandhills, being used for both hay production and livestock grazing.

The water table of these meadows is within one meter of the soil surface during the growing season.

In some years, wet conditions hinder meadow utilization, resulting in a buildup of standing dead and litter plant material which can lower forage production.

Investigate if burning and mowing are effective strategies to remove dead plant material from meadows • Determine if burning or mowing interact with grazing to influence end of season forage production

Burning or mowing effectively …

Benzobicyclon Carryover To Crops In The Mississippi Delta, Jason K. Norsworthy, Mason L. Young

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

One experiment was conducted from 2015 to 2016 on a Calloway and Dewitt silt loam soil near Pine Tree (pH 8.3) and Stuttgart (pH 6.0), Arkansas, respectively. The objective was to evaluate the potential for a benzobicyclon application to carryover from rice and cause damage to corn, cotton, grain sorghum, soybean, and sunflower planted the subsequent year. No injury or stand reduction occurred for any crop after applications of benzobicyclon at 0.22 and 0.44 lb a.i. acre⁻¹ at either location. Grain sorghum had a 29% height reduction at Pine Tree at 12 d after planting (DAP); however, no differences …

Residual Herbicide Concentrations In On-Farm Water Storage–Tailwater Recovery Systems: Preliminary Assessment, Erin M. Grantz, Deborah Leslie, Michele Reba, Cammy Willett

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

On-farm water storage–tailwater recovery systems reduce groundwater usage and intercept agrochemical loads, but pesticide residue dynamics in these systems are not well understood. This study monitored concentrations of seven herbicides in seven northeast Arkansas tailwater recovery systems (April 2017–March 2018). Clomazone, glyphosate, metolachlor, and quinclorac were frequently detected, with minimal detections of 2,4-D, dicamba, and propanil. Concentrations peaked during the growing season (1 Apr.–15 Sept.), reflecting an interaction of application and precipitation. Clomazone, glyphosate, and quinclorac concentrations were greater in ditches (−1, respectively) than in the associated reservoir (−1, respectively), but metolachlor concentrations were not different between structure types (maximum …

Comparison Of Weed Control Technologies For Protoporphyrinogen Oxidase-Resistant Palmer Amaranth, Michael Mckinley Houston, L. Tom Barber, Jason K. Norsworthy, Trenton L. Roberts

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Confirmation of protoporphyrinogen oxidase (PPO)-resistant Palmer amaranth (Amaranthus palmeri S.Watson) in 2015 limited weed control options for soybean [Glycine max (L.) Merr.] producers. With already prevalent 5-enolpyruvyl-shikimate-3-phosphate synthase-, acetolactate synthase-, beta-tubulin-, and very-long-chain fatty acid-resistant Palmer amaranth, there are few remaining effective pre-emergence and postemergence herbicides labeled in soybean. The recent commercialization of soybean varieties resistant to dicamba and 2,4-D give producers effective options to control multiresistant Palmer amaranth. To evaluate new and existing technologies and postemergence herbicide options, two experiments were conducted in 2017. These experiments were conducted in Marion and Crawfordsville, AR, two locations with confirmed …

Influence Of Furrow Tillage And Nitrogen Fertilizer Management On Water Quality And Soil Nitrogen Dynamics In Arkansas Irrigated Cotton, Hunter Wood-Pointfield

Student Theses and Dissertations

Furrow irrigation can increase potential for soil erosion and nutrient losses in agricultural cropping systems. A field experiment to examine furrow tillage and N fertilizer application was conducted in irrigated cotton in northeastern Arkansas. Treatments included a conventional sweep plow or conservation plow to clear water furrows and either a subsurface band of 32% urea ammonium nitrate (UAN) or broadcast urea. Runoff water was collected throughout the experiment at the edge of field, and analyzed for water quality. Soil samples of four depths (0-90 cm) were taken during key crop development stages and analyzed for soil exchangeable N. Soluble nutrients …

Optimum Rates Of Surface-Applied Coal Char Decreased Soil Ammonia Volatilization Loss, Dinesh Panday, Maysoon M. Mikha, Harold P. Collins, Virginia L. Jin, Michael Kaiser, Jennifer Cooper, Arindam Malakar, Bijesh Maharjan

Department of Agronomy and Horticulture: Faculty Publications

Fertilizer N losses from agricultural systems have economic and environmental implications. Soil amendment with high C materials, such as coal char, may mitigate N losses. Char, a coal combustion residue, obtained from a sugar factory in Scottsbluff, NE, contained 29% C by weight. A 30-d laboratory study was conducted to evaluate the effects of char addition on N losses via nitrous oxide (N₂O) emission, ammonia (NH₃) volatilization, and nitrate (NO₃–N) leaching from fertilized loam and sandy loam soils. Char was applied at five different rates (0, 6.7, 10.1, 13.4, and 26.8 Mg C ha …

Using Ndvi To Differentiate Wheat Genotypes Productivity Under Dryland And Irrigated Conditions, Mohammed A. Naser, Raj Khosla, Louis Longchamps, Subash Dahal

Department of Agronomy and Horticulture: Faculty Publications

Crop breeders are looking for tools to facilitate the screening of genotypes in field trials. Remote sensing-based indices such as normalized difference vegetative index (NDVI) are sensitive to biomass and nitrogen (N) variability in crop canopies. The objectives of this study were (i) to determine if proximal sensor-based NDVI readings can differentiate the yield of winter wheat (Triticum aestivum L.) genotypes and (ii) to determine if NDVI readings can be used to classify wheat genotypes into grain yield productivity classes. This study was conducted in northeastern Colorado in 2010 and 2011. The NDVI readings were acquired weekly from March to …

Effect Of Low-Use-Rate Zinc Fertilization On Rice Growth And Grain Yield, Maxwell D. Coffin, Nathan A. Slaton

Crop, Soil and Environmental Sciences Faculty Publications and Presentations

Low-use-rate Zn fertilization methods have been developed and marketed for rice (Oryza sativa L.) fertilization with limited research validating their efficacy. Our research objectives were to evaluate the effect of Zn-seed treatment rate combined with six Zn-fertilization methods on early season canopy coverage, tissue-Zn concentration at the mid-tillering stage, and rice grain yield. The field experiment was conducted on six silt loams and one clay. Rice seed was treated with 0 or 3.3 g Zn kg(-1) as ZnO and combined with no Zn, granular ZnSO4 applied at 11 kg Zn ha(-1) (GRAN), 1.68 kg Zn ha(-1) as MicroEssentials (MESZ), 1.1 …

The State Of Sustainable Agriculture And Agroecology Research And Impacts: A Survey Of U.S. Scientists, Marcia Delonge, Tali Robbins, Andrea Basche, Lindsey Haynes-Maslow

Department of Agronomy and Horticulture: Faculty Publications

A growing body of research suggests that although sustainable agriculture, particularly agroecology, can address challenges such as those related to climate change, ecosystem services, food insecurity, and farmer livelihoods, the transition to such systems remains limited. To gain insight into the state of U.S. sustainable agriculture and agroecology, we developed a 28-question mixed-method survey that was administered to scientists in these fields. Respondents (N=168) represented diverse locations, institutions, and career stages. They offered varied definitions of sustainable agriculture, with 40% considering economic and social well-being to be core components. Respondents identified the amount and duration of public research funding as …

Growing Torula Yeast (Candida Utilis) For Food Grade Fatty Acids, Zachary Christman

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

The focus of this article is the cultivation of a food grade yeast for the production of fatty acids without the restrictions of climate or growing season. Torula yeast (Candida utilis) was selected since it can grow on a wide variety of culture media and has over 60 years of use in the food industry. The fatty acid composition of C. utilis grown on two different media are presented in this article; the first example using completely synthetic media and another using distiller’s vinasse. Also, the effect of different culturing conditions on the percentage of various fatty …

Restoring The Fire–Grazing Interaction Promotes Tree–Grass Coexistence By Controlling Woody Encroachment, Jane F. Capozzelli, James R. Miller, Diane M. Debinski, Walter H. Schacht

Department of Agronomy and Horticulture: Faculty Publications

Woody encroachment can convert grasslands and savannas to shrublands and woodlands, so understanding the processes which regulate woody encroachment is necessary to conserve or restore these ecosystems.We hypothesized that recreating the fire–grazing interaction would limit woody encroachment because focal grazing increases fuel accumulation on unburned areas and increases browsing on emergent woody plants in burned areas. This study was conducted in the Grand River Grasslands of Iowa and Missouri (USA) on 11 sites (15.4–35.0 ha). Each site was assigned to one treatment: patch-burn-graze (n = 4), with spatially discrete prescribed fires and free access by cattle (the fire–grazing interaction); graze-andburn …

Combination Of Biological And Chemical Soil Tests Best Predict Maize Nitrogen Response, M. D. Mcdaniel, Daniel T. Walters, L. G. Bundy, Xiaofei Li, Rhae A. Drijber, John E. Sawyer, Michael J. Castellano, C. A.M. Laboski, Peter C. Scharf

Department of Agronomy and Horticulture: Faculty Publications

Soil tests can help optimize nitrogen (N) fertilizer rates, thereby improving farmer profitability and environmental performance. In US Midwest maize (Zea mays) production, however, most soil N tests have limited accuracy to predict N fertilizer requirements. Here we tested the individual and combined ability of 30 soil tests (12 rapid N extractions, seven biological carbon or N tests, six long-term incubation kinetic parameters, and five other routine soil tests), as well as environmental and management data, to predict maize response to N fertilizer across 56 site-years in the US Midwest. Out of 30 soil tests, and across all …

Soybean Response To Water: Trait Identification And Prediction, Shawn Jenkins

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

The rising demand for soybean [Glycine Max (L.) Merrill] taken in consideration with current climatic trends accentuates the importance of improving soybean seed yield response per unit water (WP). To further our understanding of the quantitative WP trait, a multi-omic approach was implemented for improved trait identification and predictive modeling opportunities. Through the evaluation of two recombinant inbred line populations jointly totaling 439 lines subjected to contrasting irrigation treatments, informative agronomic, phenomic, and genomic associations were identified. Across both populations, relationships were identified between lodging at maturity (r = -0.58, H = 0.86), canopy to air temperature differential …

Enhancing Hybrid Prediction In Pearl Millet Using Genomic And/Or Multi- Environment Phenotypic Information Of Inbreds, Diego Jarquin, Reka Howard, Zhikai Liang, Shashi K. Gupta, James C. Schnable, Jose Crossa

Department of Agronomy and Horticulture: Faculty Publications

Genomic selection (GS) is an emerging methodology that helps select superior lines among experimental cultivars in plant breeding programs. It offers the opportunity to increase the productivity of cultivars by delivering increased genetic gains and reducing the breeding cycles. This methodology requires inexpensive and sufficiently dense marker information to be successful, and with whole genome sequencing, it has become an important tool in many crops. The recent assembly of the pearl millet genome has made it possible to employ GS models to improve the selection procedure in pearl millet breeding programs. Here, three GS models were implemented and compared using …

Long-Term Ecological Research In Southern Brazil Grasslands: Effects Of Grazing Exclusion And Deferred Grazing On Plant And Arthropod Communities, Pedro M.A. Ferreira, Bianca O. Andrade, Luciana R. Podgaiski, Amanda C. Dias, Valerio D. Pillar, Gerhard E. Overbeck, Milton De S. Mendonca Jr., Ilsi I. Boldrini

Department of Agronomy and Horticulture: Faculty Publications

Grazing exclusion may lead to biodiversity loss and homogenization of naturally heterogeneous and species-rich grassland ecosystems, and these effects may cascade to higher trophic levels and ecosystem properties. Although grazing exclusion has been studied elsewhere, the consequences of alleviating the disturbance regime in grassland ecosystems remain unclear. In this paper, we present results of the first five years of an experiment in native grasslands of southern Brazil. Using a randomized block experimental design, we examined the effects of three grazing treatments on plant and arthropod communities: (i) deferred grazing (i.e., intermittent grazing), (ii) grazing exclusion and (iii) a control under …