Open Access. Powered by Scholars. Published by Universities.®

Life Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 39

Full-Text Articles in Life Sciences

A Characterization Of Maine Blueberry Growers In 2010, Anya Rose Dec 2010

A Characterization Of Maine Blueberry Growers In 2010, Anya Rose

Electronic Theses and Dissertations

A survey was sent to 343 lowbush blueberry growers in Maine with a response rate of 29%. Growers were asked questions about their management practices, pesticide use, priorities, decision-making influences, and beliefs about pesticide safety. Respondents categorized themselves into one of four categories: Integrated Pest Management (IPM), Conventional, Organic, and No-Spray. Analyses were conducted to examine factors that were linked to these four categories. A major goal of this study was to determine differences and similarities between growers of different management styles, and to define each category by the practices and beliefs of its members. Toxicity ratings were also calculated ...


The Effects Of Living Mulches On Organic, Reduced-Till Broccoli Growth And Management, Sarah Elizabeth Broughton Dec 2010

The Effects Of Living Mulches On Organic, Reduced-Till Broccoli Growth And Management, Sarah Elizabeth Broughton

Masters Theses

Conservation tillage programs have been successfully implemented for many agronomic cropping systems, but adoption of reduced tillage for vegetable crops has been slow. As many conventionally managed conservation tillage programs rely on synthetic herbicides for clean cultivation, alternative methods must be devised to suppress weed pressure and reduce reliance on mechanical cultivation to aid in the development of reduced tillage programs for organic cropping system. Strip tillage is a reduced tillage method that is well suited to vegetable crop production, and the utilization of cover crops and living mulches between rows provides a viable weed management option for organic systems ...


Control Of Glyphosate Resistant Horseweed (Conyza Canadensis) With Saflufenacil And Tank-Mixture Partners., Brock Steven Waggoner Dec 2010

Control Of Glyphosate Resistant Horseweed (Conyza Canadensis) With Saflufenacil And Tank-Mixture Partners., Brock Steven Waggoner

Masters Theses

Field and labratory studies were conducted to determine the efficacy of saflufenacil alone and with mixture partners for burndown. Field studies were conducted in 2009 and 2010 to evaluate saflufenacil in mixtures with glyphosate, glufosinate, or paraquat for control of glyphosate-resistant (GR) horseweed prior to planting cotton. Saflufenacil and saflufenacil mixtures were applied 7 days before planting (DBP). Saflufenacil at 25 and 50 g ai ha-1 in mixture with all three non-selective herbicides provided similar GR horseweed control when compared to the current standard of glyphosate plus dicamba. Control of GR horseweed was also not different at the 25 and ...


Effect Of Mica Content On Surface Infiltration Of Soils In Northwestern Kern County, California, Steven Keyes Stakland Dec 2010

Effect Of Mica Content On Surface Infiltration Of Soils In Northwestern Kern County, California, Steven Keyes Stakland

All Graduate Theses and Dissertations

A soils infiltration rate (IR) is the measured rate that soil is able to absorb water, either from precipitation or irrigation. A low IR can cause damage to crops if the necessary amount of water cannot penetrate to the plant roots in the time needed. The damage can be common in permanent plantings such as almond and pistachio orchards where regular tillage is avoided. This indicates a physical aspect to the problem because tillage increases IR. However, there is also an electrochemical side to infiltration problems because certain calcium surfactant treatments can increase IR. Various other methods have been used ...


Investigating Cold Hardiness And Management Practices Of Warm-Season Putting Green Species In The Transition Zone, John M. Kauffman Aug 2010

Investigating Cold Hardiness And Management Practices Of Warm-Season Putting Green Species In The Transition Zone, John M. Kauffman

Doctoral Dissertations

Warm-season turf species are becoming increasingly popular for putting green use in the transition zone. Ultradwarf bermudagrass (Cynodon dactylon (L.)  C. transvaalensis Burtt-Davy) is the prevalent warm-season putting green species, but seashore paspalum (Paspalum vaginatum Swartz) and ‘Diamond’ zoysiagrass [Zoysia matrella (L.) Merr.] may also be grown in the transition zone. Warm-season species are susceptible to winter injury and may require different management regimes than cool-season species. Therefore, the objectives of this research were to assess the impacts of various management practices on warm-season putting green species and characterize the physiological basis for differences in freeze tolerance of various warm-season ...


Effects Of No-Tillage On Crop Yields And Net Returns Across The United States, Dustin Kevin Toliver Aug 2010

Effects Of No-Tillage On Crop Yields And Net Returns Across The United States, Dustin Kevin Toliver

Masters Theses

Farmers are always looking for ways to increase yields and profits and no-tillage may be a way to achieve this goal. However, a comprehensive study of the performance of no-tillage yields relative to conventional tillage yields and their net returns is lacking. This study evaluated the potential factors that influence differences in conventional tillage and no-tillage yields and net returns as explained by such factors as time, crop, precipitation, soil texture and geographic region. Data were collected from 442 paired tillage experiments growing corn, soybeans, cotton, oats, wheat and sorghum published in three refereed journals. Data were evaluated using a ...


Environmental Variables Influencing The Severity Of Pierce’S Disease In California Grapevines, Christopher James Boisseranc Jun 2010

Environmental Variables Influencing The Severity Of Pierce’S Disease In California Grapevines, Christopher James Boisseranc

Master's Theses and Project Reports

This project was designed to correlate environmental variables with the development of Pierce’s Disease (PD), an infection caused by the gram negative bacterium Xylella fastidiosa (Xf), in grapes (Hopkins et al. 2002). PD is one of the most difficult crop pathogens to manage because it is vectored by insects and its continued presence in the vine is usually fatal. PD is influenced by the interaction of host, disease and vector, and probably many other environmental variables. The general objective was to study and identify the most important variables involved in the expression of Pierce’s Disease.

Over a two ...


Taxonomy, Biogeography And Pest Status Of Marmara Sp. In Northern Mexico And California Citrus Production, Paul Semet Jun 2010

Taxonomy, Biogeography And Pest Status Of Marmara Sp. In Northern Mexico And California Citrus Production, Paul Semet

Master's Theses and Project Reports

A novel lepidopteran sex pheromone lure which was thought to be species-specific to the citrus pest Marmara gulosa (Lepidoptera: Gracillariidae) Guillén (McElfresh et al. 2009) has attracted male moths exhibiting two distinct morphologies. The morphological features examined were the sclerotized parts that make up the male genitalia; which include the valvular lobes, costal lobes, cucullar lobes, and the aedeagus. The sclerotized parts were methodically dissected and mounted on microscope slides. Digital images captured of the slide-mounted specimens proved to be inconsistent with the illustrations provided in the original Marmara gulosa species description (Guillén et al. 2001).

The morphologies of all ...


Influence Of Irrigation Strategies On The Photosynthetic Rate Of Syrah, Daniel Michael Rodrigues Jun 2010

Influence Of Irrigation Strategies On The Photosynthetic Rate Of Syrah, Daniel Michael Rodrigues

Master's Theses and Project Reports

Regulated deficit irrigation (RDI) is a common and useful practice for water conservation and improving grape quality. To attain better grape characteristics and wine quality, a substantial degree of irrigation stress is intentionally allowed to occur during the first part of berry formation and can continue until later into veraison. Understanding the effects of deficit irrigation on photosynthetic rates could be helpful in determining at what degree and duration a grower should perform this irrigation practice. The focus of this study was to determine the effects of using differing degrees of RDI in a vineyard located in Paso Robles, California ...


Classification And Fertility Of Soils In The Big South Fork National River And Recreation Area Based On Landscape Position And Geology, Ryan H. Blair May 2010

Classification And Fertility Of Soils In The Big South Fork National River And Recreation Area Based On Landscape Position And Geology, Ryan H. Blair

Masters Theses

The Big South Fork National River and Recreation Area encompasses more than 50,585 hectares (125,000 acres) of the Cumberland Plateau along the border of Tennessee and Kentucky. Highly dissected and steep terrain have made accessibility to much of the park limited, thus little work has been done to investigate the formation of these soils. Seven native soil profiles were selected for chemical and physical analysis representing Pennsylvanian-aged acidic sandstone and shale geology and landforms. The objectives of this study included the characterization of selected native profiles by physical and chemical analysis, as well as classification using US Soil ...


Lifespan Of Prokaryote Model Organism Escherichia Coli K-12, Hyrum Gillespie May 2010

Lifespan Of Prokaryote Model Organism Escherichia Coli K-12, Hyrum Gillespie

Undergraduate Honors Capstone Projects

Bacteria are amazingly resilient organisms, in that they have evolved and adapted to the many extreme environments of Earth (from salt, to pH, to temperature extremes etc.). The bacterial lifespan and death rates are as important as its growth rates in these extreme environments. Bacteria would be useful to determine the effects of age on single cells, but because bacteria reproduce asexually by binary cell fission (clonal replication), calculating the lifespan has proven elusive. Without the determination of a lifespan, age studies using bacteria have limited application. Further, it has been proposed that organisms whose somatic cell line is not ...


Effects Of Trinexapac-Ethyl And Winter Overseeding On The Morphological Characteristics And Traffic Tolerance Of Bermudagrass Cultivars, William D. Haselbauer May 2010

Effects Of Trinexapac-Ethyl And Winter Overseeding On The Morphological Characteristics And Traffic Tolerance Of Bermudagrass Cultivars, William D. Haselbauer

Masters Theses

Common bermudagrass [Cynodon dactylon (L.) Pers.] and hybrid bermudagrass [C. dactylon (L.) Pers. X C. transvaalensis Burtt-Davy] are some of the most common turfgrasses used on athletic fields. Subsequently, the traffic tolerance of commercially available cultivars and the effects of trinexapac-ethyl (TE) on bermudagrass athletic fields with or without perennial ryegrass are often limited. A two year study at the University of Tennessee was conducted under simulated athletic field traffic to evaluate the performance of bermudagrass cultivars as affected by TE and overseeding. Bermudagrass cultivars evaluated were Tifway, Riviera, Patriot, and Celebration. TE treatments consisted of an untreated control, TE ...


The Influence Of Collective Action And Policy In The Development Of Local Food Systems, Lori Porreca May 2010

The Influence Of Collective Action And Policy In The Development Of Local Food Systems, Lori Porreca

All Graduate Theses and Dissertations

The modern global agrifood system has had significant negative impacts on consumers and producers. This has precipitated the rise of local food systems that are purported to improve the health and livelihoods of consumers and producers. High expectations have led to significant public and private resources dedicated to the development of local food systems. Despite this, there has been little systematic research exploring the social and institutional conditions that facilitate or frustrate local food system development.

Using a comparative case study approach, this study explored the ways local structural conditions, collective action, food system policies, and the political context affect ...


Comparative Performance Of Fluorometry And High Performance Liquid Chromatography In The Detection Of Alfatoxin M1 In Two Commercial Cheeses, Gustavo Pena May 2010

Comparative Performance Of Fluorometry And High Performance Liquid Chromatography In The Detection Of Alfatoxin M1 In Two Commercial Cheeses, Gustavo Pena

All Graduate Theses and Dissertations

Aflatoxin M1 (AFM1) is frequently found in milk and dairy products. It is a metabolite formed in cows from aflatoxin B1 (AFB1), contained in animal feeds. In cheese production AFM1 distributes between curds and whey. In this study, cows were fed 64 µg/AFB1/d for the high treatment, and 5 µg/AFB1/d for the low treatment, to obtain milk contaminated with AFM1 over the 0.5 µg/L and under 0.05 µg/L restrictions, respectively. Cheese was manufactured with milk contaminated with AFM1 at 0.8 and 0.03 ìg/kg by the higher and lower treatment ...


Evapotranspiration Of Kentucky Bluegrass, Lynda L. Fenton May 2010

Evapotranspiration Of Kentucky Bluegrass, Lynda L. Fenton

All Graduate Theses and Dissertations

Rapid population growth in arid regions of the western US is placing increased demand on water resources. Variability in precipitation and common occurrence of drought have promoted scrutiny of water use in urban lawns and gardens. However, few reliable measurements of water use of these landscapes exist. Quantifying the amount of water used vs. required by landscapes such as turfgrass would allow significant water conservation. Evapotranspiration (ET) is affected by biophysical factors such as: available energy, turbulent mixing, saturation deficit, soil water, and stomatal conductance. In order to simulate the water use by turfgrass, the relative importance of these processes ...


Optimizing The Physical And Nutritional Environment Of Unleached Root-Zones, Curtis B. Adams May 2010

Optimizing The Physical And Nutritional Environment Of Unleached Root-Zones, Curtis B. Adams

All Graduate Theses and Dissertations

Unleached root-zones represent an environmental ideal by eliminating wasteful leaching of nutrients and water. NASA grows plants in space in unleached root-zones, incorporating polymer-coated fertilizer (PCF) into a ceramic media (Turface or Profile). However, lack of growth productivity in space has led to the need for research to improve the nutritional and physical environment of the root-zone, which is the objective of this research. PCF types are diverse in release characteristics and the effects of temperature and substrate water content have not been well characterized. In spite of widespread use, studies on chemical properties and applied studies to verify soil ...


Characterization Of Soybean Gmpub1 Proteins That Interact With The Phytophthora Sojae Effector Avr1b Protein, Shan Li Jan 2010

Characterization Of Soybean Gmpub1 Proteins That Interact With The Phytophthora Sojae Effector Avr1b Protein, Shan Li

Graduate Theses and Dissertations

Phytophthora sojae is an oomycete which causes stem and root rot disease in soybean. Upon infection, P. sojae could deliver a series of virulent effector proteins into host cell to promote disease on susceptible plants (Tyler et al. 2008, Gyhre and Robatzek 2008). Avr1b is one such protein (Tyler et al. 2008). In this report, a soybean U-box protein, GmPUB1-1, was isolated by interaction with P. sojae effector Avr1b in yeast. It has a homologous copy which was named GmPUB1-2. These two GmPUB1 proteins share 94% identities. Pull-down assay confirmed the interaction between GmPUB1s and Avr1b in vitro. Mutations in ...


Agronomic And Phenotypic Responses To 75 Years Of Recurrent Selection For Yield In The Iowa Stiff Stalk Synthetic Maize Population, Brent Howard Brekke Jan 2010

Agronomic And Phenotypic Responses To 75 Years Of Recurrent Selection For Yield In The Iowa Stiff Stalk Synthetic Maize Population, Brent Howard Brekke

Graduate Theses and Dissertations

The plant density at which Zea mays L. hybrids achieve maximum grain yield has increased throughout the hybrid era while grain yield on a per plant basis has increased little. Changes in plant traits including grain yield, moisture, test weight, stalk and root lodging, flag leaf angle, anthesis-silking interval(ASI), plant height, tassel branch number, and total number of leaves have been well characterized in comparisons of commercial hybrids representing different eras of hybrid maize production but have yet to be examined in a recurrent selection program.

The objective of this experiment was to determine if direct selection for grain ...


Soybean Seedling Emergence And Yield In The Presence Of Fusarium Virguliforme, Brent James Pacha Jan 2010

Soybean Seedling Emergence And Yield In The Presence Of Fusarium Virguliforme, Brent James Pacha

Graduate Theses and Dissertations

The development of sudden death syndrome (SDS) in Iowa soybean production has progressively increased since being first observed in 1993. Movement of the disease from the Southern United States has brought along with it the agronomic recommendations for management of SDS, however these recommendations have not been investigated in Iowa. This research is part of a number of studies focused on developing agronomic recommendations for the management of SDS in Iowa. The particular studies in this work are focused on the management of the causal organism of SDS Fusarium virguliforme. Chapter two is a literature review of past SDS research ...


Deacclimation Response To Winter Temperature Fluctuations In Lolium Perenne, Jacqueline Farrell Jan 2010

Deacclimation Response To Winter Temperature Fluctuations In Lolium Perenne, Jacqueline Farrell

Graduate Theses and Dissertations

Studies on climate change have shown an increase in not only the average global surface temperature but also an increase in extreme weather events. One such extreme weather event is the occurrence of winter temperature fluctuations, which can induce loss of cold acclimation. Sudden temperature fluctuations have occurred in the United States in the early spring of 2007 and the late winter of 2009. Both events caused significant freezing damage to plants. However, plants that were able to maintain a portion of their original freezing tolerance, by a process called deacclimation resistance, did not suffer significant damage.

Different phenotypic assays ...


Isolation And Characterization Of A Fusarium Virguliforme Toxin That Induces Foliar Sudden Death Syndrome In Soybean [Glycine Max (L.) Merr.], Hargeet Kaur Brar Jan 2010

Isolation And Characterization Of A Fusarium Virguliforme Toxin That Induces Foliar Sudden Death Syndrome In Soybean [Glycine Max (L.) Merr.], Hargeet Kaur Brar

Graduate Theses and Dissertations

Fusarium virguliforme (Fv) is the causal organism of the sudden death syndrome (SDS) in soybean (Glycine max [L.] Merr). The estimated average annual soybean yield loss from this disease is valued at about 300 million dollars. F. virguliforme is a soil borne fungus, which attacks soybean roots and causes root rot as well as chlorosis and necrosis in foliar tissues. The pathogen has never been isolated from the diseased foliar tissues. It was therefore hypothesized that a toxin(s) is involved in the development of the disease.

Cell–free F. virguliforme culture filtrate containing one or more toxins produces foliar ...


Numerical Modeling Of Meteorological And Topographical Effects On Pollen Shed, Dispersion, And Viability, Brian Viner Jan 2010

Numerical Modeling Of Meteorological And Topographical Effects On Pollen Shed, Dispersion, And Viability, Brian Viner

Graduate Theses and Dissertations

For open-pollinated species, the success of a pollen grain pollinating a receptive plant is a function of when it is shed, its dispersion in the atmosphere, and the chance of germination upon deposition. Most studies of pollen dispersion have focused on a source and surrounding fields in relatively flat terrain, but dispersion to distances over 20 km has been reported in regions of complex terrain. For this reason, a more detailed examination of atmospheric dispersion over long distances and the components of dispersion - shed, transport, and successful pollination - was undertaken. This dissertation uses numerical models to predict these components in ...


Evaluation Of An Uncalibrated Agricultural Land Model At The Sub-Field Scale, Jason C. Patton Jan 2010

Evaluation Of An Uncalibrated Agricultural Land Model At The Sub-Field Scale, Jason C. Patton

Graduate Theses and Dissertations

An uncalibrated agricultural land surface model, Agro-IBIS, was validated at the sub-field scale using data collected at a local agricultural field site planted with maize in 2009, with a focus on capturing the spatial variability and accumulation rates of soil moisture and leaf area index. Capturing the variability was deemed important for evaluating the model's potential for inclusion as the land surface model in atmospheric models. An ensemble method of forcing the model with different combinations of input data was used in an attempt to produce the variability seen in measurements across the field. The model was able to ...


Agronomic And Seed Traits Of Soybean Lines With High-Oleate Concentration, Ryan Christopher Brace Jan 2010

Agronomic And Seed Traits Of Soybean Lines With High-Oleate Concentration, Ryan Christopher Brace

Graduate Theses and Dissertations

Soybean [Glycine max (L.) Merr.] oils with high-oleate (HO) or low linolenate (LL) concentrations have greater oxidative stability and longer shelf-life than conventional soybean oil. Soybean lines with the transgenic event DP-305423-1 produce a high-oleate oil and those with the fan1(C1640) and fan3(RG10) alleles produce a low-linolenate oil. The objective of this study was to evaluate the agronomic and seed traits of high-oleate/low-linolenate (HOLL) lines, high-oleate/normal-linolenate (HONL) lines, and normal-oleate/normal-linolenate (NONL) lines selected from four single-cross populations formed by crossing a HOLL parent homozygous for the transgene and the two fan alleles to four conventional ...


Fifty Years Of Agricultural Soil Change In Iowa, Jessica Veenstra Jan 2010

Fifty Years Of Agricultural Soil Change In Iowa, Jessica Veenstra

Graduate Theses and Dissertations

Many scientists have studied agricultural soil change. Most of these studies focus on changes in the surface 0 to 30 cm soil. Despite a whole body of scientific research that shows that soils change on relatively short time scales under different management regimes, classical pedological theory states that we should expect these changes to occur only in the surface few centimeters and that they are not of adequate magnitude to suggest fundamental changes in pedon character over short periods of time. Nevertheless, when we resampled sites that were initially described by the soil survey between 1943 and 1963 and compared ...


Phylloplanins: Novel Antifungal Proteins On Plant Leaf Surfaces, Ryan William Shepherd Jan 2010

Phylloplanins: Novel Antifungal Proteins On Plant Leaf Surfaces, Ryan William Shepherd

University of Kentucky Doctoral Dissertations

Secreted surface proteins are an innate immune defense component employed by animals to inhibit invading microbes. Surface proteins have not been documented in plants, even though the aerial leaf surface, or phylloplane, is a major site of pathogen ingress. We have discovered novel proteins, termed phylloplanins, which accumulate on leaf surfaces of Nicotiana tabacum, and we have isolated the gene Phylloplanin that is unique in gene databases. Natural and E. coli-expressed phylloplanins inhibit spore germination and limit leaf infection by the oomycete pathogen Peronospora tabacina.

We investigated the site of phylloplanin biosynthesis using biochemical techniques. These techniques included radiolabeling ...


Grazing Evaluation Of A Novel Endophyte Tall Fescue Developed For The Upper Transition Zone, Jennifer Michelle Johnson Jan 2010

Grazing Evaluation Of A Novel Endophyte Tall Fescue Developed For The Upper Transition Zone, Jennifer Michelle Johnson

University of Kentucky Doctoral Dissertations

A wild-type endophyte (Neotyphodium coenophialum [(Morgan-Jones & Gams) Glen Bacon & Hanlin]) that infects tall fescue [Lolium arundinaceum (Schreb.) Darbysh. = Schedonorous arundinaceum (Schreb.) Dumort.] imparts tolerances to moisture, heat, and grazing stresses, but also produces ergot alkaloids that adversely affect performance and physiology of cattle. Novel endophytes, developed by AgResearch Ltd. NZ, can sustain fescue persistence and productivity, but do not produce toxic ergot alkaloids. University of Kentucky Plant Breeder, T. D. Phillips Ph.D, developed a tall fescue experimental population (KYFA9301) for the upper transition zone. A 2-yr grazing experiment was conducted with steers to evaluate steer performance and physiology, and ...


Agronomic And Seed Traits Of Soybean Lines With The Rag1 Gene For Aphid Resistance, Justin Lee Mardorf Jan 2010

Agronomic And Seed Traits Of Soybean Lines With The Rag1 Gene For Aphid Resistance, Justin Lee Mardorf

Graduate Theses and Dissertations

Soybean [Glycine max (L.) Merrill] yields can be reduced significantly by infestations of the soybean aphid (Aphis glycines Matsumura). A dominant allele, Rag1, providing resistance to the aphid was identified in PI 548663. The objective of this study was to compare the agronomic and seed traits of 27 BC2F2-derived lines with the Rag1 allele to those of 27 lines with the rag1 allele from the same segregating population. The lines were evaluated under aphid-infested conditions at two Iowa environments in 2008 and under aphid-infested and aphid-free conditions at three Iowa environments during 2009. There were significant differences in mean yield ...


The Agronomic And Economic Performance Of Flax In Iowa, Stefans Robert Gailans Jan 2010

The Agronomic And Economic Performance Of Flax In Iowa, Stefans Robert Gailans

Graduate Theses and Dissertations

Demand for flax (Linum usitatissimum L.) has increased due to the discovered health benefits of adding flaxseed to human diets. A facility in northwest Iowa that processes organic flaxseed for oil provides a viable market for organic growers in the Midwest. Organic growers are particularly concerned about adequate fertility and weed management when adding flax to their crop rotations. Our objective was to evaluate flax response to N rate and source as well as to ambient weed competition when following either soybean or corn in rotation. The particular response variables investigated were seed yield, straw yield, harvest index, oil concentration ...


Soybean Improvement Strategies: Insect-Pollinator Attraction And Genetic Resistance To Whitefly And To Brown Stem Rot, Paola T. Perez Jan 2010

Soybean Improvement Strategies: Insect-Pollinator Attraction And Genetic Resistance To Whitefly And To Brown Stem Rot, Paola T. Perez

Graduate Theses and Dissertations

Soybean [Glycine max (L.) Merr.] is one of the most important plants cultivated worldwide. It is a source of oil and protein and is used for livestock feed, human food, and also for industry. Over the years, yield increases have been accomplished due to genetic improvement and enhancement of agronomic practices. The purpose of this research project was to investigate different strategies for soybean improvement, from genetic resistance to biotic stresses, to surveying perennial wild relatives for insect-pollinator attraction characteristics that could be useful in hybrid seed production in the cultivated species. The first objective of this research was to ...