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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
621

Heat Stress Inhibits Chloroplast Development in Ivy Geranium

Horton, Anna McLaurin 04 May 2018 (has links)
Pelargonium peltatum, ivy geranium, experiences foliar bleaching at temperatures exceeding 30° C. Contessa™ Red (heat tolerant) and Temprano™ Lavender (heat susceptible) were compared. Established plants underwent temperature treatments of 15/20° C or 25/30° C night/day with moisture treatments of 80% or 30% substrate volumetric water content (VWC). Photosynthesis, leaf greenness and growth data were collected at days 0, 7 and 11. No differences in photosynthetic rate nor a decrease in greenness in developed leaves occured in either cultivar due to high temperature or drought. Contessa™ Red had overall greater growth and leaf greenness than Temprano™ Lavender. Greenness and growth increased similarly for both cultivars at 80% VWC. Any decrease in foliar bleaching due to drought was likely due to a decrease in growth. A second study using Temprano™ Lavender indicated foliar bleaching occurs in newly emerging, developing leaves.
622

Multiple Tactics to Improve our Understanding of Soybean Diseases

Mariama Tricuonia Brown (15295693) 14 April 2023 (has links)
<p>  </p> <p>Sudden death syndrome (SDS) caused by <em>Fusarium virguliforme</em> is one of the top yield-reducing diseases of soybean. This disease results in a two-stage symptom development, root rot followed by foliar interveinal chlorosis and necrosis. Foliar symptoms typically appear late in the growing season [full pod to full seed (R4 to R6) reproductive growth stages]. Prior to foliar symptoms, a destructive technique is usually carried out to identify the root rot phase of SDS. This technique requires intensive crop scouting and an expert for accurate diagnosis. Therefore, a nondestructive technique is needed to diagnose SDS disease in the absence of visible foliar symptoms. Additionally, no soybean cultivar is completely resistant to SDS and no single method can completely manage this disease. So, an improved integrated approach is needed for SDS disease management. </p> <p>Foliar fungal diseases such as frogeye leaf spot (<em>Cercospora sojina</em> Hara), Septoria brown spot (<em>Septoria glycines</em> Hemmi), and Cercospora leaf blight (<em>Cercospora</em> spp.) are also economically important diseases of soybean. To limit the losses caused by these diseases, several management methods can be used including the application of foliar fungicide. However, due to the low foliar disease pressure that is observed most years, fungicide applications may not be warranted to be applied annually in Indiana. </p> <p>The objectives of this research were: 1) to assess the effectiveness and economic impact of integrated management strategies that include cultivar selection, seed treatment, and seeding rate on SDS in Indiana; 2) to pre-symptomatically and non-destructively detect SDS disease using hyperspectral measurements; and 3) to evaluate foliar fungicides on soybean foliar diseases and yield in Indiana. </p> <p>Results from this research support the use of a seed treatment to protect soybean roots from SDS infection and the use of a moderately resistant cultivar planted at a seeding rate of 346,535 seeds/ha to protect yield and maximize on net returns. This research also demonstrated the ability of hyperspectral reflectance to discriminate healthy from <em>F. virguliforme</em> infected soybean roots in the absence of foliar symptoms. In addition, results show that fungicide applications can reduce foliar disease over the nontreated control, but under low foliar disease risk, these fungicides did not significantly increase yield over the nontreated control. Altogether, these results will contribute to improved soybean disease management approaches in Indiana.</p>
623

The Effects of Foliar Nutrient Applications on Split, Yield, and Internal Fruit Quality of 'Wonderful' Pomegranate (Punica granatum L.)

Chater, John Matthew 01 December 2015 (has links) (PDF)
Fruit split is the most important physiological disorder in pomegranate production, causing devastating crop losses worldwide. Foliar nutrient applications have been used experimentally to mitigate pomegranate fruit split but none have been conducted using the industry standard cultivar, Wonderful, and little is known about the effects of foliar nutrient applications on pomegranate. Additionally, investigations into putative health benefits of pomegranate fruit have increased interest in its production but limited evidence exists regarding effects of agricultural practices such as foliar fertilizer applications on internal fruit quality. ‘Wonderful’ pomegranate trees at 2 commercial orchards were treated with foliar applications of ZnSO4 (3000 mg∙L-1, 4000 mg∙L-1, or 5000 mg∙L-1), MgSO4 (1%, 2%, or 3%), KNO3 (1%, 2%, or 3%), or deionized (DI) water (control). Fruit were analyzed for fruit split incidence, yield, fruit number per tree, fruit diameter, fruit mass, mass of all arils in fruit, mass of 100 arils, total soluble solids (TSS), titratable acidity (TA), antioxidant activity (AA), total phenolics (TP), and mineral nutrient concentrations of leaves and fruit. Foliar applications of MgSO4 and ZnSO4 resulted in significantly lower fruit split incidence. Treatments had no significant effect on fruit number per tree, fruit diameter, and mass, mass of all arils in fruit, or mass of 100 arils. Leaf N, K, S, Mn, and Zn were significantly affected by the treatments. TSS and TA were not affected significantly by treatments. AA ranged from 77.8-84.3 percent inhibition of 2,2’-diphenyl-1-picrylhydrazyl and TP ranged from 2489-3046 mg·L-1 gallic acid equivalents, with some KNO3 treatments significantly affecting these parameters. Fruit mineral nutrient concentrations were characterized and Zn-treated trees had greater fruit Zn concentrations. The results suggest that foliar ZnSO4 or MgSO4 could be used to decrease fruit split incidence and increase nutritional content of ‘Wonderful’ pomegranate and any of the three tested foliar nutrients could be applied as a foliar fertilizer without negatively impacting fruit yield, size, internal quality, bioactivity, or mineral nutrient concentration.
624

Validation and Optimization of Hyperspectral Reflectance Analysis-Based Predictive Models for the Determination of Plant Functional Traits in Cornus, Rhododendron, and Salix

Valdiviezo, Milton I 01 January 2020 (has links)
Near infrared spectroscopy (NIR) has become increasingly widespread throughout various fields as an alternative method for efficiently phenotyping crops and plants at rates unparalleled by conventional means. With growing reliability, the convergence of NIR spectroscopy and modern machine learning represent a promising methodology offering unprecedented access to rapid, high throughput phenotyping at negligible costs, representing prospects that excite agronomists and plant physiologists alike. However, as is true of all emergent methodologies, progressive refinement towards optimization exposes potential flaws and raises questions, one of which is the cornerstone of this study. Spectroscopic determination of plant functional traits utilizes plants' morphological and biochemical properties to make predictions, and has been validated at the community (inter-family) and individual crop (intraspecific) levels alike, yielding equally reliable predictions at both scales, yet what lies amid these poles on the spectrum of taxonomic scale remains unexplored territory. In this study, we replicated the protocol used in studies of the aforementioned taxonomic scale extremes and applied it to an intermediate scale. Interestingly, we found that predictive models built upon hyperspectral reflectance data collected across three genera of woody plants: Cornus, Rhododendron, and Salix, yielded inconsistent predictions of varying accuracy within and across taxa. Identifying the potential cause(s) underlying variability in predictive power at this intermediate taxonomic scale may reveal novel properties of the methodology, potentially permitting further optimization through careful consideration.
625

Evaluation of Nitrogen Management Schemes in Cover Cropped Vineyards

Moss, James Russell 06 June 2016 (has links)
Vineyards in the Eastern United States are often prone to excessive vegetative growth. In order to suppress excessive vine vigor, many viticulturists have employed cover cropping strategies. Cover crops provide a myriad of agronomic benefits, however they are known to compete with the vine for water and nutrients. Due to the widespread use of cover crops in Eastern vineyards, many vineyards experience nitrogen (N) deficiencies in both the vegetative vine tissue and yeast assimilable nitrogen (YAN) in the juice. Soil applications of calcium nitrate and foliar applications of urea were assessed as a means of vineyard N amelioration at cover cropped sites comprised of Petit Manseng and Sauvignon blanc (Vitis vinifera L.). Perennial White and Crimson clover cover crops and foliar urea applications were also used in a Vidal blanc (Vitis spp.) vineyard. Treatments were imposed in the Sauvignon blanc vineyard for five years. The Petit Manseng and Vidal blanc vineyards were subjected to treatments for two years. Soil-applied N at bloom was most effective at increasing leaf petiole N at véraison, season-long chlorophyll content index (CCI), vine capacity and fruit yield. Fruit yield was increased due to more berries per cluster and greater berry weights. Increased rates of soil-applied N decreased the fruit weight:pruning weight ratio. Foliar-applied N after fruit set was most effective at increasing berry YAN. While most of the measured amino acids in fruit increased in concentration with the application of either soil or foliar N, foliar applications were more effective at increasing fruit amino acids. Clover cover crops offered little to no benefit as a N source in the two-year period of evaluation. None of the N management schemes negatively impacted canopy density, fruit zone light interception, or botrytis bunch rot incidence. The combination of both a soil-applied and foliar-applied N fertilizer may be the most effective means to increase both vine capacity and YAN in vineyards where vineyard floor cover crops are compromising vine N status. / Master of Science
626

Optimizing nitrogen fertilization practices under intensive vineyard cover cropping floor management systems

D'Attilio, DeAnna Rae 28 March 2014 (has links)
Under-trellis cover crops have become more prevalent in East Coast grape growing regions through either intentional planting or adoption of native vegetation, to minimize the potential for erosion and to help regulate grapevine size and vigor. These companion crops, however, have sometimes resulted in increased competition for soil nitrogen, leading to decreased vine nitrogen status and berry yeast assimilable nitrogen (YAN). The aim of this study was to determine the effects of different nitrogen fertilization methods applied at varying doses and different times, on vine and berry nitrogen parameters of cover cropped grapevines. The research described herein involved Sauvignon blanc, Merlot, and Petit Manseng grapevines (Vitis vinifera L.) subjected to different sets of nitrogen treatments, and was primarily conducted over two years. There were very few differences in pruning weights, canopy architecture, components of yield, and primary fruit chemistry amongst nitrogen treatments. Sauvignon blanc petiole nitrogen concentration, season-long chlorophyll content index (CCI) values, and berry YAN were most affected by the highest rate of soil nitrogen treatment (60 kg N/ha total split between two calcium nitrate applications at bloom and six weeks post bloom) and foliar fertilization (40 kg N/ha split over seven to nine urea applications); however, the foliar fertilization was most effective at increasing the concentration of certain individual amino acids. Petit Manseng berry YAN at harvest was increased in response to post-véraison foliar applications (10 kg N/ha split between two urea applications), corresponding to an increased concentration of nine amino acids. Merlot berry YAN, petiole nitrogen concentration, and season-long CCI values were most affected by a high rate of soil nitrogen treatment (60 kg N/ha total split between two calcium nitrate applications at bloom and six weeks post bloom) and establishing clover as the under-trellis cover crop. This study identified nitrogen treatments that improved berry nitrogen concentration and content in cover cropped sites. / Master of Science
627

Lateral Movement of Herbicides on Golf Course Fairways and Effects on Bentgrass Greens

Barker, Whitnee Leigh 25 May 2004 (has links)
Concern has been raised that herbicides recently registered for use in warm-season turf to control perennial ryegrass could be dislodged from treated areas and deposited on neighboring cool-season grasses. In a field study, rimsulfuron was applied at 17.5 or 35 g ai/ha to perennial ryegrass in the afternoon; the following morning while dew was still present, a greens mower was driven through the perennial ryegrass and across adjacent creeping bentgrass. Irrigation had no effect on perennial ryegrass control but reduced visible track length and injury of neighboring creeping bentgrass. When treated perennial ryegrass was not irrigated prior to simulated mowing, tire tracks were evident on adjacent creeping bentgrass for up to 30 days. Gibberellic acid at 0.12 kg ai/ha and foliar iron at 1.3 kg ai/ha, applied to creeping bentgrass when tracks first appeared, did not enhance recovery of injured creeping bentgrass. Persistence and stability of [2-pyridine 14C] rimsulfuron on turf foliage was also assessed. Rimsulfuron was absorbed by annual bluegrass and perennial ryegrass equivalently and persisted equally on turf foliage. Water extractable rimsulfuron decreased from 60% at 10 minutes after treatment to 40% at 96 hours after treatment. A substantial amount of stable rimsulfuron persists on turf foliage for up to four days. Results from both studies suggest that when applying rimsulfuron near susceptible bentgrass the lowest effective rate should be used, and irrigation should follow two hours after treatment to prevent nontarget injury. / Master of Science
628

Función del gen 3-cetoacil-CoA tiolasa 2 (KAT2) en defensa y desarrollo. Participación de los peroxisomas en las respuestas a herida en Arabidopsis thaliana

Castillo López del Toro, Mª Cruz 15 December 2008 (has links)
La ?-oxidación es un proceso metabólico esencial en las células eucarióticas. Tradicionalmente, esta ruta catabólica ha sido considerada en plantas como la vía principal de degradación de ácidos grasos en las células. Sin embargo, en los últimos años, la ?-oxidación de plantas está siendo objeto de un gran interés científico por su implicación en funciones relacionadas con el desarrollo y la defensa. En este contexto, aunque en estudios bioquímicos previos se había propuesto la participación de reacciones de -oxidación en la biosíntesis de ácido salicílico (SA) y ácido jasmónico (JA), moléculas señalizadoras clave en las respuestas de defensa de plantas frente a patógenos y herida, no se había descrito la implicación de ningún enzima de ?-oxidación hasta la realización de este trabajo. De todos los pasos enzimáticos implicados en esta ruta, la familia de las 3-cetoacil-CoA tiolasas (KAT) son las enzimas y genes menos estudiados. Este trabajo se ha centrado en la caracterización molecular y funcional de los distintos genes que codifican proteínas KAT de Arabidopsis, principalmente del gen KAT2 que codifica la proteína con la función KAT mayoritaria en ?-oxidación en Arabidopsis. Para determinar las posibles funciones del gen KAT2 en procesos relacionados con el desarrollo y con la defensa de las plantas, se generaron plantas transgénicas con pérdida o ganancia de función del gen y otras donde la secuencia promotora de KAT2 se fusionó a genes delatores, las cuales permitieron caracterizar en mayor profundidad el patrón de expresión de este gen en Arabidopsis. Los análisis de expresión realizados demostraron que la herida activa transcripcionalmente genes de -oxidación con un patrón de inducción específico. Concretamente, el gen KAT2 aumentó su expresión a través de una vía de señalización independiente de la señalización mediada por JA y posiblemente dependiente de ácido abcísico. Además, plantas transgénicas con una expresión reducida del gen KAT2 mostrar / Castillo López Del Toro, MC. (2008). Función del gen 3-cetoacil-CoA tiolasa 2 (KAT2) en defensa y desarrollo. Participación de los peroxisomas en las respuestas a herida en Arabidopsis thaliana [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3783
629

Evaluation of Topsoil Substitutes for Restoration of Appalachian Hardwoods on Strip Mined Land

Showalter, Julia M. 05 September 2005 (has links)
Current surface mine reclamation in Appalachia involves returning the land to approximate original contour by grading the surface and planting grasses and early-successional trees. This results in a greatly altered ecosystem compared to the native forest that was there prior to mining. The reclaimed land is usually degraded economically and environmentally because mine soils are usually less productive than the native soils, and because the mined sites do not provide the same level of ecosystem services. This research addressed constraints to the return of the native ecosystem by assessing how mine spoil properties and treatments affect native tree species and soil microorganisms. A 4x2x3 factorial greenhouse experiment was used to examine the growth of one-year-old Fraxinus americana, Quercus rubra, and Liriodendron tulipifera as well as herbaceous plant occurrence and microbial biomass and activity. Three mine spoils, brown, weathered sandstone (BWS), white, unweathered sandstone (WUS), and gray, unweathered shale (GUH) were compared with undisturbed forest topsoil (UFT) to determine their suitability for tree growth. Half of each of the four media was inoculated with a 2.5-cm layer of topsoil. BWS was the optimal spoil material for the growth of F. americana, Q. rubra and microbial populations. Foliar nutrient analysis indicated that L. tulipifera was highly dependent on nutrient levels and was unable to grow well on any of the spoil types due to deficiencies. Inoculation with topsoil increased tree growth on the GUH spoil, and increased microbial activity and presence of herbaceous plants across all growth media. The field study was used to determine what spoil properties most influenced three-year-old Quercus alba growth. This information was used to test a mine quality classification model. Northeast facing sites with sandy spoils high in nutrients, moderate in pH, and high in microbial populations were optimal for tree growth. These variables explained 52% of the variation in tree growth. Tree growth was also highly correlated with tree foliar nutrient levels, further suggesting that tree growth was influenced by spoil nutrients. Microbial biomass and dehydrogenase production were also regressed against soil properties and were dependant on a moderate pH, high nitrogen levels, and low salt content. These variables explained 53% of the variability in microbial biomass and 50% of the variability in enzyme production. These studies suggest that tree growth and soil microbial populations are closely linked, and both are affected by mine spoil properties. During mined land reclamation, mine spoils conducive to tree growth should be selected if return of the native ecosystem is the reclamation goal. / Master of Science
630

The therapeutic value of Aloe Ferox Mill

Mhaladi, Refilwe January 2014 (has links)
Thesis (M. Tech. (Biomedical Technology)) -- Central University of Technology, 2014 / The rising costs of health care, the outbreak of drug resistant organisms, health depleting lifestyles and the risky side effects of currently used drugs are world-wide problems. This has led to the search for novel drugs and drug leads. Traditional healers and other individuals across the globe possess unlimited knowledge on the healing powers of different plants that has been passed on through generations. This knowledge together with scientific investigations can lead to the eradication of most of the diseases either by treatment or prevention. Aloe ferox Mill. is one of the plants that have gained a lot of interest from the pharmaceutical industry. The plant has over 80 documented medicinal uses. These include treatment of impotence and infertility, sexually transmitted infections, arthritis, hypertension, leukaemia, bacterial and fungal infections. It is also known as a blood purifier, widely used as a laxative and anti- inflammatory agent. More research is required to discover more about A. ferox and its benefits to health as well as to investigate its potential for the development of novel drugs. The current study was focused at investigating the anti- cancer, anti- microbial antidiabetic, cytotoxic activities and phytochemical composition of leaf extracts of A. ferox. Three cancer cell lines namely: breast (MCF7), colon (HCT116) and prostate (PC3) cancer cell lines were used to investigate the anticancer activity of the extracts using the Sulforhodamine B (SRB) method. To determine the anti- diabetic activity of the plant extracts the C2C12 and Chang cell in- vitro models of glucose uptake were used. The micro- dilution technique was IV used to evaluate the antibacterial and antifungal activity of the extract. The safety of these extracts against normal human foetal lung fibroblasts (W138), Chang and C2C12 cells was done by through the SRB and the MTT methods. To determine the phytochemical profile of A. ferox the DPPH radical scavenging and the Folin Ciocalteu methods were used to test the antioxidant activity and the total phenolic content of the different extracts respectively. Different methods were used to determine the presence of phytochemicals such as steroids, saponins, alkaloids, carbohydrates and flavonoids. LCMS was also done to detect the elemental composition of the plant extracts. According to the CSIR criteria A. ferox was inactive against the cancer cell lines used. It however exhibited antioxidant activity even at low concentrations, with an EC50 of 0.865 ± 0.783. The methanol extract showed more phenolic content than the dichloromethane and aqueous extracts at a concentration of 5mg/ml. It is believed that the antioxidant activity correlates with the phenolic content and quality of the phenols present in the plant and more assays have to be done to prove this hypothesis. Other phytochemicals found in the extract included saponins, steroids, alkaloids as well as flavonoids. Both the methanol and aqueous extracts of A. ferox caused a significant increase in glucose uptake by C2C12 cells but caused a slightly decreased uptake by the Chang cells. The plant extracts inhibited the growth of Staphylococcus epidermidis, Streptococcus pneumonia, Escherichia coli and Candida albicans at a concentration of 15mg/ml extract. Candida tropicalis and Escherichia faecalis were resistant to A. ferox extracts. Finally the extracts showed no toxic activity against the normal foetal lung fibroblasts, Chang and C2C12 cells validating the safety of this plant for human use. V The results in conjunction with literature findings show A. ferox to be a promising source of drugs and therapeutic agents. Due to the fact that traditional healers already rely on it as treatment for different ailments, it is important that the safety of the plant for use has been validated though other studies and clinical trial still need to be done to fully confirm this. All the information gathered also showed this plant to be of great benefit against major health problems, responsible for millions of deaths each year such as cancer, cardiovascular and inflammatory diseases, and diabetes. There is however still a great need for more investigation to be done on this plant against a vast majority of organisms and diseases so as to fully benefit from it.

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