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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.
181

AN INTEGRATED CULTURAL MANAGEMENT APPROACH FOR BROWN PATCH DISEASE SUPPRESSION IN TALL FESCUE LAWNS

Jada S Powlen (6620417) 24 April 2023 (has links)
<p> Brown patch (caused by various <em>Rhizoctonia </em>and <em>Rhizoctonia-</em>like species) is one of the major summer diseases of tall fescue [<em>Schedonorus arundinaceus</em> (Schreb.) Dumort., nom. cons.]. Fungicides are available to suppress brown patch; however, there is increasing interest to reduce lawn pesticide inputs. Excessive summer nitrogen (N) applications and extended periods of leaf wetness have been suggested to enhance brown patch. Five projects were conducted from 2020 to 2022 to evaluate individual and various combinations of cultural management practices to improve brown patch management strategies through reducing chemical inputs and promoting environmentally sound integrated pest management (IPM) practices. Brown patch host resistance of 15 tall fescue cultivars was evaluated in a controlled environment study and various morphological characteristics were correlated to brown patch severity. A 45% reduction in brown patch was observed with a resistant cultivar, and cultivars with faster growth rates, wider sheath widths and shorter sheath length correlated with reduced brown patch resistance. A field study evaluated five cultivars fertilized with urea-N from April to July, totaling 73.5 or 245.0 kg N ha<sup>-1</sup>. A resistant cultivar had the greatest influence on reducing disease, and N-rate generally did not influence disease severity. Differences in seasonal brown patch was compared in a three-year field study for various natural organic fertilizers. Feather-bone meal and soybean meal-based products decreased disease compared to non-fertilized turf. Chemical suppression of leaf-wetness was studied using different surfactant chemistries applied on a 14 to 21-d application frequency and some chemistries reduced disease. When evaluating the various interactions of cultivar, N rate, and surfactant compared to a granular fungicide, the greatest impact was achieved when planting a resistant cultivar, reducing disease severity by 68%. Additionally, the combination of a resistant cultivar and application of a surfactant had the same seasonal brown patch compared to a susceptible cultivar with fungicide applications during year two of evaluation. In summary, these studies demonstrate significant reductions in brown patch can be achieved when utilizing the aforesaid best management practices which can substantially reduce the need for frequent lawn fungicides.  </p>
182

CARACTERIZACIÓN, TIPIFICACIÓN, SELECCIÓN Y MEJORA GENÉTICA DE VARIEDADES VALENCIANAS DE TOMATE

Figás Moreno, María del Rosario 13 March 2021 (has links)
Tesis por compendio / [ES] El trabajo realizado en la presente tesis pretende contribuir a la puesta en valor de las variedades tradicionales valencianas de tomate. En primer lugar se aborda la caracterización de una colección de 69 entradas de variedades valencianas de tomate de ocho tipos varietales ('De Borseta', 'Cherry', 'Cor¿, 'De Penjar', 'Plana', 'De Pruna', 'Redona' y 'Valenciana') con 64 descriptores convencionales y 38 características del Tomato Analyzer. Se ha puesto de manifiesto que el uso de forma complementaria de la herramienta fenómica del Tomato Analyzer es una nueva estrategia para la caracterización y clasificación de las variedades locales de tomate, así como para la distinción entre tipos varietales relacionados. A pesar del uso generalizado de los descriptores estandarizados de tomate, hay poca información sobre los efectos ambientales sobre los valores de los descriptores y sobre su herencia. La evaluación de 12 entradas de tomate procedentes de siete tipos varietales en tres ambientes diferentes (cultivo convencional aire libre, cultivo ecológico aire libre e invernadero) mediante el uso de 36 descriptores, ha permitido establecer la influencia del sistema de cultivo sobre estos descriptores, encontrándose una amplia gama de variación, y demostrando su utilidad para describir los materiales de tomate, su diversidad y relaciones. Por otra parte, puede ser muy interesante asociar características saludables como un elevado contenido en vitaminas o sustancias antioxidantes beneficiosas para la salud. El análisis de 69 entradas locales valencianas de tomate procedentes de ocho tipos varietales para caracteres como contenido en distintos azúcares, ácidos y antioxidantes puso de manifiesto diferencias significativas entre los tipos varietales ensayados para la mayoría de las características. Los tipos varietales 'Cherry' y 'De Penjar' presentaban mayor materia seca, contenido de sólidos solubles, acidez titulable, índice de sabor, ß-caroteno, ácido ascórbico, fenólicos totales y actividad antioxidante que los otros grupos. Los resultados obtenidos serán útiles para la diferenciación, mejora y selección de variedades locales de tomate con propiedades organolépticas mejoradas. Los estudios de caracterización y tipificación de las variedades tradicionales de tomate son imprescindibles para detectar factores que dificultan su puesta en valor y fomento de la explotación comercial. En este sentido, dentro de esta tesis se han caracterizado 3 poblaciones de tomate 'Valenciana d'El Perelló'. La menor productividad de las selecciones ensayadas en comparación con el control comercial parece ser debida a una concentración de la producción en los 2-3 primeros ramilletes de la planta. En el programa de selección y mejora del tomate 'Valenciana d¿El Perelló' que se ha realizado se dispone de selecciones con una distribución de cuajado mucho más uniforme. Por otra parte, una forma muy interesante de potenciar su cultivo, es obtener variedades resistentes al ToMV, derivándose un conjunto de linajes de este tomate con el gen Tm22 que confiere resistencia al ToMV. En cuanto a la adaptación a las condiciones agroclimáticas locales de las variedades tradicionales, esta característica es fundamental de este tipo de variedades. Así, las plantas de tomate del tipo 'De Penjar', han sido cultivadas tradicionalmente en la región mediterránea. Estos materiales están adaptados a condiciones de campo abierto bajo condiciones de bajo consumo de recursos. Sin embargo, el cultivo bajo invernadero se está expandiendo debido al aumento de su demanda. La evaluación de 12 variedades (siete entradas tradicionales, tres selecciones y dos híbridos) del tipo 'De Penjar' en cultivo al aire libre y en cultivo bajo invernadero ha revelado un alto impacto del ambiente de cultivo sobre las propiedades morfológicas, agronómicas y químicas de variedades de tomate 'De Penjar'y sugiere la necesidad de desarrollar variedade / [CA] El treball realitzat en la present tesi pretén contribuir a la posada en valor de les varietats tradicionals valencianes de tomàquet. En primer lloc s'aborda la caracterització d'una col·lecció de 69 entrades de varietats valencianes de tomàquet de vuit tipus varietals ( 'De Borseta', 'Cherry', 'Cor',' De penjar ',' Plana ',' De Pruna ', 'Redona' i 'Valenciana') amb 64 descriptors convencionals i 38 característiques del Tomato Analyzer. S'ha posat de manifest que l'ús de forma complementària de l'eina fenómica del Tomato Analyzer és una nova estratègia per a la caracterització i classificació de les varietats locals de tomàquet, així com per la distinció entre tipus varietals relacionats. Malgrat l'ús generalitzat dels descriptors estandarditzats de tomàquet, hi ha poca informació sobre els efectes ambientals sobre els valors dels descriptors i sobre la seva herència. L'avaluació de 12 entrades de tomàquet procedents de set tipus varietals en tres ambients diferents (cultiu convencional aire lliure, cultiu ecològic aire lliure i hivernacle) mitjançant l'ús de 36 descriptors, ha permès establir la influència del sistema de cultiu sobre aquests descriptors, trobant una àmplia gamma de variació, i demostrant la seva utilitat per descriure els materials de tomàquet, la seva diversitat i relacions. D'altra banda, pot ser molt interessant associar característiques saludables com un elevat contingut en vitamines o substàncies antioxidants beneficioses per a la salut. L'anàlisi de 69 entrades locals valencianes de tomàquet procedents de vuit tipus varietals per a caràcters com a contingut en diferents sucres, àcids i antioxidants va posar de manifest diferències significatives entre els tipus varietals assajats per a la majoria de les característiques. Els tipus varietals 'Cherry' i 'De penjar' presentaven major matèria seca, contingut de sòlids solubles, acidesa, índex de gust, ß-carotè, àcid ascòrbic, fenòlics totals i activitat antioxidant que els altres grups. Els resultats obtinguts seran útils per a la diferenciació, millora i selecció de varietats locals de tomàquet amb propietats organolèptiques millorades. Els estudis de caracterització i tipificació de les varietats tradicionals de tomàquet són imprescindibles per detectar factors que en dificulten la posada en valor i foment de l'explotació comercial. En aquest sentit, dins d'aquesta tesi s'han caracteritzat març poblacions de tomàquet 'Valenciana d'El Perelló'. La menor productivitat de les seleccions assajades en comparació amb el control comercial sembla ser deguda a una concentració de la producció en els 2-3 primers ramells de la planta. En el programa de selecció i millora del tomàquet 'Valenciana d'El Perelló' que s'ha realitzat es disposa de seleccions amb una distribució de quallat molt més uniforme. D'altra banda, una forma molt interessant de potenciar el seu cultiu, és obtenir varietats resistents al ToMV, derivant un conjunt de llinatges d'aquest tomàquet amb el gen Tm22 que confereix resistència al ToMV. Pel que fa a l'adaptació a les condicions agroclimàtiques locals de les varietats tradicionals, aquesta característica és fonamental d'aquest tipus de varietats. Així, les plantes de tomàquet del tipus 'De penjar', han estat cultivades tradicionalment a la regió mediterrània. Aquests materials estan adaptats a condicions de camp obert sota condicions de baix consum de recursos. No obstant això, el cultiu sota hivernacle s'està expandint causa de l'augment de la seva demanda. L'avaluació de 12 varietats (set entrades tradicionals, 3 seleccions i dues híbrids) del tipus 'De penjar' en cultiu a l'aire lliure i en cultiu sota hivernacle ha revelat un alt impacte de l'ambient de cultiu sobre les propietats morfològiques, agronòmiques i químiques de varietats de tomàquet 'De Penjar'y suggereix la necessitat de desenvolupar varietats específiques adaptades a cultiu baix hivernacle / [EN] The work carried out in this thesis aims to contribute to the valorisation of the traditional Valencian tomato varieties. First, the characterization of a collection of 69 entries of Valencian tomato varieties of eight varietal types ('De Borseta', 'Cherry', 'Cor',' De Penjar ',' Plana ',' De Pruna ', 'Redona' and 'Valenciana') with 64 conventional descriptors and 38 characteristics of the Tomato Analyzer. It has been shown that the complementary use of the Tomato Analyzer's phenomic tool is a new strategy for the characterization and classification of local tomato varieties, as well as for the distinction between related varietal types. Despite the widespread use of standardized tomato descriptors, there is little information about the environmental effects on the values of the descriptors and their inheritance. The evaluation of 12 entries of tomato from seven varietal types in three different environments (conventional open air cultivation, open air ecological cultivation and greenhouse) through the use of 36 descriptors, has allowed to establish the influence of the cultivation system on these descriptors, being a wide range of variation, and demonstrating its usefulness to describe tomato materials, their diversity and relationships. On the other hand, it can be very interesting to associate healthy characteristics such as a high content of vitamins or antioxidant substances beneficial to health. The analysis of 69 Valencian local tomato entries from eight varietal types for characters as content in different sugars, acids and antioxidants revealed significant differences between the varietal types tested for most of the characteristics. The varietal types 'Cherry' and 'De Penjar' had higher dry matter, content of soluble solids, acidity, flavor index, ß-carotene, ascorbic acid, total phenolic and antioxidant activity than the other groups. The results obtained will be useful for the differentiation, improvement and selection of local tomato varieties with improved organoleptic properties. Characterization and typification studies of traditional tomato varieties are essential to detect factors that make it difficult to value and promote commercial exploitation. In this sense, within this thesis 3 populations of tomato 'Valenciana d'El Perelló' have been characterized. The lower productivity of the selections tested compared to the commercial control seems to be due to a concentration of the production in the first 2-3 bunches of the plant. In the program of selection and improvement of the tomato 'Valenciana d'El Perelló' that has been made, selections are available with a much more uniform fruit set distribution. On the other hand, a very interesting way to enhance their crop is to obtain varieties resistant to ToMV, deriving a set of lineages of this tomato with the Tm22 gene that confers resistance to ToMV. Regarding the adaptation to the local agroclimatic conditions of the traditional varieties, this characteristic is fundamental of this type of varieties. Thus, tomato plants of the 'De Penjar' type have traditionally been grown in the Mediterranean region. These materials are adapted to open field conditions under conditions of low resource consumption. However, greenhouse cultivation is expanding due to the increase in demand. The evaluation of 12 varieties (seven traditional entrances, three selections and two hybrids) of the 'De Penjar' type in outdoor cultivation and in greenhouse cultivation has revealed a high impact of the cultivation environment on the morphological, agronomic and chemical properties of varieties of tomato 'De Penjar' and suggests the need to develop specific varieties adapted to greenhouse cultivation. / Figás Moreno, MDR. (2019). CARACTERIZACIÓN, TIPIFICACIÓN, SELECCIÓN Y MEJORA GENÉTICA DE VARIEDADES VALENCIANAS DE TOMATE [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/119449 / Compendio
183

Yield and quality of pomegranate on selected geographical areas in Western Cape Province, South Africa

Mashavhathakha, Khathutshelo Logan 09 1900 (has links)
The pomegranate fruit is one of the high valued crops, but there is insufficient information regarding the fruit properties in South Africa. The aim of the study was to evaluate the physico-chemical properties as well as total phenols, anthocyanin, antioxidant, organic sugars and acids of cultivar Wonderful on three locations of the Western Cape. This study was conducted on mature pomegranate fruits harvested in the 2012 and 2013 seasons. Fruit weight (g), length (mm), and width (mm), peel/aril colour and total arils weights (g) were measured. Fruits were also analysed for total soluble solids (TSS) or °Brix), titratable acidity (TA) and juice pH. Results of the study showed that there were significant differences in all measured factors with the exception of % aril yield between the three locations. Though varied per season, fruits produced at Bonnievalle had better physical and chemical properties than at the other localities. With the exception of Aril hue angle, all measured parameters had significant interaction effect regardless of locality (P<0.05). Total soluble solids content varied from 16.0–17.3 (°Brix), pH values from 2.7–3.0, titratable acid content varied from 1.3–1.7 and maturity index from 9.7–13.4. The anthocyanin, total phenols and antioxidant were in order of 772–1134; 1611–1834 and 12.57–14.84. Organic acids (Citric and Malic) showed differences while Acetic acid was not significant in all areas and organic sugar (fructose, Glucose and Sucrose) all had significant differences. It can also be concluded that changes in colour of peel and arils of pomegranate (cv. Wonderful) was mostly as a result of seasonal variation as well as growing area as evident by the interaction between both main factors. / Agriculture / M.Sc (Agriculture)
184

Yield and quality of pomegranate on selected geographical areas in Western Cape Province, South Africa

Mashavhathakha, Khathutshelo Logan 09 1900 (has links)
The pomegranate fruit is one of the high valued crops, but there is insufficient information regarding the fruit properties in South Africa. The aim of the study was to evaluate the physico-chemical properties as well as total phenols, anthocyanin, antioxidant, organic sugars and acids of cultivar Wonderful on three locations of the Western Cape. This study was conducted on mature pomegranate fruits harvested in the 2012 and 2013 seasons. Fruit weight (g), length (mm), and width (mm), peel/aril colour and total arils weights (g) were measured. Fruits were also analysed for total soluble solids (TSS) or °Brix), titratable acidity (TA) and juice pH. Results of the study showed that there were significant differences in all measured factors with the exception of % aril yield between the three locations. Though varied per season, fruits produced at Bonnievalle had better physical and chemical properties than at the other localities. With the exception of Aril hue angle, all measured parameters had significant interaction effect regardless of locality (P<0.05). Total soluble solids content varied from 16.0–17.3 (°Brix), pH values from 2.7–3.0, titratable acid content varied from 1.3–1.7 and maturity index from 9.7–13.4. The anthocyanin, total phenols and antioxidant were in order of 772–1134; 1611–1834 and 12.57–14.84. Organic acids (Citric and Malic) showed differences while Acetic acid was not significant in all areas and organic sugar (fructose, Glucose and Sucrose) all had significant differences. It can also be concluded that changes in colour of peel and arils of pomegranate (cv. Wonderful) was mostly as a result of seasonal variation as well as growing area as evident by the interaction between both main factors. / Agriculture / M. Sc (Agriculture)
185

Interaction of maize root associated fungi and the western corn rootworm / Wechselwirkungen zwischen Maiswurzel besiedelnden Pilzen und dem Westlichen Maiswurzelbohrer

Kurtz, Benedikt 15 July 2010 (has links)
No description available.
186

Deroulage du peuplier : effets cultivars et stataions sur la qualite des produits derives

El Haouazali, Hafida 23 September 2009 (has links) (PDF)
L'industrie du déroulage est le débouché majeur de la ressource en peuplier constituée de cultivars toujours plus nombreux. Une évaluation de la qualité des bois de ces cultivars est nécessaire pour connaître leur aptitude tant à des emplois conventionnels (emballages légers, contreplaqués) qu'innovants (panneaux LVL - Laminated Veneer Lumber - pour la construction) afin d'orienter les populiculteurs dans leurs choix sylvicoles. Le présent travail participe à cette démarche et porte sur l'aptitude au déroulage de 10 cultivars de peuplier (5 confirmés et 5 en fort développement) issus de 4 types de stations forestières différentes, sur la qualité des placages et les caractéristiques mécaniques des panneaux contreplaqués et LVL. Trois arbres ayant été prélevés par cultivar et par type de station, l'échantillonnage est donc constitué de 120 arbres. Ainsi 40 billons ont été déroulés en conditions de laboratoire en 1.4 mm et 40 en 3 mm. Les 40 billons restants ont été déroulés en industrie pour estimer les rendements qualitatifs et quantitatifs. La qualité des placages a été évaluée en considérant le tuilage, les qualités de surface (rugosité et peluchage), les variations d'épaisseur, la fissuration. Ces placages ont permis de réaliser 320 panneaux contreplaqués et LVL avec 2 types de colles : une PVAC et une MUF. Chaque panneau a été caractérisé par des essais non destructifs et destructifs en flexion et en cisaillement. Il apparait que la qualité du placage ne dépend que de l'épaisseur du déroulage et de la position radiale dans l'arbre. Les performances mécaniques des panneaux sont essentiellement influencées par l'épaisseur du placage et le type de colle. La variabilité inter-cultivar et inter-station reste à tout niveau très faible : il ne convient donc pas d'adapter les conditions de coupe aux différents cultivars mais une réflexion doit être menée sur l'intérêt qu'il pourrait y avoir à augmenter les révolutions du peuplier pour envisager des emplois en construction bois. Des propositions sont amorcées pour atténuer les effets du bois de tension, génératrice de surfaces pelucheuses.
187

Resposta do arroz de terras altas a diferentes doses de carvão vegetal: desenvolvimento da planta e deficiência hídrica / Resposta do arroz de terras altas a diferentes doses de carvão vegetal: desenvolvimento da planta e deficiência hídrica / Response of upland rice to different doses of charcoal, plant development and water deficit / Response of upland rice to different doses of charcoal, plant development and water deficit

PEREIRA, Rogério Gomes 14 February 2011 (has links)
Made available in DSpace on 2014-07-29T16:24:18Z (GMT). No. of bitstreams: 1 Dissertacao Rogerio Gomes Pereira.pdf: 1311913 bytes, checksum: 594d4803b27bb1b817ac16d754681cbb (MD5) Previous issue date: 2011-02-14 / The average national rice yield was 11,3 million tones, with a harvested area of about 2,7 million hectares (IBGE 2010). Part of this comes from upland production systems in savannas that have high acidity, low fertility, with low phosphorus and potassium levels, low cation exchange capacity and high aluminum saturation. Upland rice in the Brazilian savannas (Cerrados) experiences multiple abiotic stresses and is characterized by high levels of uncertainty caused by rainfall variability. The increasing consumption of plant biomass to generate energy has produced products and by-products with high potential for agricultural use. Among these products is charcoal, that, due to its physical-chemical and molecular properties, have beneficial effects for the physical, chemical and biological soil characteristics. The objective of this work was to investigate the effect of charcoal on soil chemical properties and on the development of upland rice, and on the transpiration rate response of upland rice as an alternative to decrease the effect of drought on its growth and development. Two pot experiments were carried out using a random split-plot experimental design. The main treatments (plots) were water stress (WS) and no-water stress (NWS) and the sub treatments (subplots) were different biochar doses, 0% or control (T1), 6% (T2), 12% (T3) and 24% (T4) in growing medium (sand). The plastic pots were randomized within the sub plots with six replications. The total transpirable soil water (TTSW), the p factor, defined as the average fraction of TTSW that can be depleted from the root zone before reduction in transpiration occurs and the normalized transpiration rate (NTR) were determined. Charcoal significantly increased dry matter accumulation and leaf area of rice plants in both experiments and positively affected the chemical and physical soil properties such as water retention and nitrate availability to the plants. Biochar addition increased TTSW, p factor and reduced NTR. Consequently, biochar addition was able to change the moisture threshold (p factor) of the growing medium, up to a maximum concentration of 12%, hence delaying the point where transpiration declines and affects yield. / A safra nacional de arroz foi de 11,3 milhões de toneladas, com uma área colhida de aproximadamente 2,7 milhões hectares (IBGE 2010). Parte desta produção é cultivada em sistema de sequeiro sob solos de cerrados que é caracterizado por apresentar elevada acidez e baixa fertilidade natural, com baixos teores de fósforo, potássio, capacidade de troca catiônica e elevada saturação por alumínio. O arroz de terras altas cultivado no Brasil Central (Cerrados) experimenta múltiplos estresses abióticos e sua produtividade é caracterizada pela incerteza devido à variabilidade na precipitação. O crescente consumo de biomassa vegetal para a geração de energia tem disponibilizado subprodutos com alto potencial para o uso agrícola. Dentre esses subprodutos, destaca-se o carvão vegetal, que devido as suas características físico-químicas e moleculares, tem-se mostrado benéfico para as propriedades físicas, químicas e biológicas do solo. O objetivo deste estudo foi analisar os efeitos de diferentes doses de carvão vegetal de eucalipto na produção de matéria seca na cultura do arroz de terras altas e nas características físico-químicas e hídricas em substrato areia, e na resposta da taxa de transpiração do arroz de terras altas como uma alternativa para minimizar os efeitos da seca no seu desenvolvimento e crescimento. Dois experimentos em vasos foram realizados por meio do delineamento em parcela sub-dividida. A parcela principal foi constituída pelo tratamento deficiência hídrica (WS) e não deficiência hídrica (NWS) e as sub-parcelas pelas diferentes doses de carvão; 0% (controle, T1), 6% (T2), 12% (T3) e 24% (T4) adicionadas no substrato (areia). Os vasos foram inteiramente casualizados nas sub-parcelas com seis repetições por dose de carvão. A quantidade de água transpirável no solo (TTSW), o fator de depleção (p), definido como a fração de água disponível no solo que pode ser retirada da zona radicular antes de ocorrer a redução da taxa de transpiração, e a taxa de transpiração normalizada (NTR) foram determinadas. A adição de carvão ao substrato proporcionou um aumento significativo na produção de matéria seca e área foliar das plantas de arroz em ambos os experimentos. Nos tratamentos T2, T3 e T4, a adição de carvão vegetal alterou significativamente as características químicas e físico-hídricas do solo, aumentando a retenção de água e a disponibilidade de nitrato para as plantas. A adição de carvão aumentou a TTSW, o fator p e reduziu a NTR. Conseqüentemente, o carvão foi responsável por modificar o fator p, até uma concentração máxima de 12% e retardar o ponto no qual o declínio da transpiração afeta o rendimento.

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