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What's In The Pan: An Evaluation Of Fragipan Evolution In Western Kentucky, Hannah Leigh Somerville

Theses and Dissertations--Plant and Soil Sciences

The fragipan is a common diagnostic soil feature that does not follow a clear development path. Fragipans are found commonly throughout the southeastern US and cover 2.7 million acres in Kentucky alone. However prevalent, there is no currently accepted genesis theory for fragipans. In this study, we sought to better understand the formation of fragic features in Kentucky’s soils by evaluating fragipan characteristics across a sequence of pedons featuring varying degrees of fragipan development. We found that [Si/Al]_Dithionite, [Si/(Si + Al)]_Dithionite and Si_Dithionite concentration were all higher in well-developed fragipans, suggesting the involvement of an aluminosilicate …

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 …

Optical Seed Sorter-Based Selection Lowers Deoxynivalenol Accumulation In Soft Red Winter Wheat, William Jesse Carmack

Theses and Dissertations--Plant and Soil Sciences

Fusarium head blight (FHB) of wheat (Triticum aestivum L.) results in discolored grain contaminated with deoxynivalenol (DON). DON accumulation, an indicator of FHB resistance, can be quantified and used as the basis for direct phenotypic selection, but testing is expensive. The primary objective of this study was to evaluate an optical seed sorter as an alternative to DON testing for FHB resistance breeding. Three hundred F4 derived soft red winter wheat (SRWW) breeding lines were grown in an inoculated FHB nursery over several years in Lexington, KY. Grain from each breeding line was sorted using an optical seed sorter calibrated …

Understanding The Effects Of Complex Topography On Cover Crop Dynamics And Maize Production In Kentucky Agroecosystems, Samuel John Leuthold

Theses and Dissertations--Plant and Soil Sciences

In Central Kentucky, rolling hill cropland presents a number of challenges related to soil sustainability. Increased topographic complexity can lead to increased erosion, inefficient crop nutrient use and increased nutrient loss. Further, grain crop yields can be variable across both space and time in rolling hill fields and are less resilient to changes in weather conditions than flatter, more homogeneous areas. More than 30% of cropland in Kentucky has a slope greater than 3⁰, which means a large swath of the row crop production land in the state is at increased risk of contribution to soil and water resource degradation. …

Selenium Removal And Pollution Swapping Potentials Of Passive Anaerobic Bioreactors Receiving Coal Slurry Impoundment Wastes, Md Anik Mahmud

Theses and Dissertations--Plant and Soil Sciences

Worldwide, selenium is a major contaminant of concern for coal and metal ore mining industries. In coal mining regions of the eastern USA, for example, billions of liters of wastewaters with elevated Se oxyanion concentrations (primarily SeO₄^2- and SeO₃^2-) are generated during coal washing which is often stored in > 700 man-made impoundments built into remote mountain valleys. Because impoundments are unlined systems, they tend to leak contents into nearby streams, which has detrimental effects on sensitive biota, particularly fish. The primary goal of this project was to evaluate the capacity of passive anaerobic bioreactors (PAB) …

Genomic Selection Strategies To Predict Grain Yield And Disease Resistance Traits In A Wheat Breeding Program, Virginia Laura Verges

Theses and Dissertations--Plant and Soil Sciences

Genomic selection (GS) is a form of marker-assisted selection (MAS) that simultaneously estimates all locus, haplotype or marker effects across the entire genome to calculate genomic estimated breeding values (GEBVs). Since its inception, it has had the attention of breeders keen on finding tools to accelerate genetic gain and reduce phenotyping costs in the breeding program. A first objective of this study was to evaluate strategies to design the training population (TP) and validating population (VP) to estimate GEBVs for grain yield and agronomic traits for wheat breeding lines. Our results demonstrate that, despite the small family size, an approach …

Topographic Gradients In Bulk Soil Properties In Central Kentucky Karst Sinkholes, Anne Kathryn Mcgraw

Theses and Dissertations--Plant and Soil Sciences

The Bluegrass physiographic region of Kentucky is underlain by the late Ordovician Lexington Limestone formation. This area has many identifiable karst features, including sinkholes. Karst sinkholes and associated soils coevolve, which may influence the distribution of bulk soil properties and storage of carbon across karst landscapes. Two sinkholes on the University of Kentucky’s C. Oran Little Animal Research Center in Woodford County, central Kentucky, were selected for analysis. We described and sampled nine pedons at the dominant landscape positions (e.g., summit, shoulder, backslope, footslope, and toeslope) within the two sinkholes; we characterized the physical, chemical, and mineralogical soil properties across …

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 …

Leveraging Chemical And Computational Biology To Probe The Cellulose Synthase Complex, B. Kirtley Amos

Theses and Dissertations--Plant and Soil Sciences

Cellular expansion in plants is a complex process driven by the constraint of internal cellular turgor pressure by an expansible cell wall. The main structural element of the cell wall is cellulose. Cellulose is vital to plant fitness and the protein complex that creates it is an excellent target for small molecule inhibition to create herbicides. In the following thesis many small molecules (SMs) from a diverse library were screened in search of new cellulose biosynthesis inhibitors (CBI). Loss of cellular expansion was the primary phenotype used to search for putative CBIs. As such, this was approached in a forward …

Efficacy And Mechanism Of Acs811 In Tomato Immune Responses, Layne Ellen Harris

Theses and Dissertations--Plant and Soil Sciences

Biologicals are increasingly becoming an important part of sustainable integrated pest management in agricultural crop production and encompass a wide variety of products with varying degrees of efficacy and available research data. As biologicals become more integrated into commercial production systems, it is critical to rigorously evaluate biological product efficacy and mode(s) of action in crops. The better that biologicals are understood in terms of effective application, integration into commercial programs, and their specific mechanisms in crop growth and protection, then the greater the opportunity for increasing yields and food security.

ACS811 is a microbial fermentation-based biological product from Alltech …