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Management And Characterization Of Root-Knot Nematode (Meloidogyne Spp.) In Kentucky High Tunnels, Victoria Bajek

Theses and Dissertations--Plant and Soil Sciences

Kentucky is one of the most active adopters of high tunnels in the United States. Across the state, high tunnel growers have reaped the benefits of greater marketable yields, season extension, and protection from harsh weather. However, the high tunnel environment has increased soil temperatures and intensive crop production which has the potential to encourage root-knot nematode (RKN; Meloidogyne spp.) infestations. The extent and distribution of RKN in Kentucky were previously unknown. Two on-farm trials in infested high tunnels were conducted to determine whether grafting with RKN-resistant tomato rootstock is a viable management strategy. A statewide soil census to determine …

Effects Of Fungicide Programs And Lower Leaf Removal On Wrapper Leaf Production In Connecticut Broadleaf Cigar Wrapper Tobacco, Caleb Haygan Perkins

Theses and Dissertations--Plant and Soil Sciences

In recent years, there has been increased demand for natural leaf cigar wrappers. Kentucky and Tennessee have been of recent interest as a new area for Connecticut Broadleaf production. Initial production experiences have shown that late-season frogeye leaf spot caused by the pathogen Cercospora nicotianae Ellis & Everh. may result in ‘green spot’ in cured leaf and cause a significant problem for producers of Connecticut Broadleaf cigar wrapper tobacco. Field trials were established in 2021 at Princeton, KY and 2022 in Mayfield, KY and Springfield, TN to evaluate effects of fungicide programs and lower leaf removal on wrapper production and …

Comparison Of Botanical Composition Methods And Change Over Time In Kentucky Pastures, Echo Elizabeth Gotsick

Theses and Dissertations--Plant and Soil Sciences

Botanical composition of pastures has been measured with numerous methods over the last century, but there have been limited direct comparisons between methods. The objective of this study was to compare botanical composition methods, to determine the most accurate and efficient method, and to access pasture composition change over time. Six farms with two pastures each were monitored across the state of Kentucky. Sampling occurred fall 2020 through fall 2022, three times a year using the following methods: step point, visual estimation, occupancy grid, and point quadrat (used as a reference method). The occupancy grid showed the highest similarity to …

Evaluation Of Chemical Control Options, Environmental Factors, And Management Practices Associated With Angular Leaf Spot (Pseudomonas Syringae Pv. Tabaci), Andrea Brooke Webb

Theses and Dissertations--Plant and Soil Sciences

Pseudomonas syringae pv. tabaci tox^- is the causal agent of angular leaf spot in dark tobacco. Since 2015, angular leaf spot has become the most significant foliar disease in dark tobacco production in Kentucky and Tennessee. Dark tobacco producers utilize one main tool, streptomycin sulfate, for the management of this bacterial disease. Resistance to streptomycin sulfate in P. syringae pv. tabaci isolates from dark tobacco fields in western Kentucky was first observed in 2015.

Field spray trials were developed to evaluate the efficacy of alternative active ingredients compared to the grower’s standard, streptomycin sulfate. Two separate field trials were …

Improving Baking Quality Of Soft Red Winter Wheat In Kentucky Through Breeding And Sulfur-Nitrogen Fertility Management, Maria Paula Castellari

Theses and Dissertations--Plant and Soil Sciences

Soft Red Winter (SRW) wheat is an important crop grown on about 400,000 acres in Kentucky as a pivotal cash crop in the 3-crops-in-2-years rotation of corn, wheat, and soybean. The humid environment of Kentucky generates a high yielding wheat crop, with low protein concentration and weak gluten strength. This wheat is mainly sold to millers and used by the industry for cakes, pastries, cookies, and crackers. Conversely, there is a rapidly growing interest in identifying other value-added markets for this wheat different to commodity commercialization, such as artisan-baked goods and craft-distilled beverages. Evaluating the quality characteristics of wheat grown …

Manipulating Species Diversity: Environmental Impacts In Row Crop, Livestock, And Grassland Agroecosystems, Alayna A. Jacobs

Theses and Dissertations--Plant and Soil Sciences

The diversity of living species in an agroecosystem affects both natural resources and agricultural production efficiency. The rise of managed plant monocultures has allowed agricultural yields to increase over time. However, simplifying agroecosystems affects the capacity of the system to sustainably provide clean air, water, and productive soils essential for continued food and fiber production. This dissertation manipulates species diversity in row crop and forage agroecosystems prevalent in the Eastern United States and tracks the associated environmental and agricultural production consequences.

In row crop agroecosystems, increasing plant diversity with winter cover crops has been suggested as a strategy to increase …

Remote Sensing For Quantifying C3 And C4 Grass Ratios In Pastures, Jordyn Alyssa Bush

Theses and Dissertations--Plant and Soil Sciences

The following studies investigate the accuracy and practicality of exploiting the color dichotomy present between C₃ and C₄ grass species to estimate their respective proportions from drone or camera captured imagery. Understanding the proportions of C₃ and C₄ grasses in pastures is vital to sound decision making for livestock production. The ability to monitor these proportions remotely will also allow for large scale monitoring as well as detection of changes in botanical composition over time and in response to weather events, management, or climate change. A free green canopy cover (GCC) analyzing software, Canopeo, was used …

Understanding The Cellular And Physiological Mechanisms Of Fertilization And Early-Stage Seed Development, Mohammad Foteh Ali

Theses and Dissertations--Plant and Soil Sciences

Flowering plants have evolved a unique double-fertilization process. Two sperm cells fuse with two female gametophytic cells, the egg and central cells within the ovule, giving rise to the embryo and endosperm, respectively. Sperm cells in flowering plants are nonmotile and delivered in close proximity to the egg and central cells by the pollen tube. Flowering plants have established filamentous actin (F-actin) based sperm nuclear migration system for successful fertilization. Prior to fertilization, the female gamete forms a mesh-like structure of F-actin that shows constant inward movement from the plasma membrane periphery to the center of the cell where the …

Survey Of Herbicide Resistance And Seed Fate Of Italian Ryegrass (Lolium Perenne Ssp. Multiflorum) In Kentucky, Amber Lynn Herman

Theses and Dissertations--Plant and Soil Sciences

Herbicide resistance is not a new problem for farmers in Kentucky, although the identification of herbicide resistant weed species continues to increase. Italian ryegrass (Lolium perenne ssp. multiflorum) is a problematic weed in Kentucky’s soft red winter wheat that has historically been documented as herbicide resistant in isolated locations. A greenhouse herbicide screen was conducted to further understand the level of glyphosate, pinoxaden, and pinoxaden plus fenoxaprop resistance in Kentucky Italian ryegrass populations. The preliminary screen and dose responses indicate there is one Italian ryegrass population resistant to glyphosate and two populations resistant to pinoxaden along with pinoxaden …

An Evaluation Of Eragrostis Tef For Future Cultivar Development, Eric Wayne Luteyn

Theses and Dissertations--Plant and Soil Sciences

The many benefits of utilizing teff (Eragrostis tef) as small grain is well documented in journal publications. Over time the domestication of this species has become essential to the diets of the local population and the livestock living in the African highlands. Current research points to a high diversity of trait characteristics found in many teff populations and the potential utilization of these traits to increase desirable characteristics in both grain and forage varieties. With the overarching goal of adding to what is already known about teff, this study evaluates the different traits that are of interest to …

Building Capacity For Cool Season Vegetable Production In Kentucky: Strengthening Supply Chains Through Crop Model Development And Analysis Of A Farm-To-Institution Market, Chelsea Jo Maupin

Theses and Dissertations--Plant and Soil Sciences

Cool season vegetable crops are suitable for both direct-to-consumer (DTC) and farm-to-institution (FTI) markets in central Kentucky. However, crop planning for predictable harvest is challenging. Seasonality issues can be detrimental to FTI markets wherein institutions require consistent, large volumes of product. This research investigates both production and market aspects of salad crops in central Kentucky, through development of growing degree day (GDD) crop models for loose-leaf lettuce (Latuca sativa), carrots (Daucus carota subsp. sativus), and spinach (Spinacia oleracea), and through a case study analysis for a FTI initiative called the Salad Bar Program. Simple …

Incorporation Of Summer Annual Mixtures Into Grazing Systems In Kentucky, Kelly Marie Mercier

Theses and Dissertations--Plant and Soil Sciences

Utilizing summer annual grass-legume forage mixtures has the potential to improve forage yield and nutritive characteristics, and/or animal performance during times when cool-season pasture growth is limited by high temperatures. Legumes can utilize atmospheric nitrogen, which can increase crude protein and forage digestibility in mixtures. As nitrogen application generally improves both the yield and nutritive characteristics of summer annual forages, but can have a negative effect on legume competitiveness, nitrogen fertilizer recommendations for legume-containing summer annual mixtures are not well established.

Two experiments were conducted to determine the feasibility of utilizing summer annual mixtures in Kentucky, USA. The first experiment …

Improving Kentucky's Winter Wheat And Double Crop Soybean Rotation, Katherine Susan Rod

Theses and Dissertations--Plant and Soil Sciences

The winter wheat double crop soybean rotation is an economically viable rotation for Kentucky farmers. Recent decreases in commodity prices has warranted the need to evaluate intensive management practices that can increase yields and profitability in this crop rotation. There were three goals of this dissertation: 1.) identify management practices that would decrease deoxynivalenol (DON) in harvested wheat grain and increase wheat heading and anthesis uniformity, 2.) evaluate double crop soybean planting timing and identify intensive management practices to increase seed yield, and 3.) determine the profitability of these management options. These studies were conducted in Princeton KY between 2016 …

In Pursuit Of Understanding Barrel Variation: Surveying The Lignocellulose Composition And Content Changes In Quercus Alba Barrel Staves During Cooperage And Bourbon Whiskey Maturation, Jarrad Wade Gollihue

Theses and Dissertations--Plant and Soil Sciences

Bourbon whiskey is a distilled spirit which is a uniquely American with several legal requirements including 1) the major grain in the mash is corn, 2) must be aged in a new charred white oak barrel, and 3) made in the United States of America. Kentucky is the whiskey historical home, producing most of the bourbon in the United States. Interest in whiskey has developed a need to understand more about the underlying chemistry of bourbon. The charred white oak barrel used in bourbon production is of substantial interest because the barrel has been implicated in giving American whiskey its …

Extracting Secondary Metabolites From Bacterial Endophytes To Suppress Or Promote Sweet Sorghum And Weeds, Mohammad R. Alsabri

Theses and Dissertations--Plant and Soil Sciences

Endophytic bacteria are ubiquitous in agricultural settings and have the potential to drastically affect plant growth both positively and negatively. These complex relationships play a key role in plant nutrition and are therefore of great interest to the agricultural community and beyond. With my dissertation work, I have had the opportunity to examine the relationship between endophytic bacteria and plants in various ways. The first part of my dissertation investigated how the microbial diversity found in soil affects the below- and above-ground traits of Sorghum bicolor. In the second section, I focused on a particular strain of bacteria that …

Cover Crops And Cover Crop Mixes: Stratification Of Biological Effects, Landon M. Gibbs

Theses and Dissertations--Plant and Soil Sciences

The potential nutrient cycling benefits from legumes (e.g. N₂-fixation) and the high biomass potential of cereal rye are well known. Further studies are warranted to evaluate bi-culture mixtures and their effects on soil nutrient stratification and microbial enzyme activity because these two properties may be differently expressed (enhanced) by legume/grass mixes. The objectives of this study were: (1) show different cover crops and cover crop mixes containing grasses and legumes differentially stratify carbon and N; (2) show the change in microbial enzyme activity in soils planted with individual cover crops relative to cover crop mixes; 3) determine the …

Arthropod Resistant Tomatoes: Screening Tools, Yield And Nutritional Quality Of Interspecific Hybrids, Mohammad Hasan Salman Ali Dawood

Theses and Dissertations--Plant and Soil Sciences

Tomato (Solanum lycopersicum) is one of the most economically important vegetable crops grown around globe but is a host for numerous pests and pathogens. In the future, tomato breeders will have to focus on increasing fruit quantity and on enhancing pest resistance. Many accessions of the wild relative of tomato, S. habrochaites display high levels of resistance towards arthropods such as spider mites. The presence of the sesquiterpene hydrocarbon, 7-epi-zingiberene, found in S. habrochaites type IV trichomes has been associated with arthropod resistance. However, the presence of other compounds in its trichome secretions may also be related …

Using Biology To Better Inform Marestail [Conyza Canadensis (L.) Cronq.] Management, Ryan James Collins

Theses and Dissertations--Plant and Soil Sciences

The importance of sustainable weed management practices continues to grow as farmers are increasingly faced with herbicide resistant weed populations. Marestail (Conyza canadensis), also known as horseweed, is a problematic weed in soybean cropping systems that has developed resistance to multiple herbicide modes of action. A two year study was conducted in Lexington, KY, examining timing patterns of marestail emergence and different integrated weed management strategies for marestail prior to no-till soybean. Treatments contained fall and spring applied herbicides with different levels of residual activities, cover crops and combinations of the two. Additionally, yields and partial budget net …

Effects Of Abiotic Stresses On Sorbitol And Ribitol Accumulation And Sorbitol Biosynthesis And Metabolism In Tomato [Solanum Lycopersicum L.], Afaf Almaghamsi

Theses and Dissertations--Plant and Soil Sciences

Abiotic stresses are responsible for limiting crop production worldwide. Among diverse abiotic stresses, drought and salinity are the most challenging. Plants under these conditions have diverse strategies for tolerating stress. Osmotic adjustment and osmoprotection occur in plants during salinity and drought stress through accumulation of compatible solutes to a high level without interfering with cellular metabolism. Polyols (sugar alcohols) including sorbitol and ribitol are one such class of compatible solutes. Using plants of wild-type (WT) and three genetically-modified lines of tomato (Solanum lycopersicum cv. ‘Ailsa Craig’), an empty vector line ‘TR22’, and 2 sdh anti-sense lines ‘TR45’, and ‘TR49’ …

Effects Of Potassium Source And Rate On Yield, Quality, And Leaf Chemistry Of Dark And Burley Tobacco, And Residual Effects Of Soil K Levels, Andrea Brooke Keeney

Theses and Dissertations--Plant and Soil Sciences

Field trials were conducted in 2016, 2017 and 2018 with dark fire-cured, dark air-cured, and burley tobacco at Princeton, Murray and Lexington Kentucky. Tobacco variety used in 2016 was a low converter (LC) variety, varieties used in 2017 and 2018 were LC and higher converter (HC) varieties. Potassium sources used at all locations and in all years were potassium sulfate (K₂SO₄) and potassium chloride (KCl). Application rates used at all locations and in all years were 93, 186, 279 kg K ha^-1along with an untreated control that received no potassium. In all trials, tobacco …

Integrating Cover Crops And Herbicides For Horseweed [Conyza Canadensis (L.) Cronq.] Management Prior To Soybean [Glycine Max (L.) Merr.], Austin Sherman

Theses and Dissertations--Plant and Soil Sciences

Horseweed (Conyza canadensis (L.) Cronq.) is prevalent in Kentucky and can be difficult to control. Research has shown multiple weed control methods to be more sustainable than relying on chemical control alone, so the use of multiple methods for horseweed management was examined in this study. The main objective was to determine best practice(s) to reduce horseweed prior to soybean [Glycine max (L.) Merr.]. Treatments included: fall-planted cover crop [CC; cereal rye (Secale cereale L.) or none], fall-applied herbicide (saflufenacil or none), and spring-applied herbicides (dicamba, 2,4-D ester, or none). We hypothesized horseweed densities would be reduced …

Bacterial Inoculants, Endophytic Bacteria And Their Influence On Nicotiana Physiology, Development And Microbiome, Andrea Marisa Sanchez Barrios

Theses and Dissertations--Plant and Soil Sciences

Soil and root microbial communities have been studied for decades, and the incorporation of high-throughput techniques and analysis has allowed the identification of endophytic/non-culturable organisms. This has helped characterize and establish the core microbiome of many model plant species which include underground and aboveground organs. Unfortunately, the information obtained from some of these model plants is not always transferable to other agronomic species. In this project, we decided to study the microbiome of the Nicotiana genus because of its importance in plant physiological and plant-microbe interactions studies. The data obtained was used as baseline information that allowed us to better …

Can Increasing Grass-Fungal Endophyte Symbiotic Diversity Enhance Grassland Ecosystem Functioning?, Mahtaab Bagherzadeh

Theses and Dissertations--Plant and Soil Sciences

The relationship between biodiversity and ecosystem functioning is important in maintaining agroecosystem sustainability. Plant-microbe symbioses, such as exists between the grass tall fescue (Schedonorus arundinaceum) and the asexual fungal endophyte Epichloë coenophiala, can be utilized to enhance agroecosystem functions, such as herbivore resistance. “Novel” E. coenophiala strains that vary in the production of mammal- and insect-toxic compounds have been identified, inserted into tall fescue cultivars, and are planted in pastures globally. Novel fungal endophyte-tall fescue associations may have divergent ecosystem function effects. This study assessed effects of different fescue-endophyte symbiotic combinations on pasture ecosystem function, including aboveground …

Engineering Zinc Oxide Nanoparticles To Be Used As Nanofertilizers, Zeinah Elhaj Baddar

Theses and Dissertations--Plant and Soil Sciences

Zinc deficient soils, or soils with low Zn bioavailability, are widespread, which exacerbates Zn deficiency in human as crops grown on these soils have low Zn content. Often crop yields are also compromised. Fertilizers based on soluble Zn salts often have limited efficacy in such soils. In this research, we evaluate the performance of polymer coated and bare ZnO nanoparticles (NPs) in an attempt to overcome limitations of soluble Zn salts in alkaline soils. We first synthesized 20-30 nm bare ZnO NPs with different surface chemistries to impart colloidal stability to the particles. Bare ZnO were treated in phosphate solution …

Corn Grain Yield Components And Nutrient Accumulation In Response To Nitrogen, Plant Density And Hybrid, Maria Julia Santoro

Theses and Dissertations--Plant and Soil Sciences

Modern maize hybrids exhibit higher yields, increased biomass production, stress tolerance and greater nitrogen (N) use efficiency. Increased biomass accumulation can influence nutrient uptake and lead to increased nutrient removal. Hybrids were tested at seeding rates (SR) of 74000 (low) and 148000 (supraoptimal) plants ha^-1 and at N rates of 0 (deficient) and 390 (non-limiting) kg N ha^-1. Plants were sampled at V7, V14, R3, R5 and R6 and separated into vegetative and reproductive fractions for determination of dry matter and N accumulation. Grain yield was harvested at R6.

The high SR and high N treatment combination …

Chemical Topping Burley Tobacco, Mitchell D. Richmond

Theses and Dissertations--Plant and Soil Sciences

The act of topping tobacco (Nicotiana tabacum L.) involves the removal of the terminal bud or inflorescence of the tobacco plant. This practice ordinarily is accomplished by manually removing the top of each tobacco plant in an entire field which is labor intensive and costly. Chemical topping utilizes sucker control products to inhibit the terminal bud and axillary bud growth without manually removing the top of the tobacco plant. There were several research objectives in order to determine the utility of a chemical topping system: 1) determine if burley tobacco could be chemically topped with currently registered suckercide products …

Measured Soil Hydraulic Properties As Rzwqm2 Input To Simulate Soil Water Dynamics And Crop Evapotranspiration, Saadi Sattar Shahadha

Theses and Dissertations--Plant and Soil Sciences

Agricultural system models integrate many different processes that cannot all be measured in field experiments and help quantify soil water dynamics, crop evapotranspiration, and crop growth with high temporal resolution. Understanding soil water dynamics and crop evapotranspiration is essential to improve agricultural management of field crops. For example, the interaction between nitrogen application rate and water dynamics is not sufficiently understood. In most cases, model simulations deviate from field measurements, especially when model input parameters are indirectly and unspecifically derived. The extent to which measured soil hydraulic property inputs decrease the discrepancy between measured and simulated soil water status is …

Evaluating Hemp (Cannabis Sativa) As A Forage Based On Yield, Nutritive Analysis, And Morphological Composition, Carol Elizabeth Stringer

Theses and Dissertations--Plant and Soil Sciences

This experiment examined the forage potential of hemp (Cannabis sativa) and kenaf (Hibiscus cannabinus). The objectives were to evaluate yield and forage nutritive value (i.e. NDF, ADF, ADL, IVTD, and CP) fluctuations over the course of a growing season based on planting date, morphological composition, and management. Three types of hemp (grain, fiber, and a dual- purpose type) and kenaf were planted on two dates and were sampled approximately every two weeks throughout the growing season at the University of Kentucky (UK) Research Farm in Lexington, KY. Subsamples were separated into morphological components (i.e. leaf, flowers, stem, core fiber, and …

Establishing Growing Degree Day Estimates To Predict Critical Growth Stages In Soft Red Winter Wheat, Ethan J. Snyder

Theses and Dissertations--Plant and Soil Sciences

Predicting developmental growth stages in soft red winter wheat (Triticum aestivum L.) (SRWW) could improve agronomic management in Kentucky. However, predicting SRWW development is complex due to vernalization requirement and photoperiod sensitivity differences of cultivars. The objectives of this study are to (1) determine ability of Kompetitive Allele Specific PCR (KASP) genotyping to predict phenotype; (2) determine the relative vernalization requirement (RVR) of 50 SRWW cultivars in a greenhouse (GH) assay; and (3) measure growing degree-days (GDD) required by cultivars to reach eight growth stages in a field assay. Fifty SRWW cultivars were characterized with 14 KASP markers for …

Characterizing Nitrogen Loss And Greenhouse Gas Flux Across An Intensification Gradient In Diversified Vegetable Systems, Debendra Shrestha

Theses and Dissertations--Plant and Soil Sciences

The area of vegetable production is growing rapidly world-wide, as are efforts to increase production on existing lands in these labor- and input-intensive systems. Yet information on nutrient losses, greenhouse gas emissions, and input efficiency is lacking. Sustainable intensification of these systems requires knowing how to optimize nutrient and water inputs to improve yields while minimizing negative environmental consequences. This work characterizes soil nitrogen (N) dynamics, nitrate (NO₃¯) leaching, greenhouse gas emissions, and crop yield in five diversified vegetable systems spanning a gradient of intensification that is characterized by inputs, tillage and rotational fallow periods. The study systems …