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Plant Sciences

University of Kentucky

Theses/Dissertations

Rhizosphere

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Enhancing Agroecosystem Phosphorus Management: Root Phenotyping And Decomposition For Improved Phosphorus Cycling, Rebecca Kay Mcgrail Jan 2021

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 …


Nickel Speciation, Microbial Community Structure, And Chemical Attributes In The Rhizosphere Of Nickel Hyperaccumulating And Non-Accumulating Plants Growing In Serpentine Soils, James W. Morris Jan 2020

Nickel Speciation, Microbial Community Structure, And Chemical Attributes In The Rhizosphere Of Nickel Hyperaccumulating And Non-Accumulating Plants Growing In Serpentine Soils, James W. Morris

Theses and Dissertations--Plant and Soil Sciences

Serpentine soils are formed from weathering of serpentinite, the ultramafic parent material that provides serpentine soils with their unique identity. Weathering of serpentinite results in a plethora of edaphic factors that impose strong selection pressures on plant life, with high magnesium (Mg) to calcium (Ca) ratio, low fertility, and high levels of geologically derived metals such as cobalt (Co), chromium (Cr), and nickel (Ni). Appropriately, plant life on serpentine soils is often specialized, sparse, and endemic which in turn affects the ecosystems that develop on serpentine soils from the landscape scale down to the physiology of their inhabitants. At the …


Unveiling Novel Aspects Of D-Amino Acid Metabolism In The Model Bacterium Pseudomonas Putida Kt2440, Atanas D. Radkov Jan 2015

Unveiling Novel Aspects Of D-Amino Acid Metabolism In The Model Bacterium Pseudomonas Putida Kt2440, Atanas D. Radkov

Theses and Dissertations--Plant and Soil Sciences

D-amino acids (D-AAs) are the α-carbon enantiomers of L-amino acids (L- AAs), the building blocks of proteins in known organisms. It was largely believed that D-AAs are unnatural and must be toxic to most organisms, as they would compete with the L-counterparts for protein synthesis. Recently, new methods have been developed that allow scientists to chromatographically separate the two AA stereoisomers. Since that time, it has been discovered that D-AAs are vital molecules and they have been detected in many organisms. The work of this dissertation focuses on their place in bacterial metabolism. This specific area was selected due to …