Orientador: Edson Luiz Furtado / Banca: Christiane Ceriani Aparecido / Banca: Celso Garcia Auer / Banca: Roberto Antonio Rodella / Banca: Marli Teixeira de Almeida Minhoni / Resumo: Muitas espécies de eucalipto são cultivadas no mundo todo e muitos patógenos evoluíram ou se adaptaram á cultura, principalmente fungos, desde a fase de viveiro até os plantios adultos. A mancha de micosferela é uma das principais doenças e o Eucalyptus globulus uma das espécies mais suscetíveis. O presente estudo foi iniciado a partir de isolamentos monospóricos de espécies fúngicas associadas à mancha de micosferela a partir de folhas e ramos de E. globulus provenientes de Bagé-RS, Pedras Altas-RS, Botucatu-SP, Jacareí-SP e Itapeva-SP, que possibilitou a obtenção de 46 isolados, que foram observados quanto à forma de germinação e crescimento micelial. A determinação das espécies deu-se por meio de PCR com primers da região genômica ITS1 e ITS4 e sequenciamento (vide capítulo 1). Como resultado, várias espécies foram encontradas e descritas. Mudas de E. globulus foram inoculadas pelo método da exposição de mudas sadias à folhas com sintomas de Teratosphaeria nubilosa, por ejeção de ascósporos, em casa de vegetação. Estas mudas foram avaliadas e folhas com os sintomas do fungo foram coletadas a partir da terceira semana até a décima terceira semana da inoculação. Para realização de cortes e estudos histológicos, que permitiram observar a formação dos pseudotécios desde o seu início três semanas após a inoculação, as hifas ascógenas dentro do pseudotécio após nove semanas e a formação das ascas e ascósporos após 11 e 13 semanas, respectivamente (vide capítulo 2). Através de estudos anatômicos, verificou-se que as folhas adultas apresentaram menor intensidade dos sintomas, o que pode estar relacionado com a compactação das células do parênquima, enquanto que as folhas jovens apresentam espaços intercelulares no parênquima lacunoso, no parênquima paliçádico e na câmara subestomática... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Many Eucalyptus species are grown worldwide, and many pathogens have evolved and adapted to the culture. The cultivation of eucalyptus is affected by a number of diseases. Many pathogens occur in several eucalypt species, especially fungi, from the nursery to the planting adults. The Mycosphaerella leaf disease is a major disease and Eucalyptus globulus one of the most susceptible species. This study consisted of spore isolates of fungal species associated with Mycosphaerella leaf disease from leaves and stems of E. globulus from Bage-RS, Pedras Altas-RS, Botucatu-SP, Jacareí-SP, Itapeva-SP, which allowed the collection of 46 isolatesm sequenced (see Chapter 1). As a result, several species were found and described. Seedlings of E.globulus were inoculated by exposure to leaves of healthy seedlings with symptoms of Teratosphaeria nubilosa, for ejection of ascospores in the greenhouse. Seedlings were evaluated, and leaves with the symptoms of the fungus were collected from the third week up to thirteenth week of inoculation. To carry out studies and histological sections, which allowed the formation of the pseudothecia from its beginning three weeks after inoculation, the formation of the ascogenous hyphae within pseudothecia after nine weeks, and the formation of asci and ascospores after 11 and 13 weeks, respectively (see Chapter 2). Through anatomical studies, it was found that if the adult leaves had a lower intensity of symptoms, which may be related to compression of the parenchyma cells, while the young leaves have intercellular spaces in the spongy parenchyma, palisade parenchyma and in substomatal chambers facilitating the formation of stroma (see Chapter 3). Essential oils of leaves and young adults, healthy and stain micosferela were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry. The data of chemical composition and the respective percentages... (Complete abstract click electronic access below) / Doutor

Mathematical and computer modelling have been playing an increasingly important role in the Computer Aided Engineering (CAE) process. Simulation offers great advantages in the development and analysis phase of products and offers a faster, better and more cost effective way than using physical prototypes alone. The ever increasing demand for new and improved products in the vehicle industry has decreased the time available for the development of new vehicles, but at the same time the demands on quality, reliability and mass that are set for the vehicle are becoming ever more stringent. These requirements have lead to the investigation of procedures and methodologies such as virtual prototyping that will reduce the development time of new vehicles without inhibiting the quality of the vehicle. In order to perform effective and reliable simulations in the CAE process, accurate simulation models of the vehicle and its associated systems, subsystems and components are required. In the vehicle dynamics context simulation models of the tyres, suspension, springs, damper, etc, are needed. This study will look at creating a validated model of a leaf spring suspension system used on commercial vehicles. The primary goal set for the model is to be able to predict the forces at the points where the suspension system is attached to the vehicle chassis as the model is to be used in full vehicle durability simulations. The component which will receive a considerable amount of attention in this study is the leaf spring. Leaf springs have been used in vehicle suspensions for many years. Even though leaf springs are frequently used in practice they still hold great challenges in creating accurate mathematical models. It is needless to say that an accurate model of a leaf spring is required if accurate full vehicle models are to be created. As all simulation models in this study are required to be validated against experimental measurements a thorough experimental characterisation of the suspension system of interest, as well as two different leaf springs, are performed. In order to measure the forces between the suspension attachment points and the chassis, two six component load cells were developed, calibrated, verified and validated. This study will primarily focus on the modelling of a multi-leaf spring as well as a parabolic leaf spring. The study starts with a literature study into the various existing modelling techniques for leaf springs. A novel leaf spring model, which is based on a macro modelling view point similar to that used for modelling material behaviour, is developed. One of the modelling techniques found in the literature, i.e. neural networks, is also used to model the leaf spring. The use of neural networks is applied and some of the challenges associated with the method are indicated. The accuracy and efficiency of the physics-based elasto-plastic leaf spring model and the non physics-based neural network model are compared. The modified percentage relative error metric is compared to two other quantitative validation metrics that were identified from the literature study. It is concluded that the modified percentage relative error has certain limitations but that it is able to give an accurate and representative account of the agreement/disagreement between two periodic signals around zero. The modified percentage relative error is used to obtain the accuracies of the elasto-plastic leaf spring models and the neural network model. Both models give good results with the neural network being almost 3 times more computationally efficient. The elasto-plastic leaf spring model, for the multi-leaf spring, is further extended to model the behaviour of a parabolic leaf spring. Qualitative validation using experimental data shows that the elasto-plastic leaf spring model is able to accurately predict the vertical behaviour of both the multi-leaf spring as well as the parabolic leaf spring. The elasto-plastic leaf spring model was also combined with a method that is able to capture the effect of changes in the spring stiffness due to changes in the loaded length. Quantitative validation shows that the method proposed for accounting for the change in stiffness due to changes in the loaded length is able to capture this characteristic of the physical leaf spring. Following a systematic modelling approach the elasto-plastic multi-leaf spring model is incorporated into a model of a simplified version of the physical suspension system. The qualitative validation results from this model show that the model is able to accurately predict the forces that are transmitted from the suspension system to the chassis. The models created in this study can be used in future work and, with the addition of more detail the models, can be extended to create a model of the complete suspension system. / Thesis (PhD(Eng))--University of Pretoria, 2012. / Mechanical and Aeronautical Engineering / unrestricted

The relationship between leaf physiognomy and precipitation has been explored worldwide in regions under different climate conditions. Unlike the linear relationship established between the percentage of woody dicot species with entire margins and mean annual temperature, precipitation has been reported to correlate to different leaf physiognomic characters depending on the region where the correlation is studied. To investigate if precipitation can be calculated from leaf physiognomic characters on the basis of regional sample sites, data from 50 mesic to humid forests in China were analyzed in this study. With data from Chinese forests, the leaf-area analysis based on linear regression between natural logarithms of leaf size and mean annual precipitation (MAP) shows no significant correlation. Both single and multiple linear regression analyses fail to confirm the correlation between leaf physiognomy and precipitation, which may result from the similarity of modern spatial distribution of temperature and precipitation in China. Our results show that, due to variations in climatic conditions among sampling regions, leaf physiognomic characters that correlate to precipitation are not consistent worldwide, and applications of models without considering regional constraints could mislead our understanding of palaeoclimate. Therefore, when choosing a leaf physiognomic model for palaeoclimate reconstructions, it is important to determine if the leaf physiognomy of the palaeoflora lies within the leaf physiognomic spectrum of the model used.

The relationship between leaf physiognomy and precipitation has been explored worldwide in regions under different climate conditions. Unlike the linear relationship established between the percentage of woody dicot species with entire margins and mean annual temperature, precipitation has been reported to correlate to different leaf physiognomic characters depending on the region where the correlation is studied. To investigate if precipitation can be calculated from leaf physiognomic characters on the basis of regional sample sites, data from 50 mesic to humid forests in China were analyzed in this study. With data from Chinese forests, the leaf-area analysis based on linear regression between natural logarithms of leaf size and mean annual precipitation (MAP) shows no significant correlation. Both single and multiple linear regression analyses fail to confirm the correlation between leaf physiognomy and precipitation, which may result from the similarity of modern spatial distribution of temperature and precipitation in China. Our results show that, due to variations in climatic conditions among sampling regions, leaf physiognomic characters that correlate to precipitation are not consistent worldwide, and applications of models without considering regional constraints could mislead our understanding of palaeoclimate. Therefore, when choosing a leaf physiognomic model for palaeoclimate reconstructions, it is important to determine if the leaf physiognomy of the palaeoflora lies within the leaf physiognomic spectrum of the model used.

Demand for tea is increasingly driven by its reported antioxidative properties. To ascertain such efficacy, the antioxidative activity (AA) of freshly brewed commercially available full-leaf white, green, oolong, and black tea was determined using a dynamic method. Various amounts (w/v) of tea were brewed at different temperatures for a constant period of time. The AA was calculated based on the ability of the brew to quench hydroxyl-radicals as quantified by chemiluminescence detection. Black tea had the strongest radical scavenging ability followed by green tea. Their AA was far greater than those of the other two types of tea tested. This efficacy finally eroded on serial dilution to a tea concentration of 0.15625 X 10-4 g/mL. The significant data clearly substantiate the sound premise that tea, particularly black tea, is unique in its dramatic ability to counter the adverse onslaught of radicals that are known contributors to human morbidity and mortality.

Frogeye leaf spot, caused by Cercospora sojina Hara, is a foliar disease affecting soybean (Glycine max (L.) Merr.), often managed by applications of quinone outside inhibitor (QoI) fungicides. In 2013 and 2014, symptomatic leaf samples were collected from Mississippi soybean fields leading to the collection of 634 mono-conidial C. sojina isolates. In vitro bioassays were performed to evaluate the sensitivity of 14 isolates plus a baseline. Resistant and sensitive isolates were characterized by determining the effective fungicide concentrations at which 50% of conidial germination was inhibited (EC50). Additionally, the molecular mechanism of resistance was determined for all 634 isolates. Greater than 93% of C. sojina isolates collected in Mississippi carried the G143A amino acid substitution indicating a shift to a QoI-resistant population throughout Mississippi soybean fields. Greenhouse studies confirmed that due to this amino acid substitution, symptoms caused by QoI-resistant isolates developed in spite of a QoI fungicide application.

Soybean is an economically important crop. It is a selfertilized species grown on vast contiguous acres. These facts predispose soybean to disease epidemics. Cercospora sojina, causal agent of frogeye leaf spot, has reduced United States soybean productivity 0.3 percent on average per year between 2008 and 2010. Several states have reported the pathogen developing resistance to the strobilurin class of fungicides. To date genetic host resistance has been identified as single dominant genes (Rcs1, Rcs2, and Rcs3). However, the lifespans of Rcs1 and Rcs2 were 10 and 16 years respectively. Currently, the Rcs3 locus has been utilized in all major soybean breeding programs of the US and has been for over 20 years. Seventyive accessions of soybean were found to exhibit resistance to multiple races of C. sojina while not exhibiting the Rcs3 haplotype. Twenty of these plant introductions (PIs) were screened by six races within the new race classification system of C. sojina representing all domestic variability of the pathogen. Two agronomically favorable PIs, PI398993 and PI399068, were found in this research to exhibit broad resistance to sources documented to contain most domestic variability of the pathogen. Two segregating populations were developed by crossing PI398993 x ‘Blackhawk’ and PI399068 x Blackhawk. Segregation ratios of F2 as well as F2:3 family seedling screens of both populations indicating single dominant gene action in both resistance sources. Single marker analysis indicated markers associated with the phenotype were indeed on chromosome 16 (MLG J), but possibly beyond Rcs3 in both sources. Interval mapping placed the highest probability of the resistance loci near SNP_171 and SNP_368, 72.86 and 72.48 cM respectively, but distal to the Rcs3 locus. Analysis of reaction ratings also indicated significant influence on phenotype was also associated with markers located at or beyond the published Rcs3 locus. The evidence in this research supports the hypothesis that both PIs may contain a resistance loci, potentially different than Davis, but within the same gene cluster. Equally as likely, the resistance could prove allelic to Davis.

The plant cuticle is a continuous extracellular protective layer covering the outermost surfaces of higher plants that are in contact with the surrounding atmosphere. The primary function of the cuticular lipid membrane, which is mainly composed of biopolymer cutin and cuticular waxes, is to protect the plant organs against uncontrolled water loss. The chemical composition and the biophysical properties of cuticular waxes affect the rate of water diffusion across the cuticle. Fruit transpiration plays an important role in the development and the maintenance of fruit quality. The fruit has been suggested to present better dehydration stress tolerance than the leaf. However, the differences in transpiration and the chemical composition of cuticular waxes between fruit and leaf have yet to be comprehensively investigated. The present study aims to investigate the water permeability and cuticular wax composition of fruit and leaf cuticles of a wide range of plant species and to elucidate the different roles of the cuticular wax components in the transpiration barrier. To address these objectives, fruit and leaf samples from 17 species were investigated. The cuticular transpiration of intact fruits and astomatous adaxial leaf surfaces and the minimum leaf conductance obtained by leaf drying curves for intact leaves were gravimetrically determined for a variety of plant species. The chemical composition of cuticular waxes of fruits and leaves was thoroughly analysed by gas chromatography with flame ionization and mass spectrometry. The water permeability of fruits ranged from 3.7 x 10-5 m s-1 (Prunus domestica subsp. syriaca) to 37.4 x 10-5 m s-1 (Coffea arabica), whereas permeability for leaves varied between 1.6 x 10-5 m s-1 (Cornus officinalis) and 4.5 x 10-5 m s-1 (Prunus domestica subsp. syriaca (L.)). The interspecies range of water permeability of fruits was significantly higher than that of leaves. Chemical analyses of the cuticular waxes demonstrated that fatty acids, primary alcohols, n-alkanes, aldehydes and alkyl esters were the predominant very-long-chain aliphatic compound classes of fruit and leaf surfaces. Sterols, such as β-sitosterol and campesterol, and triterpenoids, such as oleanolic acid, ursolic acid, α-amyrin and ß-amyrin, were the major cyclic compound classes in the cuticular wax membrane. The amount and composition of cuticular waxes of both fruits and leaves varied at an intraspecific level. There were no significant correlations between the total cuticular wax load or the individual cuticular wax composition and the water permeability of fruits or leaves independently or together. After combining the fruit and leaf data set, a significant correlation between the average chain length of very-long-chain aliphatic compounds and permeabilities was detected, i.e. the longer the average chain length, the lower the water permeability. Interestingly, n-Nonacosane (C29) was abundantly detected in fruit waxes of Rosaceae species. These fruits exhibited a relatively low transpiration level, which was very close to their leaf cuticular permeability. The present study suggests that the lower cuticular permeability of leaves, in comparison to that of fruits, may be attributed to the longer average chain length of aliphatic compounds. The accumulation of total wax, triterpenoids and aliphatic compounds may not contribute to the transpiration barrier directly. The present results are highly consistent with the previous model assumptions for the cuticular structure and transport barrier. Furthermore, this comparative study on leaf and fruit cuticles provides further insights linking the cuticular wax chemistry to the physiological properties of the plant cuticle. / Die pflanzliche Kutikula ist eine kontinuierliche extrazelluläre Schutzschicht, welche die oberirdischen primären Abschlussgewebe höherer Pflanzen bedeckt, die in Kontakt mit der umgebenden Atmosphäre stehen. Die primäre Funktion der lipophilen Kutikularmembran, die hauptsächlich aus dem Biopolymer Kutin und kutikulären Wachsen aufgebaut ist, besteht darin, die Pflanzenorgane vor unkontrolliertem Wasserverlust zu schützen. Die chemische Zusammensetzung und die biophysikalischen Eigenschaften von kutikulären Wachsen beeinflussen weitgehend die Geschwindigkeit der Wasserdiffusion über die Kutikula. Die Transpiration von Früchten spielt eine wichtige Rolle in der Ausbildung und Beständigkeit von Fruchtqualitätsmerkmalen. Unterschiede in der Transpiration und der chemischen Zusammensetzung der kutikulären Wachse zwischen Frucht und Blatt sollten untersucht werden. Die vorliegende Studie zielt darauf ab, die Wasserpermeabilität und die kutikuläre Wachszusammensetzung von Früchten und Blättern aus einem breiten Spektrum von Pflanzenarten zu untersuchen und die verschiedenen Rollen der kutikulären Wachskomponenten in den Transpirationsbarriereeigenschaften aufzuklären. Um diesen Zielen näherzukommen, wurden Frucht- und Blattproben von 17 Arten untersucht. Die kutikuläre Transpiration von intakten Früchten und astomatären adaxialen Blattoberflächen ausgewählter Arten sowie der minimale Leitwert von deren Blättern, ermittelt durch Austrocknungskurven mit intakten Blättern, wurden gravimetrisch bestimmt. Die chemische Zusammensetzung der kutikulären Wachse von Früchten und Blättern wurde durch Gaschromatographie mit Flammenionisation und Massenspektrometrie nachgewiesen. Die Wasserdurchlässigkeit von Früchten reichte von 3,7 x 10-5 m s-1 (Prunus domestica subsp. syriaca) bis 37,4 x 10-5 m s-1 (Coffea arabica), während die Werte für Blätter zwischen 1,6 x 10-5 m s-1 (Cornus officinalis) und 4,5 x 10-5 m s-1 variierten (Prunus domestica subsp. syriaca). Der interspezifische Vergleich der Wasserdurchlässigkeit von Früchten war deutlich höher als die der Blätter. Chemische Analysen der kutikulären Wachse zeigten, dass Fettsäuren, primäre Alkohole, n-Alkane, Aldehyde und Alkylester die häufigsten sehr langkettigen aliphatischen Verbindungsklassen für Früchte und Blätter waren. Sterole wie β-Sitosterol und Campesterol und Triterpenoide zum Beispiel Oleanolsäure, Ursolsäure, α-Amyrin und ß-Amyrin, waren die wichtigsten zyklischen Verbindungsklassen in den kutikulären Wachsmischungen. Die Menge und Zusammensetzung der kutikulären Wachse, sowohl von Früchten als auch von Blättern, variierte auf intraspezifischer Ebene. Es waren keine signifikanten Korrelationen zwischen der Menge der kutikulären Wachsablagerung oder der kutikulären Wachszusammensetzung und der Wasserdurchlässigkeit von Frucht- und/oder Blattoberflächen zu erkennen. Wurden die Frucht- und Blattdatensätze zusammen untersucht, so war eine signifikante Korrelation zwischen der durchschnittlichen Kettenlänge von sehr langkettigen aliphatischen Verbindungen und der Permeabilität festzustellen, ging eine längere durchschnittliche Kettenlänge mit geringerer Wasserdurchlässigkeit einher. Interessanterweise wurden große Mengen an n-Nonacosan in Fruchtwachsen der untersuchten Rosaceae-Arten nachgewiesen. Diese Früchte zeigten ein relativ niedriges Transpirationsniveau, das sehr nahe an der Permeabilität ihrer Blattkutikeln lag. Die vorliegende Studie liefert weitere Belege dafür, dass der im Allgemeinen niedrigere minimale Leitwert von Blättern auf die – im Vergleich zur Kutikula von Früchten – längere durchschnittliche Kettenlänge der aliphatischen Verbindungen zurückzuführen ist. Die Anhäufung von Gesamtwachs, Triterpenoiden oder aliphatischen Verbindungen trägt nicht direkt zur Transpirationsbarriere bei. Die vorliegenden Ergebnisse decken sich in hohem Maße mit den bisherigen Modellannahmen zur Struktur der Kutikula und der von ihr vermittelten Funktion als Transpirationsbarriere. Darüber hinaus gibt diese Vergleichsstudie über die Kutikula von Früchten und Blättern zahlreiche Einblicke, die dabei helfen können, die kutikuläre Wachschemie mit den physiologischen Eigenschaften der pflanzlichen Kutikula zu verknüpfen.

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Fruit tree leaf nutrient concentrations are commonly used to determine fertilizer rates, but information is limited regarding nutrient requirements, seasonal N uptake and removal rates, and soil N dynamics for pomegranate. Relationships between fertilizer rates, leaf nutrient concentrations, fruit yield and quality were examined in five mature, commercial California ‘Wonderful’ pomegranate orchards. Site 1 was observed for two growing seasons (2018-2019) and sites 2-5 were observed for one season (2018 or 2019). In 2018, 150, 300, or 450 g N/tree was applied at sites 1-3 in a single application at early fruit development or in two equal applications at early and mid-season fruit development. In 2019, fertilizer rates were adjusted based on site-specific leaf nutrient analysis and crop load and applied at mid-season fruit development (158, 185, 225, 286, 392, or 625 g N/tree at site 1; 115, 130, 150, 175, 212, or 270 g N/tree at site 4; and 107, 122, 142, 171, 214, or 286 g N/tree at site 5). A randomized complete block design was used for all experiments. Leaves were collected from all data trees during early, mid-season and late fruit development and analyzed for leaf nutrient concentrations. At harvest, total fruit weight per tree and individual fruit weight and diameter were measured. Canopy volume was measured during the dormant season prior to pruning. Nitrogen partitioning, uptake and removal rates were studied by analyzing plant tissue, soil, and lysimeter water samples in 2019 at site 5. Fruit yield and average diameter varied significantly depending on site and fertilizer treatments. Average fruit yield per tree ranged from 5-90 kg fruit/tree (site 1: 78.5 kg fruit/tree in 2018 and 91.1 kg fruit/tree in 2019, site 2: 55.6 kg fruit/tree, site 3: 29.7 kg fruit/tree, site 4: 5.6 kg fruit/tree, site 5: 9.1 kg fruit/tree). Sufficiency ranges and significant relationships were determined between certain nutrients, including nitrogen and potassium, to fruit yield and diameter. Higher fertilizer treatments were associated with higher residual soil N compared to the low fertilizer treatments within the root zone (2.25-19.33 mg/L NO3-N) and below the root zone (2.25-9.17 mg/L NO3-N) suggesting a higher likeliness of nitrogen leaching with fertilizer applications exceeding the crop’s nitrogen demand. Overall, variability between sites in fertilizer treatment effects, leaf nitrogen concentrations, and yield suggests that setting site-specific yield goals based on estimated N uptake and removal is necessary to develop effective pomegranate fertilizer programs.