Plant Sciences Commons^™

Evaluation Of Winter Cereal Cover Crops Across Nitrogen Management Stragies For No-Till Corn Production, Robert Nalley

Theses and Dissertations--Plant and Soil Sciences

Rye (Secale cereale L.) is the most popular winter cereal cover crop utilized before corn, but wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) may provide a comparable value due to their similar fibrous root systems. Despite the benefits associated with winter cereal cover crops, drawbacks are possible for the subsequent corn crop. A field study was conducted with three site-years in Kentucky to measure the impact of the three winter cereals across nitrogen (N) management strategies. Wheat produced the most biomass compared with barley or rye cover crops. Wheat and rye needed approximately 100 more …

Winter Rye (Secale Cereale L.) Management And Production Profitability In Kentucky, And Heritability Of Sensory Attributes, Elzbieta Szuleta

Theses and Dissertations--Plant and Soil Sciences

Winter rye (Secale cereale L.) is a small grain crop characterized by outstanding tolerance to drought, low temperatures, soil salinity and relatively low nutritional requirements. Rye is widely used as a cover crop, well known for its deep root system and outstanding nitrogen scavenging ability. This crop is widely used as a feed for livestock but also it is beneficial in human nutrition. Because of its versatile use, nutritional benefits and unique aroma and flavor, especially for bread and whiskey, there is an increasing interest in this crop in the United States. Unfortunately, rye grain production in the United …

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 …

Molecular Analysis Of Epigenetic Memory Of Stress Establishment And Long-Term Maintenance In A Perennial Woody Plant, Jia Wen Tan

Theses and Dissertations--Plant and Soil Sciences

Plants adapt to extreme environmental conditions through physiological adaptations, which are usually transient. Recent research has suggested that environmental conditions can activate a memory of stress that can result in a primed response to subsequent stress events. While the effect of priming has been observed in many plants, the underlying mechanisms are puzzling and seldom studied. A large body of research has been developed in the last decade linking response to stress, stress priming, and memory of stress with epigenetic mechanisms. This understanding of plant epigenetics has opened the door to the application of epigenetics to crop improvement, such as …

Building A Kentucky Baguette: Agronomic Traits, Bread Baking Quality Measurements, And Sensory Evaluation Of Modern And Landrace Wheat Cultivars Grown Under Conventional And Organic Nitrogen Management, Bryan Brady

Theses and Dissertations--Plant and Soil Sciences

The demand by artisan bread bakers across the United States for local wheat varieties has increased in recent years. The southeast is traditionally a soft winter wheat (SWW) region, producing low gluten flours more suitable for biscuits and cookies. Recently, hard winter wheat (HWW) varieties have been bred to produce acceptable yields in the high humidity environment of the southeastern United States. Artisan bread bakers in Kentucky would like to create a niche food value chain benefitting farmers, small-scale millers, bakers, consumers, and their local and regional food systems (LRFS). The increased demand and the availability of adapted hard wheat …

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 …

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 …

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 …

Optimizing Nitrogen Management In Winter Wheat Production Systems For Improved Bread Baking Quality, Ammar Sadiq Mahdi Al Zubade

Theses and Dissertations--Plant and Soil Sciences

In Kentucky, there is growing interest among farmers to produce high protein and strong gluten wheat that is suitable for bread baking to meet the demand of local artisanal bakers. Soft red winter wheat (SRW) is the most commonly wheat grown in the state and throughout the Southeastern US. Flours produced from SRW are relatively low in grain nitrogen (N) due to the region’s moderate winters and warm humid conditions during grain filling. As such, SRW is used in baking products where lower protein flours are preferred, such as cookies, cakes, pastries and crackers. Unlike SRW, hard red winter wheat …

Evaluation Of Corn Agronomic Management Practices Following A Rye Cover Crop, Daniel John Quinn

Theses and Dissertations--Plant and Soil Sciences

Fall implementation of a rye (Secale cereale L.) cover crop (RCC) prior to spring corn (Zea mays L.) planting is a management practice used to improve soil conservation, water quality, and limit herbicide dependence. However, corn growth and yield following a RCC is often reduced due to early-season nitrogen (N) stress and decreased plant emergence, which can limit RCC adoption. The objective(s) of this research were to evaluate corn agronomic management practices (e.g., N and seeding rate management, in-furrow (IF) starter use) following a RCC and determine which management practices can be used to limit corn stress following …

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 …

Enhancing Agroecosystem Phosphorus Management: Root Phenotyping And Decomposition For Improved Phosphorus Cycling, Rebecca Kay Mcgrail

Theses and Dissertations--Plant and Soil Sciences

Plant roots are often overlooked when making nutrient management decisions. Evaluating differences in P acquisition strategies and cycling resulting from years of shoot-specific plant breeding will aid in reducing fertilizer inputs, with the ultimate goal of improving economic sustainability of crop production and preservation of ecosystem services. To achieve this goal, this research screened a diverse panel of winter wheat cultivars that included old and modern, dwarfed and wild type varieties for physical and chemical root phenotypes related to P acquisition. Old cultivars had larger root systems with more roots that grew two times faster than intermediate/modern cultivars. Wild type …

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 …

Effect Of Management Decisions On Corn Yield Productivity And Stability In Environments With Contrasting Water Availability, Juan Ignacio Di Salvo

Theses and Dissertations--Plant and Soil Sciences

Corn (Zea Mays L.) is a grain crop with large productivity, but also elevated evapotranspiration demand, making it highly susceptible to periods of water stress occurring during critical reproductive stages. Environmental conditions in Kentucky make it possible to grow corn under rainfed conditions, but the crop is still likely to experience water stress during some times of the growing season depending on the year and location. There is limited information on the size of the yield gap due to water stress in Kentucky, and the timing and intensity of water deficit.

In addition, evaluating the interactive effects of hybrid …

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 …

Enhanced Efficiency Nitrogen Formulation Effect On Grass-Legume Pasture Productivity, Kathryn Marie Payne

Theses and Dissertations--Plant and Soil Sciences

The use of nitrogen (N) fertilizer is generally restricted on mixed species forage systems due to its stimulatory effect on grasses which increases competition with legume species. Reduced legume growth from this competition can compromise forage nutritive value and prospective yields. The controlled-release nature of several enhanced efficiency fertilizer N products holds the potential to improve legume persistence in mixed species pastures while providing supplemental N required by the grass component. The studies contained in this dissertation evaluated the effect of different enhanced efficiency N formulations (ATU, ESN, methylene urea, SuperU, and a 75% ESN: 25% urea blend) and untreated …

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 …

Optimizing Cover Crop Rotations For Water, Nitrogen And Weed Management, Cintia Soledad Sciarresi

Theses and Dissertations--Plant and Soil Sciences

Winter cover crops grown in rotation with grain crops can be an efficient integrated pest management tool (IPM). However, cover crop biomass production and thus successful provisioning of ecosystem services depend on a timely planting and cover crop establishment after harvest of a cash crop in the fall. One potential management adaptation is the use of short-season soybeans to advance cover crop planting date in the fall. Cover crops planted earlier in the fall may provide a greater percentage of ground cover early in the season because of higher biomass accumulation that may improve weed suppression. However, adapting to short-season …

Field Evaluation Of Tobacco Engineered For High Leaf-Oil Accumulation, James Perry

Theses and Dissertations--Plant and Soil Sciences

The biofuel market is dominated by ethanol and biodiesel derived from cellulosic and lipid-based biomass crops. This is largely due to the relatively low costs and reliability of production. At present, production of non-food plant-derived oils for biofuel production in the U.S. is minimal. A research team from the Commonwealth Scientific and Industrial Research Organization (CSIRO), an independent Australian federal government research institution, has developed an efficient transgenic system to engineer oil production in tobacco leaves. This novel system is comprised of multiple transgenes that direct the endogenous metabolic flux of oil precursors towards triacylglycerol (TAG) production. Additional genes were …

Effect Of Bedding Type And Soil Incorporation On Nitrogen Mineralization Rate Of Broiler Litter Amended Soils, Lydia A. Fitzgerald

Theses and Dissertations--Plant and Soil Sciences

Broiler litter (BL) is a high value manure available to Kentucky crop producers to utilize as a fertilizer. The rate of BL application, timing of application, and method of application are all important factors to take into account when utilizing BL. A laboratory incubation was conducted to observe nitrogen (N) mineralization rates of BL amended soils over time under different conditions. Different application methods, application rates, watering frequencies, and bedding materials were used to determine their influence on N mineralization. Broiler litter applied on the soil surface, at lower rates, at lower watering frequency resulted in lower mineralization rates than …

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 …

Ecophysiological Analysis Of Yield Determination In Soybean Of Different Relative Maturities, Maria Morrogh Bernard

Theses and Dissertations--Plant and Soil Sciences

Soybean yield differences are a combination of the genotype, environmental conditions, and management practices. Understanding how these factors interact through the analysis of the components involved in yield determination, provides a way to increase potential and actual yields in Kentucky.

Two irrigated experiments were conducted to quantify differences in the mechanisms of yield determination across soybean maturity groups (MG) 2 to 5 (Chapter 1), and to quantify management options (seeding rate and choice of MG cultivar) that increase yield potential of double crop soybean systems (Chapter 2).

Results showed that cultivars used different physiological strategies to achieve high yields, but …

Comparison Of Soil-Applied And Postemergence Herbicides With Multiple Sites Of Herbicidal Activity On Two Populations Of Herbicide-Resistant Palmer Amaranth In Kentucky, Nicholas J. Fleitz

Theses and Dissertations--Plant and Soil Sciences

With the introduction of herbicide resistant Palmer amaranth into Kentucky during the past 10 years there has been an increasing concern for effective control measures in grain production. Field trials were performed in 2016 and 2017 near Barlow and Paris, KY to determine efficacy of chemical control programs targeting herbicide resistant Palmer amaranth. Percent visual control, effects on plant density and plant height were measured in 2016 to determine treatment effectiveness. Treatments containing four different sites of herbicide activity achieved an average of 98% control. Treatments containing only 3, 2 or 1 site of activity only achieved 64%, 45% and …

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 …

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 …

Using Exogenous Hormone Application To Suppress Axillary Shoot Development In Tobacco, W. Jesse Carmack

Theses and Dissertations--Plant and Soil Sciences

The variability in the number of basal axillary shoots (ground suckers) among all tobacco (Nicotiana tabacum L.) varieties, has increased since the hydroponic transplant production system became the standard. The larger root ball of hydroponically produced transplants compared to traditionally produced transplants potentially generates a difference in the ratio of auxin (inhibits axillary shoot formation) to cytokinin (promotes lateral branching), that induces basal axillary shoot development. Starting in 2014, studies were conducted to investigate whether the addition of synthetic auxins or cytokinins to hydroponic transplant production could prevent ground sucker formation. Different tobacco cultivars, with high or low ground sucker …

Evaluating Soil Physical And Chemical Properties Following Addition Of Non-Composted Spent Coffee And Tea For Athletic Fields, Shuang Zhou

Theses and Dissertations--Plant and Soil Sciences

Physical and chemical properties of non-composted spent coffee (CF) and tea (T) suggest they may have applications as soil amendments for improving poor soils. Studies were conducted to determine 1) the effect of amendments on grass growth and soil properties, 2) the effect of incorporation versus surface application of amendments on soil properties, and 3) the effect of amendment application frequency on grass growth and soil properties. In the first study, amendments were mixed with sand and planted to bermudagrass. Treatments included CF, T, and peat moss (PM) mixed with sand, and 100% sand as a control. In the second …

Evaluating Nonstructural Carbohydrate Variation Of Cool-Season Grasses Based On Genotype, Management And Environment, Kelly Joan Prince

Theses and Dissertations--Plant and Soil Sciences

Understanding how nonstructural carbohydrates fluctuate in pastures and being able to quantify them is an essential component in successfully managing grazing animals that may require high or low nonstructural carbohydrate diets. The objectives of this study were 1) to evaluate the effects of genotype, management, and environment on water-soluble carbohydrates (WSC) and ethanol-soluble carbohydrates (ESC) in cool-season grass pastures in central Kentucky, and 2) to develop near-infrared reflectance spectroscopy (NIRS) equations to predict WSC and ESC in cool-season grasses. Ten cool-season grass cultivars consisting of Kentucky bluegrass, tall fescue, orchardgrass and perennial ryegrass were sampled in the morning and afternoon …

Impact Of A High Oil And Protein On Agronomic Traits And Overall Seed Composition In Soybean, Maythem Al-Amery

Theses and Dissertations--Plant and Soil Sciences

New soybean lines have been developed with significantly higher oil, protein + oil and higher meal protein. These soybeans contain a VgD1 gene (highly active acyl-CoA:diacylglycerol acyltransferase, DGAT from Vernonia galamensis (VgDGAT1A) produces much higher oil synthesis and accumulation activity in soybean. Soybean with active DGAT from Vernonia galamensis (VgDGAT1A) has active TAG biosynthesis relative to other DGATs including from soybeans and Arabidopsis. DGATs catalyze the final step of TAG synthesis: DAG (diacylglycerol) + acyl-CoA → TAG + CoASH (Coenzyme A is notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in …

Optimization Of Doubled Haploid Production In Burley Tobacco (Nicotiana Tabacum L.), Ezequiel De Oliveira

Theses and Dissertations--Plant and Soil Sciences

Doubled haploidy (DH) is a plant breeding technique that is often utilized by plant breeders to minimize the time required to reach homozygosity in breeding lines. The first objective of this study was to compare two methods of generating DH lines in tobacco (Nicotiana tabacum L.). Inbred burley tobacco varieties TN 90LC and GR 149LC were used to produce both androgenic derived doubled haploids (ADDH) and maternally derived doubled haploids (MDDH). The relative agronomic performance of TN 90LC and GR 149 LC ADDH and MDDH lines was compared when used either as pure-line cultivars or when used for the …