The objective of this research was to compare the effects of combinations of a wide range of cropping sequences and soil bio-covers on soil organic carbon (SOC) and Heterodera glycines under no-tillage. The experiment used a split-block design with four replications at the Milan (RECM) and Middle TN (MTREC) Research & Education Centers. The whole-block treatment was cropping sequences of corn (Zea mays), soybean (Glycine max), and cotton (Gossypium hirsutum). The split-block was bio-covers of winter wheat (Triticum aestivum), hairy vetch (Vicia villosa), poultry litter, and fallow. Soil samples were taken over four years of experimentation. A novel technique was developed to measure SOC called near infrared reflectance spectroscopy (NIR). Partial least squares regression was used to predict SOC as measured by NIR. Results were compared to assess the reliability of NIR determination of organic carbon. NIR analysis correlated well (r greater than 0.9) with SOC as determined by combustion. NIR was therefore considered sufficiently accurate for quantifying soil organic carbon. Overall, both sites showed a small but consistent loss in carbon over all treatments. The average losses of SOC at the 0-5 cm depth were 1.06 and 1.40 Mg ha-1 at RECM and MTREC, respectively. In the subsurface, mean SOC loss at RECM was 1.43 Mg ha-1. Conversely, the subsurface SOC at MTREC was 3.14 Mg ha-1 higher than preexperiment levels. Crop sequence had a significant effect on change in SOC (P ≤ 0.05) in both surface and subsurface regions at RECM. Sequences with two or more years of cotton tended to lose significantly more (P ≤ 0.05) SOC than those with two or more years of soybean. The poultry litter bio-cover lost less surface SOC (0.58 Mg ha-1) than those under vetch (1.33 Mg ha-1) or fallow (1.8 Mg ha-1). Soybean cyst nematode (SCN) eggs were found in sequences containing no soybean throughout the experiment, indicating survival of over seven years without soybean. Sequences with two or more years of soybean had significantly higher (P ≤ 0.01) SCN egg density than others, with continuous soybean having the greatest egg population density. One year of rotation with a non-host crop typically reduced SCN egg population density by more than 50%.

Known members of the plant SABATH family of methyltransferases (MTs) have important biological functions by methylating hormones, signaling molecules and other metabolites. This dissertation aims to systematically investigate the biochemical and biological functions and evolution of SABATH genes in plants. The genomes of rice and poplar have been fully sequenced, which provides unprecedented opportunities for cross-species comparison of the SABATH family. Using a comparative genomic approach, 41 and 33 SABATH genes were identified in rice and poplar, respectively. The expression of these genes in different tissue was analyzed using RT-PCR approach and some genes highly expressed in multiple tissues were cloned. The cloned cDNAs were expressed in E. coli to produce enzymes. Recombinant proteins were tested with a large number of compounds for MT activities. In poplar, two proteins were determined to have MT activities with indole-3-acetic acid (IAA) and jasmonic acid (JA), respectively. Biochemical and gene expression evidence suggests that poplar IAMT (PtIAMT1) has an important role in poplar development through IAA methylation. Poplar JMT (PtJBMT1) shows high levels of expression at multiple tissues under normal conditions, and the expression of PtJBMT1 was slightly induced by wounding and methyl jasmonate treatment, suggesting it has a role in poplar development and defense. Two SABATH genes, IAMT (OsIAMT1) and BSMT (OsBSMT1), were identified in rice. The high level of OsIAMT1 transcripts in rice roots and panicles implies that OsIAMT1 is involved in root and panicle development. OsBSMT1 has MT activities with both salicylic acid and benzoic acid. The specific induction of OsBSMT1 by herbivory and enhanced emission of methylsalicylate support that it has a specific role in plant response to insects. The evolution of the SABATH gene family was also investigated based on the identified SABATH genes in plants using comparative genomics analysis. Phylogenetic analysis revealed that IAMTs in Arabidopsis, rice and poplar are highly conserved, suggesting IAMTs are evolutionarily ancient. However, SAMTs in these plant species are divergent, indicating it is possible that SAMTs were evolved after the split of these plant lineages.

This study focused on three aspects of plant improvement for insect resistance including: testing of candidate organisms for their production of insecticidal proteins, testing of transgenic plants expressing insect resistance genes, and testing novel systems for the evaluation of insect resistance genes. In the initial part of this study, the candidate fungus Beauveria bassiana was tested for its production of insecticidal proteins through a series of insect bioassays containing fungal protein extracts. These extracts were shown to be orally toxic to Plutella xylostella (diamondback moth) and Spodoptera frugiperda (fall armyworm). Assays involving protease treatments significantly decreased mortality indicating the presence of a protein based oral toxin. The following research tested transgenic tobacco plants expressing proteinase inhibitors from Brassica oleracea (cabbage) and Manduca sexta (tobacco hornworm) on the insect pests Helicoverpa zea (corn earworm) and Heliothis virescens (tobacco budworm). Insects fed transgenic tobacco were able to adapt to the recombinant proteinase inhibitors to varying degrees and resulted in no major impacts on insect growth and development. The last part of this study tested a novel insect resistance gene screening system. Agroinfiltrated tobacco transiently co-expressing genes encoding GFP with either a known insecticidal protein (Bt Cry1Ac) or a candidate gene (Brassica oleracea proteinase inhibitor, BoPI) were fed to larval H. zea. Insects fed the known insecticidal protein experienced high mortality. Insects fed tobacco expressing GFP and BoPI showed significant decreases in growth compared to those fed GFP only tissue. Insects feeding on GFP only tissue showed unexpected increases in growth and development compared to insects fed control tissue. Agroinfiltration coupled with an insect bioassay constitutes an efficient system for the evaluation of candidate insect resistance genes.

A general overview of family Psychodidae is given. Genus Eurygarka Quate is revised to include three species. Genus Gondwanoscurus Jezek is revised to include seven species. The status of genus Stupkaiella Vaillant is revised. Eight new Nearctic species: Eurygarka cyphostylus sp. nov., E. nelderi sp. nov., Stupkaiella lasiostyla sp. nov., S. robinsoni sp. nov., S. capricorna sp. nov., Trichomyia rostrata sp. nov., Australopericoma delta sp. nov., and Threticus thelyceratus sp. nov., and two new Oriental species: Gondwanoscurus cruciferus sp. nov. and G. ornithostylus sp. nov. are described. Two Nearctic species: Eurygarka helicis (Dyar) and Stupkaiella bipunctata (Kincaid), and four Oriental species: Gondwanoscurus ejundicus (Quate), G. eximius (Quate), G. mcclurei (Quate) and G. praecipuus (Quate) are redescribed. A list of species collected during a survey of the Psychodidae of Great Smoky Mountains National Park is given, and a key to the genera of Psychodidae occurring in GSMNP is provided. A classification of psychodid subfamilies based on morphological and molecular evidence is proposed.

This research focused on understanding genetic responses of plants to explosives, which is necessary to produce plants to detect and clean soil and water contaminated with toxic explosive compounds. The first study used microarray technology to reveal transcriptional changes in the model plant Arabidopsis thaliana exposed to the explosive compounds RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine; Royal Demolition Explosive or Research Department Explosive) and TNT (2,4,6-trinitrotoluene). This study yielded a list of genes up- and downregulated by explosive compounds, which can be potentially used for phytoremediation (remediation using plants) or phytosensing (detection using plants) of explosive compounds. The second study presented biotechnology tools to enhance phytosensing that might have application in not only explosives phytosensing but also sensing of other contaminants or important biological agents. This study addressed the problem of low detectable levels of reporter gene signal from a phytosensor and the results suggest the potential use of a site-specific recombination system to amplify the reporter gene signal. The final study addressed microarray data analysis and best practices for statistical analysis of microarray data. Standard parametric approaches for microarray analysis can be very conservative, indicating no unusable information from expensive microarray experiments. A nonparametric method of analysis on a variety of microarray datasets proved to be effective in providing reliable and useful information, when the standard parametric approach used was too conservative.

Rhinocyllus conicus Fröelich and Trichosirocalus horridus (Panzer) were introduced from Europe into North America as biological control agents of the exotic weed species Carduus nutans L. Concern exists over the feeding of these weevils on at least 25 species of native Cirsium thistles. Research was conducted to 1) estimate phenological synchrony of the eight thistle species in Tennessee with R. conicus and T. horridus, 2) investigate naturally-occurring populations of the five native Cirsium thistle species for non-target activity by R. conicus and T. horridus, 3) quantify the impacts to plants of each thistle species to feeding of R. conicus and T. horridus, and 4) identify potential areas of non-target feeding by the weevils using spatial analysis. Phenologies of two native species, C. carolinianum and C. horridulum, are synchronous with R. conicus reproduction, and all eight thistle species are phenologically synchronous with the reproduction of T. horridus. No non-target activity by R. conicus was observed in naturally-occurring populations of Cirsium thistles, but adults of T. horridus were documented for the first time on the native species C. carolinianum, C. horridulum, and C. muticum. In caged plant studies, larvae of R. conicus completed development in heads of C. carolinianum and C. horridulum and reduced seed numbers of both native species. Basal meristems of all eight thistle species exposed to T. horridus were damaged at varying levels in caged plant studies, but no other impacts to plants were observed. Spatial analyses showed associations between Mahalanobis distance values and plant counts of Carduus nutans and Cirsium carolinianum in predicted habitats, and the occurrence of Carduus nutans was associated with the occurrence of both weevil species in these habitats. About 12% of the total study area consisted of habitats where C. nutans and Cirsium carolinianum overlap. The potential exists for these weevils to utilize native Cirsium species found in Tennessee as plant hosts. The spatial model developed during this study not only allows potential monitoring of populations of C. carolinianum to be more targeted, but also may be modified to apply to other systems involving interactions among introduced and native species.

Mesotrione, a carotenoid biosynthesis inhibiting herbicide, was evaluated for its use in turfgrass systems. Experiments were conducted to evaluate smooth crabgrass (Digitaria ischaemum) control with preemergence applications of mesotrione plus prodiamine. Experiments evaluated the influence of application timing on the efficacy of mesotrione plus prodiamine combinations and compared mesotrione plus prodiamine to current preemergence and early-postemergence herbicide treatments used for control of crabgrass. Greenhouse studies were conducted to compare the effects of foliar, soil, and soil plus foliar application of mesotrione on yellow nutsedge (Cyperus esculentus) and large crabgrass (Digitaria sanguinalis). Research was conducted in environmental growth rooms to investigate the effects of light intensity and temperature on perennial ryegrass (Lolium perenne) and large crabgrass carotenoid composition following mesotrione application.

The former Van Deventer garden (1924) in Knoxville, Tennessee is one of the rare masterpieces designed by the landscape artist Jens Jensen (1860-1951), who was a distinctive pioneer in the history of American landscape architecture. Very few of his major works survive in the Midwest which was the center of his career, and his residential designs are especially threatened by urban sprawl and land development in modern society. This historic Knoxville garden has been quietly surviving over 80 years through a few private ownerships, and Jensen’s landscape is slowly diminishing as invasive species are fast to colonize in the native woodland where Jensen saw an abundance of native plants in the early 1920s. The purpose of this research was to document the existing condition of the garden and to assess its historical significance, which can be used for a future nomination to the National Register for Historic Places. There are ten signature design elements that Jensen used in the majority of his work, defined by the Jensen scholar, Robert Grese in his book Jens Jensen: Maker of Natural Parks and Gardens (1992): (1) Use of Native Plants, (2) Spaces, (3) Light and Shadow, (4) Movement, (5) Water, (6) Stonework, (7) Council Ring, (8) Players’ Greens, (9) Formal Gardens, and (10) Time and Change. Data collected from historical research and site survey revealed that seven of his signature design elements are evident in the garden today. From a comparison of an existing plant survey and the original plantings indicated on Jensen’s 1924 design, approximately 90 percent of the plants sited by Jensen on the original 1924 planting design have disappeared. This change in plant palette was expected to happen in Jensen’s intention for the landscape. However, the basic landscape vii features, which have strong historic significance, remain intact with minor deteriorations. Preservation recommendations for this Jensen garden are (1) the preservation treatment option as outlined by the U.S. Secretary of the Interior, (2) eradication of the dominate invasive species, (3) plant pest control, (4) removal of fallen trees and plant debris from the significant landscape features, and (5) an easement option for future land protection.

Athletic field managers often make decisions regarding what turfgrass species and varieties to use from past experiences, or from non-sports turf related research such as the National Turfgrass Evaluation Program results. The wear tolerance of turfgrass varieties varies among species and varieties, which can greatly affect the performance of an athletic field. Mowing can also influence athletic field turf. Therefore advancements in mowing technology were tested to determine the impact of mowing, and mowing plus grooming on wear tolerance. A two-year study was conducted at the University of Tennessee East Tennessee Research and Education Center in Alcoa to test four popular bermudagrass varieties (Cynodon dactylon [L.] Pers. x Cynodon transvaalensis Burt-Davy) commonly used as athletic field turfs in the transition zone. The performance of ‘Tifway’, ‘Patriot’, ‘Mississippi Choice’, and ‘Riviera’ bermudagrass were compared after being subjected to either mowing or mowing plus grooming three times a week, as well as fall overseeding with perennial ryegrass (Lolium perenne L.) .Simulated athletic traffic was applied twice a week to mimic high school football schedules using a Cady traffic simulator. Digital image analysis for each traffic event was used to measure changes in percent green cover, color, and turfgrass quality. Surface hardness values were determined using a Clegg Impact Hammer and total turf cover was measured visually once bermudagrass dormancy occurred. Variety performance differed for each year of the study due to weather conditions. Overseeded and non-overseeded ‘Tifway’ and ‘Riviera’ bermudagrass consistently provided the highest percent green cover, color and quality ratings. However, overseeding bermudagrass improved wear tolerance of all varieties tested. Mowing plus grooming three times a week reduced percent turf cover in 2006 but not 2007, and had no effect on color or quality. Mowing plus grooming increased perennial ryegrass stand density following overseeding by providing better seed to soil contact. ‘Tifway’ and ‘Riviera’ bermudagrass provided the best color.

Liner production is a key segment in the nursery industry. Due to a lack of specific of quality standards by governing industry organizations as well as a lack of general consensus among growers of perceived liner quality, a conjoint analysis study was developed to determine buyer and grower preferences for nursery liner product features during point-of-purchase decisions. The study used a visual survey using six variables (first order lateral roots (FOLR), price, region of production, and height, canopy density and caliper uniformity) with varying levels yielding a 3 x 3 x 3 x 2 x 2 x 2 factorial design. Surveys were administered at tradeshows and events around the southeastern United States. Results indicated that a high FOLR, a uniform canopy density and height were most important to purchasing decisions of nursery liner buyers, while liner price and region of production were found not to be important. From the experimental model, utility values for each product feature were derived and can be inserted into an equation to determine a hypothetical quality rating. Growers can use this formula to determine hypothetical quality ratings for their products and serve as a marketing tool for growers. To determine if the production of premium quality liners is economically feasible and help aid growers to take advantage of niche opportunities we investigated production costs of growing ornamental nursery liners in a USDA Plant Hardiness Zone 6b to 7a nursery. We used three contemporary nursery liner production systems: a fieldgroundbed system, a polyhouse-covered groundbed, and a polyhouse covered container system. We estimated capital requirements, fixed costs and variable costs for each system. We also compared production costs of a deciduous plant, a broadleaf evergreen, and a needle leaf evergreen to allow inferences about the widest variety of nursery liner crops.