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Anaerobic Soil Disinfestation: Evaluation Of Anaerobic Soil Disinfestation (Asd) For Warm-Season Vegetable Production In Tennessee, David Grant Mccarty

Masters Theses

Anaerobic soil disinfestation (ASD) is a non-chemical, pre-plant soil treatment recently developed for control of pests such as soilborne plant pathogens, plant-parasitic nematodes, and weeds in specialty crop systems. Soil treatment by ASD includes incorporating a labile carbon (C) source, tarping with plastic, and irrigation of the topsoil to saturation to facilitate the development of strongly anaerobic soil conditions driven by soil microbes. Processes occurring during the anaerobic decomposition of the added C source have been reported control plant pests. The goal of this project was to evaluate and adapt the ASD procedure to environmental conditions and production systems in …

Compatibility Of Essential Oils With The Biocontrol Fungus, Beauveria Bassiana, Wanjing Liu

Masters Theses

The tomato seedling damping-off pathogens Rhizoctonia and Pythium have the potential to cause severe loss in the greenhouse and field. Both seed application of Beauveria bassiana and soil amendment with bioactive monarda herbages are sustainable approaches that can play a role in suppressing damping-off of tomato seedlings. The objectives of this research were to determine the compatibility of essential oils and B. bassiana, and to determine the impact of the two when used together as a seed treatment in greenhouse experiments.

Different concentrations of five essential oils that were active against damping-off pathogens (cymene, carvacrol, thymol, borneol, and geraniol) …

Applicability Of Pigment Compounds For Reducing Light Stress In Bentgrass, Gregory Keith Bartley

Masters Theses

Chlorinated copper phthalocyanine (Signature) and pulverized cells of Chlorella vulgaris (Chlorella) were evaluated in a controlled environment for their ability to act as photoprotectants under supraoptimal levels of ultraviolet (UV) and photosynthetically active radiation (PAR) when applied to plant leaves. Plant pigment changes were documented using High Performance Liquid Chromatography following 1 week of exposure to supraoptimal light in two separate experiments incorporating UV (106.6 μmol m-2 s-1) and PAR (760.6 μmol m-2 s-1) over a 12h photoperiod. Supraoptimal levels of UV and PAR light were found to cause significant reductions in Agrostis palustris chlorophyll and carotenoid leaf pigment levels. …

Investigation Of Phytophthora Species: Phytophthora Colocasiae On Taro And Phytophthora Recovered From Streams In Eastern Tennessee, Sandesh Kumar Shrestha

Masters Theses

Oomycetes, also known as water molds, are morphologically similar to fungi. Unlike fungi, they are diploid and more closely related to plants. Several oomycetes are pathogenic to plants as well as aquatic animals. Members of the genus Phytophthora are a threat to many economically important crops and natural forest systems. The research presented in this thesis addresses intraspecific and interspecific variation in natural populations of Phytophthora. Chapter two summarizes genetic diversity and population structure for Phytophthora colocasiae attacking taro in Hawaii, Vietnam and Hainan Island, China based on novel single nucleotide polymorphism (SNP) markers. Phytophthora colocasiae causes Taro Leaf Blight, …

Heritability And Genetic Gain Of Seed Protein, Oil, And Yield Among Ril Of Soybean, Benjamin T. Wiggins

Masters Theses

Soybean is a remarkable crop that is used in many aspects of our everyday lives. The seed protein is used primarily for livestock feed, though it is becoming more available as a meat substitute for human consumption. Soybean oil is used in many products such as plastics, foods, and industrial products. Seed yield is the major trait that is selected for in a breeding program. A population of 239 F₄ derived RIL from the cross of USG 5601T × U99-310255 was used to calculate heritability estimates by parent offspring regression and on an entry mean basis. This population was …

The Epidemiology Of Puccinia Emaculata (Rust) In Switchgrass And Evaluation Of The Mycoparasite Sphaerellopsis Filum As A Potential Biological Control Organism For Switchgrass Rust., Jonathan Allen Black

Masters Theses

Switchgrass (Panicum virgatum L.) is a warm-season, perennial grass, whose native range includes the entire United States and north into Canada, excluding areas along the pacific coast. Recently, symptoms and signs of rust disease (Puccinia emaculata) have been observed on agronomic switchgrass, which include chlorosis of leaf tissue, necrosis, lodging, and plant death.

To evaluate disease progress of switchgrass rust, in four fields, individual leaves of twenty-five switchgrass plants were rated once per week for fifteen weeks over two growing seasons for disease severity. Rust was first observed on Julian day 166 and 152 in 2010 and …

Abiotic And Biotic Stress Tolerance In Wheat: The Role Of Arbuscular Mycorrhizal Fungi, Marei Mahmoud Abdelkarim

Masters Theses

Rhizospheres of crop plants are complexes of chemical and microbial interactions. Many plants produce allelochemicals, substances that inhibit growth of other plants and microorganisms. In previous research, colonization of Echinacea purpurea by beneficial mycorrhizal fungi appeared to alleviate the effects of allelochemicals on the growth and the development of the medicinal herb (Gualandi, 2010). The overall aims of the work reported here were to determine if colonization by arbuscular mycorrhizal fungi (AMF) alters responses of common wheat (Triticum aestivum) to abiotic [allelopathic effects of sorghum (Sorghum bicolor)] and biotic [bird-cherry oat aphid (Rhopalosiphum padi) …

Chemical Responses Of Two Deciduous Trees After 10-Years Of Exposure To Free Air Co2 Enrichment, Keonhee Kim

Masters Theses

Globally, the mean atmospheric carbon dioxide level has risen steadily since pre-industrial times, which is largely attributable to human activities such as increased emissions from fossil fuel burning, and clearing of forests. Numerous research efforts have been made to understand responses of trees in higher atmospheric carbon dioxide levels in short term, small-scale experiments. To overcome the limitations of these experiments and understand the response of trees in a natural environment, the Free Air Carbon dioxide Enrichment (FACE) project was proposed. FACE is a global project that involves experimentally enriching carbon dioxide in the atmosphere of terrestrial ecosystems. The FACE …

Prevalence Of Copper Resistance Among Foliar Bacterial Pathogens Of Tomato In Tennessee, Jonathon Thomas Mixon

Masters Theses

Foliar bacterial diseases are among the most important diseases of tomato. Bacterial spot is caused by four species: Xanthomonas euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri, hereafter referred to as Xanthomonas spp. Bacterial speck is caused by Pseudomonas syringae pv. tomato and bacterial canker is caused by Clavibacter michiganensis subsp. michiganensis. Fixed copper products are relied upon extensively for control, due to a lack of effective and economical alternatives. Copper resistance in bacterial spot and speck pathogens has been reported worldwide. Copper resistance quite likely exists in Tennessee, but the extent has never been …

Interacting Effects Of Fire Activity, Climate, And Habitat Diversity On Forest Dynamics, El Malpais National Monument, New Mexico, Usa, Alex John Pilote

Masters Theses

The historic effects of fire and climate on stand dynamics in the ponderosa pine-dominated forests of the American Southwest are of increasing concern to land management agencies. Using present forest stand structure, the mixed-conifer forests of the volcanic features in El Malpais National Monument were analyzed at three separate sites: a cinder cone, an ancient basalt flow, and an isolated “island” (kipuka) completely surrounded by basalt flows. Increment cores were collected from 632 trees in 19 plots within the monument to obtain dates of establishment. These dates were compared with historic fire histories and precipitation records to analyze the effects …

Chenopodium Berlandieri And The Cultural Origins Of Agriculture In The Eastern Woodlands, Daniel Shelton Robinson

Masters Theses

The development of agriculture in the New World has been a topic of prominent historic interest, but one that has ignored some regions in favor of others. The woodlands of Eastern North America have felt this bias in the investigation of agricultural origins, but this has not prevented the development of theories to explain the emergence of a complex of indigenous agricultural plants in the region. Data collection and technological advances have in large part validated these theories, creating a model for domestication. By emphasizing farming over other cultural practices, however, these theories lack explanatory power with regards to the …

Detection Of Quantitative Trait Loci For Marker-Assisted Selection Of Soybean Isoflavone Genistein, Christopher Joseph Smallwood

Masters Theses

Soybean [Glycine max (L.) Merrill] is an important crop throughout the world. Among the many seed quality traits contained in soybean are isoflavones, which are associated with numerous health benefits, including cancer prevention, improved cardiovascular health, improved bone health, and reduced menopausal symptoms. This study sought to identify quantitative trait loci (QTL) controlling soybean isoflavones genistein, daidzein, glycitein, and total isoflavone content to gain a better understanding of genetic regions controlling production of these compounds. The phenotypic data for QTL detection was generated in 2009 from a population of 274 recombinant inbred lines (RILs) separated into three field tests …

Cotton (Gossipium Hirsutum L.) Response To Irrigation And Environment In A Short Season Climate, Matthew Scott Wiggins

Masters Theses

Research was conducted in 2010 and 2011 at the West Tennessee Research and Education Center in Jackson, TN to investigate water deficit and irrigation response in cotton to provide a better understanding of physiological growth changes and yield impact on the crop grown in soils of varying depth to a sandy layer. The deep soil yielded more vegetative mass when compared with the shallower soil. This is also true when applying higher rates of irrigation where plants grew two more nodes of growth and 15.2 centimeters of plant height. Time to cotton maturity was delayed seven days in the deep …

Utility Of Aminocyclopyrachlor For Control Of Horsenettle And Tall Ironweed In Cool-Season Grass Pastures, William Paul Phillips

Masters Theses

Previous research has shown that management of horsenettle (Solanum carolinense) and tall ironweed (Vernonia gigantea) in cool-season grass pastures and hayfields is difficult. Therefore, research was conducted at Alcoa, Fork Creek, Greenback, Maynardville, and Pulaski, Tennessee, and at London, Kentucky, in 2010 and 2011 to examine efficacy of aminocyclopyrachlor on these two perennial weeds. Research was conducted on naturally-occurring infestations of each weed. Treatments were: aminocyclopyrachlor (49 g ai/ha) with and without 2,4-D amine (371 g ai/ha), aminocyclopyrachlor (98 g ai/ha) with and without 2,4-D amine (742 g ai/ha), and aminopyralid (88 g ai/ha). Treatments were …

Molecular Marker Assisted Development And Stability Analysis Of Low Phytate, High Inorganic Phosphorus Soybean [Glycine Max (L.) Merrill], Suzannah Joy Wiggins

Masters Theses

Phytate [myo-inositol 1,2,3,4,5,6-hexakisphosphate] is a mixed cation salt of phytic acid which binds to other minerals, in many field crops including soybean [Glycine max (L.) Merr.]. Livestock with monogastric digestive systems lack the ability to break bonds between phytate and these minerals, causing phytate phosphorus (P) to be excreted in the waste and contributing to possible P and other mineral deficiencies. Discovery of single sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers associated with low phytate QTL (cqPha-001 and cqPha-002) have aided in development of low phytate soybean lines. The objectives of this study were …