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Fowler, Tiffany B. Rushing Ann E. "Early periderm development in the shoots of Ulmus alata michx." Waco, Tex. : Baylor University, 2006. http://hdl.handle.net/2104/4899.
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Fei, Liwen. "Towards automating micropropagation: from cells to shoots to plants in one step." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-dissertations/195.
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A mist reactor was used to study plant growth and development under various environmental conditions towards the production of healthy plantlets ready for soil transplant in one step from inoculation. In addition, a 3D type of cultivation via surface attachment of explants to vertically hanging strips inside the mist reactor was also investigated to maximize productivity with minimal footprint. Using carrot as the model species, pre-embryogenic cell suspensions were successfully spray-inoculated onto hanging poly-L-lysine (PLL)-coated nylon mesh to which they then attached and remained for several weeks while they developed into rooted plantlets. To study single step micropropagation from shoot explants to fully acclimatized plantlets, Artemisia annua was used as the model species. Nodal cuttings of A. annua were inoculated onto PLL-coated mesh strips by briefly immersing the strips in the suspension of nodal cuttings. Investigation of medium, phytohormones, CO2, ventilation level and humidity ensued resulting in selection of a preferred final process that reduced physiological aberrations like hyperhydricity and was time efficient. The nodal cuttings that attached to the strips were first misted with half strength shooting medium for 7 days to develop new shoots. Then the new shoots were misted with the rooting medium supplemented with NAA for 12 days to develop roots. Rooted plantlets were acclimatized in the same rooting medium for 9 days to acquire fully functional stomata prior to planting into soil. Taken together this study suggested that fully developed plantlets ready for planting into soil could be obtained in a single step in a bioreactor from embryogenic cells or from nodal explants.
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Santos, Vanessa Rebouças dos. "Crescimento, propagação, floração e compostos de reserva em Costus arabicus L." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315649.
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Orientador: Lilian Beatriz Penteado ZaidanTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-13T07:49:31Z (GMT). No. of bitstreams: 1 Santos_VanessaReboucasdos_D.pdf: 832172 bytes, checksum: fd8402411397a7ed317acd370f3b06a3 (MD5) Previous issue date: 2009
Resumo: O mercado mundial da floricultura tem incentivado a introdução e produção de novas plantas tropicais, cujas formas inusitadas, exuberantes e coloridas têm alto potencial ornamental. No Brasil, o cultivo para a produção de flores tropicais vem aumentando, graças às condições ambientais favoráveis, à disponibilidade de terras, água e energia, além da mão de obra relativamente barata, que incidem diretamente na qualidade do produto e possibilitam custos competitivos nos mercados externos. Porém, existem limitações para a expansão de produtos novos, dentre elas, a falta de informação quanto às condições de cultivo intensivo de espécies potenciais e a sua conservação em condições tropicais. As espécies do gênero Costus (Costaceae) vêm despertando grande interesse ornamental devido às suas inflorescências que apresentam beleza e exoticidade. O objetivo do presente trabalho foi estudar o crescimento, a propagação, a floração e os carboidratos de reserva em plantas de Costus arabicus L. cultivadas sob condições de casa de vegetação, com vistas a oferecer conhecimento fisiológico e informações técnicas para o cultivo dessa espécie como planta ornamental. Plantas de C. arabicus foram transplantadas para vasos e mantidas sob condições de casa de vegetação. As plantas foram submetidas a tratamentos fotoperiódicos de 8, 12, 16 e 20 h, avaliando-se o crescimento vegetativo (brotações, hastes, altura e número de folhas) e a floração. Para o estudo da propagação vegetativa, os rizomas de C. arabicus foram divididos em suas regiões distal, mediana e proximal e cultivados em diferentes épocas: plantio realizado em julho (inverno), com as plantas matrizes em estádio prévio à floração; plantio realizado em novembro (primavera), com as plantas matrizes em floração; e plantio realizado em março (outono), com as plantas matrizes em estádio vegetativo. A floração foi avaliada pelo aparecimento de botão floral, pela fase de desenvolvimento da inflorescência, número de flores desenvolvidas e tempo decorrido da antese até a senescência da flor. Foram realizadas análises de amido e carboidratos solúveis (açúcares totais e redutores) do rizoma e foram registradas a massa fresca (MF) e a massa seca (MS) da parte aérea e do rizoma e calculada a razão MF/MS. O delineamento experimental utilizado foi o inteiramente casualizado. As médias dos tratamentos foram comparadas segundo Tukey com 5% de probabilidade. Os resultados indicaram que as variáveis de crescimento analisadas foram influenciadas pelo fotoperíodo e favorecidas por dias longos. De modo geral, a capacidade propagativa do rizoma independe da região utilizada, porém a região proximal favoreceu a formação de brotos, principalmente no verão. Plantas de C. arabicus têm ciclo de desenvolvimento anual, com uma fase de crescimento vegetativo, latência no crescimento na época do inverno e floração entre novembro e abril. Botões florais foram observados em todos os tratamentos fotoperiódicos e, portanto, a indução floral não foi uma resposta qualitativa a esse fator ambiental. Contudo, a resposta de floração, com base nos diversos aspectos avaliados foi favorecida no fotoperíodo de 16 h e em termos quantitativos, fotoperíodo de 8 h foi desfavorável para a floração. A melhor época de plantio visando à floração foi no mês de julho, pois o processo de floração ocorreu após apenas quatro meses de cultivo das plantas, quando comparadas com as plantas obtidas de rizomas cultivados em novembro e março, que levaram aproximadamente 12 e 8 meses, respectivamente, para florescer. O amido foi considerado o principal carboidrato de reserva do rizoma e foi hidrolisado durante o processo de floração, enquanto os açúcares totais foram utilizados como fonte primária de energia para a brotação dos rizomas de plantas de C. arabicus. Os resultados obtidos do crescimento, propagação vegetativa e floração permitem que as plantas de C. arabicus possam ser aproveitadas como plantas ornamentais, visto que suas características morfológicas, como a filotaxia em espiral, a inflorescência esverdeada, as flores brancas com labelo róseo, são aspectos interessantes para o mercado da floricultura.
Abstract: The world market for floriculture is encouraging the introduction and production of new tropical plants, with their unusual forms, exuberant and colorful, with high ornamental potential. In Brazil, the cultivation for production of tropical flowers are increasing due to, favourable environmental factors, availability of land, water, energy and relatively cheap labour which reflects directly on the quality of the products and offers competitive costs in foreign markets. But there are limitations to the expansion of new products, including the misinformation about the conditions of intensive cultivation of new plant species and their potential conservation in tropical conditions. The species of the genus Costus (Costaceae) are attracting great interest because of their ornamental flowers with high beauty and exoticity. The objective of this work was to study propagation, growth, flowering and the reserve compounds in plants of Costus arabicus L. growing under glasshouse conditions, aiming to offer technical information and physiological knowledge for the cultivation of this species as an ornamental plant. Plants of C. arabicus were transplanted to pots and kept under the conditions of a greenhouse. The plants were subjected to photoperiodic treatments of 8, 12, 16 and 20 h. Vegetative growth (shoots, stems, height and number of leaves) and flowering were evaluated. For vegetative propagation, rhizomes of C. arabicus were divided in their distal, middle and proximal regions and were grown in different seasons: planting held in July (winter), when the plants were in a stage prior to flowering; planting held in November (spring), when the plants were flowering and planting held in March (autumn), when the plant were in vegetative stage. Flowering was assessed by the appearance of floral buds, the developmental stage of the inflorescence, the number of flowers developed and elapsed time from anthesis to senescence of the flower. Analysis of soluble starch and carbohydrates (total and reducing carbohydrates) of rhizome were performed. Fresh mass (FM) and dry matter (DM) of the shoot and the rhizome were recorded to calculate the ratio FM/DM. The experimental design was a completely randomized. The averages were compared according to Tukey at 5% probability. The results indicated that the growth of variables analyzed were influenced by photoperiod and favored by long days. In general, the ability of the rhizome to propagate not depends on the region used, but the proximal region favored vegetative growth development, formation of shoots, the development of rods, plant height and number of leaves, mainly on summer. Plants of C. arabicus have annual cycle of development, with a phase of vegetative growth, followed by latency of winter season and flowering between November and April. Floral buds were observed in all photoperiodic treatments, and therefore floral induction was not a qualitative response to this environmental factor. However, the response of flowering, based on the various aspects assessed was favored in the photoperiod of 16 h in quantitative terms, photoperiod of 8 h was unfavorable for flowering. The best season for flowering was when planting is in July, because the process of flowering occurred after only four months of cultivation of the plants, when compared with the plants obtained from rhizomes, cultivated in November and March, which brought about 12 and 8 months, respectively, to flower. Starch was considered the main carbohydrate reserve of rhizome and noted that it was hydrolyzed during the process of flowering, while the total sugar were used as a primary energy source for the sprouting of the rhizomes. The results of growth, vegetative propagation and flowering allow the plants of C. arabicus can be used as ornamental plants since its morphological characteristics, such as spiral phytolaxy, the green inflorescence, and the white flowers with pink labelo, are interesting aspects to the market for floriculture.
Doutorado
Doutor em Biologia Vegetal
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Peterson, John A. "Needleless shoots and loss of apical dominance in greenhouse-grown loblolly pine (Pinus taeda L.)." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06302009-040512/.
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Truskina, Jekaterina. "The role of auxin in cell differentiation in meristems." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN033/document.
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L'auxine régule la croissance et le développement des plantes grâce aux facteurs de transcription de la famille des "AUXIN RESPONSE FACTOR" (ARF). Chez Arabidopsis thaliana en particulier, ARF5, 6, 7, 8 et 19 activent l'expression de gènes cibles en réponse à l'auxine. Ces cinq ARF activateurs contrôlent de façon plus ou moins redondante des processus divers au cours du développement de la plante, notamment la régulation des croissances au niveau des méristèmes racinaires et aériens ainsi que la formation des racines latérales ou des méristèmes axillaires.Chacun de ces cinq ARF activateurs présente des patrons d'expression uniques dans chacun des tissus racinaires et aériens, en association avec leurs fonctions particulières. Il est probable que cette expression tissu-spécifique trouve son origine dans un contrôle différencié de leur transcription. Dans cette étude, des régulateurs amonts de la transcription de ARF5, 6, 7, 8 et 19 ont été identifiés par une méthode haut-débit de crible simple hybride en levure (Y1H). Une procédure d'expression transitoire en protoplastes a permis de confirmer que l'expression de chaque ARF activateur est contrôlée par des régulateurs spécifiques, dont la majorité se comportent comme des répresseurs de la transcription des ARF in planta. Parmi les régulateurs identifiés, les facteurs de transcription ont été étudiés grâce à des mutants pour préciser les interactions in planta. Ces mutants montrent des phénotypes développementaux typiques de perturbations de l'auxine dans les racines et les tiges : altérations des cinétiques de croissance, de l'émergence des organes latéraux ou de réponses à l'auxine et modification de l'expression des ARF activateurs.Par ailleurs, ce travail aborde également les dialogues entre les voies de signalisation de l'auxine et des cytokinines, et en particulier le rôle de ces interactions dans le développement des racines et des tiges. Une des interactions identifiées dans le crible Y1H est la répression de ARF7 par CRF10, un gène membre de la famille des "Cytokinin Response Factors". Nous avons mis en évidence l'importance de cette interaction pour le maintien de l'architecture du méristème apical racinaire, pour la sénescence des feuille et pour la réponse phototropique à la lumière bleue dans les hypocotylesAuxin regulates plant growth and development through the transcription factors of the AUXIN RESPONSE FACTOR (ARF) gene family. Most notably in Arabidopsis thaliana ARF5, 6, 7, 8 and 19 activate expression of target genes in response to auxin. These five ARF activators control both variable and overlapping processes during plant development including regulation of growth at the root and the shoot apical meristems, lateral root and axillary shoot formation. Each of the five ARF activators shows unique tissue-specific expression patterns in the root and the shoot associated with their distinct functions. This tissue-specific expression is likely derived from the differences in the control of ARF activator transcription. In this study the upstream regulators of ARF5, 6, 7, 8 and 19 transcription were identified. This was achieved by utilizing a high-throughput yeast one-hybrid (Y1H) method. The transient protoplast assay revealed that each ARF activator is controlled by specific transcriptional regulators and that the majority of these regulators are repressors of ARF transcription in planta. Mutants of the regulatory transcription factors were utilized to additionally investigate the interactions in planta. These mutants display auxin-related developmental phenotypes in the root and the shoot including alternations in growth kinetics, emergence of lateral organs, responses to auxin and altered expression of ARF activators. Furthermore, this study additionally focuses on cross-talk between the auxin and cytokinin signaling pathways and its role in root and shoot development. One of the interactions identified in the Y1H screen is a repression of ARF7 by CRF10, a member of the Cytokinin Response Factors gene family. The importance of this interaction in maintaining architecture of the root apical meristem, in leaf senescence and in the phototropic response to blue light in hypocotyls is studied
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Montagu, Kelvin D. "Whole plant response to soil compaction : from field practices to mechanisms /." View thesis View thesis, 1995. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030522.092251/index.html.
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Israelsson, Maria. "Gibberellin homeostasis and biosynthesis in relation to shoot growth in hybrid aspen /." Umeå : Dept. of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s307.pdf.
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Montagu, Kelvin D., of Western Sydney Hawkesbury University, Faculty of Agriculture and Horticulture, and School of Horticulture. "Whole plant response to soil compaction : from field practices to mechanisms." THESIS_FAH_HOR_Montagu_K.xml, 1995. http://handle.uws.edu.au:8081/1959.7/433.
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This thesis examines the growth response and inter-relationships between shoots and roots of plants grown in compact soil. In the field, two topsoil and two subsoil conditions were created with five vegetable crops sequentially grown. Between 6 and 12% of the root system grew in the compact subsoil, which had a soil strength of 3.1 c.f. 1.9 MPa in the loosened subsoil. Both the root length density (Lv) and the specific root length were lower in the compact subsoil (80% and 30%, respectively). This had no effect on shoot growth when water and nutrients were well supplied. Compensatory root growth in the lose soil above the compact subsoil occurred in broccoli plants. As a result plants grown in soil with or without a compact subsoil had a similar total root length but with altered root distribution. When the water and nitrogen supplied to the soil was reduced, the lower subsoil Lv in the compact subsoil did not restrict water or N acquisition. This was possibly due to a large increase in the specific uptake per unit length of root, by the fewer roots in the compact subsoil. Compared to the subsoil treatments, only small changes in topsoil physical properties occurred when tillage was ceased. From the field trials the proportion and time of root growth into compact soil appeared important in determining the plant response. In a series of split-root experiments (horizontal and vertical arrangements of compact and loose soil) compensatory root growth in the loose soil only occurred when the root system was exposed to horizontally compact soil When compensatory root growth did not occur shoot growth was reduced. This resulted in there being a close relationship between total root length and leaf area. Further test results support a direct effect of mechanical impedance on shoot growth with a rapid (within 10 minutes) and large (50%) reduction in leaf elongation occurring when roots were mechanically impeded. In the field only plants whose roots were totally exposed to compact soil had reduced shoot growth with very compact subsoil having no effect.Doctor of Philosophy (PhD)
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Meintjes, Jacobus Johannes. "An advanced evaluation of prohexadione-calcium on apple, pear, plum and nectarine trees." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49827.
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Thesis (MSc)--Stellenbosch University, 2004.Full text to be digitised and attached to bibliographic record.
ENGLISH ABSTRACT: The control of excessive vegetative growth is important in deciduous fruit orchards. Currently the plant growth regulator prohexadione-calcium (p-Ca) is used to control apple shoot growth in the Untited States of America and some European countries. The effect of P-Ca on the shoot and fruit growth of apples (Malus domestica B.), pears (Pyrus cummunis L.), plums (Prunus sa/icina L.) and nectarines (Prunus persica L.) was evaluated. Inhibition of shoot growth can effect fruit growth. Therefore I did a literature review on the fruit growth of pome- and stone fruit. Split pit, a physiological disorder associated with an increased fruit growth rate in stone fruit, was also investigated. During the course of the 2001 / 2002 season two trials were conducted in the Villiersdorp area of the Western Cape on 'Golden Delicious' and 'Granny Smith' apple trees. Single and multiple applications of P-Ca at different rates, with and without the surfactant Dash®, were applied. One of these trials was continued during the 2002 / 2003 season. In the 2001 / 2002 season, P-Ca reduced shoot growth in both trials on 'Golden Delicious'. The shoot growth of 'Granny Smith' was reduced in both trials where PCa was applied three or four times. There was an improvement in the fruit size of 'Golden Delicious' in both trials, but there was no improvement in the fruit size of 'Granny Smith'. In the 2002 / 2003 season, the single P-Ca application did not reduce shoot growth. Unfortunately 'Golden Delicious' was harvested before any data were obtained. Once again P-Ca had no effect on the fruit size of 'Granny Smith'. Dash® did not improve the effect ofP-Ca. In the 2002 / 2003 season we replicated one trial on five different pear cultivars in the Wolsely area of the Western Cape. Single and multiple applications of P-Ca at different rates were compared to a girdling treatment (2 weeks after full bloom). 'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' and 'Packham's Triumph' pear trees were used and Dash®was added to all 0f the treatments. P-Ca reduced shoot growth in all of the pear cultivars. Girdling reduced shoot growth only in 'Forelle'. P-Ca increased fruit set of 'Early Bon Chretien', 'Rosemarie' and 'Forelle', however, this was associated with a reduced fruit size of 'Early Bon Chretien' and 'Rosemarie'. Girdling did not increase fruit set, but increased fruit size of 'Flamingo' and 'Early Bon Chretien'. P-Ca reduced return bloom of 'Packham's Triumph' and 'Forelle', whereas girdling increased return bloom in all the cultivars except 'Packham's Triumph'. In the 2002 / 2003 season, trials were also conducted on 'Pioneer' and 'Songold' plums and 'May Glo' nectarine in the Wemmershoek and Stellenbosch area of the Western Cape. Single applications at different rates of P-Ca were applied. Dash® was added to all of the treatments. The higher rates of P-Ca reduced the shoot growth of 'Pioneer'. P-Ca only reduced shoot growth of 'Songold' initially and but did not reduce shoot growth of 'May Glo'. P-Ca had no influence on fruit size of 'Pioneer', 'Songold' or 'May Glo'. P-Ca did not aggravate the occurrence of split pit. In conclusion, P-Ca reduced shoot growth in apples and pears when applied at the appropriate rates. Although P-Ca reduced shoot growth of 'Pioneer' plum, more research needs to be done on stone fruit to optimise timing and rate of P-Ca applications.
AFRIKAANSE OPSOMMING: Die beheer van oormatige lootgroei is van kardinale belang in vrugtebome. Tans word die plantgroeireguleerder proheksadioon-kalsium (P-Ca) gebruik om die lootgroei van appels te beheer in die Verenigde State van Amerika en sekere lande in Europa. Die effek van P-Ca op lootgroei en vruggrootte is in proewe op appels (Malus domestica B.), pere (Pyrus cummunis L.), pruime (Prunus salicina L.) en nekatriens (Prunus persica L.) geëvalueer. Aangesien lootgroei inhibisie moontlik vruggroei kan vesnel, is 'n literatuurstudie oor die vruggroei van kern-en steenvrugte gedoen. Die ontwikkelling van gesplete pit by steenvrugte ('n fisiologiese defek geassosieer met versnelde vruggroei) is ook ondersoek. Gedurende die 2001 / 2002 seisoen is P-Ca in twee afsonderlike proewe in die Villiersdorp area van die Wes Kaap geëvalueer. Enkel en veelvuldige toedienings van verskeie konsentrasies P-Ca, met en sonder die benatter Dash", is op 'Golden Delicious' en 'Granny Smith' bome toegedien. Een proef is herhaal gedurende die 2002 / 2003 seisoen. In die 2001 /2002 seisoen het die P-Ca behandelings in beide proewe die lootgroei van 'Golden Delicious' verminder. Die lootgroei van 'Granny Smith' is in beide proewe verminder waar P-Ca 3 of 4 keer toegedien is. Die vruggrootte van 'Golden Delicious', maar nie 'Granny Smith' nie, is in beide proewe deur die P-Ca verbeter. In die 2002 / 2003 seisoen kon die enkeltoedienings van P-Ca nie die lootgroei verminder van 'Golden Delicious' of 'Granny Smith' nie. 'Golden Delicious' is geoes voor enige inligting oor die vruggrootte ingesamel kon word. Weereens het PCa geen invloed op die vruggrootte van 'Granny Smith' gehad nie. Dash® het nie die effek van P-Ca verbeter nie.In die 2002 / 2003 seisoen is proewe met P-Ca gedoen op 5 verskillende peer kultivars in die Wolsely area van die Wes Kaap. P-Ca is teen verskillende konsentrasies, met enkel en veelvuldige bespuitings toegedien en vergelyk met 'n ringelerings behandeling (2 weke na volblom). 'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' en 'Packham's Triumph' bome is gebruik en die benatter Dash® is by al die behandelings gevoeg P-Ca toedienings het lootgroei verminder in 'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' en 'Packham's Triumph'. Ringelering kon slegs die lootgroei van 'Forelle' verminder. P-Ca het die vrugset van 'Early Bon Chretien', 'Rosemarie'en 'Forelle' verhoog. Die toename in vrugset het gelei tot 'n afname in die vruggrootte van 'Early Bon Chretien' en 'Rosemarie'. Ringelering het die vruggrootte van 'Flamingo' en 'Early Bon Chretien' verbeter. P-Ca het 'n afname in die hoeveelheid reproduktiewe knoppe in die volgende seisoen, van 'Packham's Triumph' en 'Forelle' veroorsaak. Ringelering het 'n toename in die hoeveelheid vegetatiewe knoppe in die volgende seisoen gehad vir al die kultivars, behalwe 'Packham's Triumph'. Geduerende dieselfde seisoen is daar ook proewe gedoen op 'Pioneer' en 'Songold' pruime en 'May Glo' nektarienbome in onderskeidelik die Wemmershoek en Stellenbosch areas van die Wes Kaap. Bome is met enkel toedienings van verskillende konsentrasies P-Ca behandel en die benatter Dash® is by al die behandelings bygevoeg. Die hoër dosisse P-Ca het die lootgroei van 'Pioneer' verminder. P-Ca kon slegs die aanvanklike lootgroei op 'Songold' verminder en kon nie lootgroei van 'May Glo' beperk nie. P-Ca het geen invloed op die vruggrootte van 'Pioneer', 'Songold' of 'May Glo' gehad nie. P-Ca het nie die voorkoms van gesplete-pit vererger nie. Om saam te vat kan gesê word dat P-Ca lootgroei op appels en pere goed beperk teen die regte konsentrasies. Alhoewel P-Ca lootgroei suksesvol beheer het op 'Pioneer', moet daar meer werk gedoen word op steenvrugte.
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Kosiba, Andrea. "Effects of irradiation and temperature on shoot growth and development in Blue holly (Ilex x meserveae) /." SLU Alnarp : Department of Crop Science, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/200541.pdf.
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Cartier, Julie. "Short-term advantages of outcrossing in the autogamous wildflower Corydalis sempervirens." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72031.
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Self-fertilization requires less energetic expenditures than cross-fertilization and benefits from a 50% advantage in its rate of gene transmission. Yet, no plant species is known that reproduces exclusively via self-fertilization, as all appear to maintain a certain outcrossing rate. I test the hypothesis that, under specific circumstances, cross-fertilization provides short-term advantages over self-fertilization in Corydalis sempervirens, a self-compatible winter annual.Some fitness components of selfed and crossed progeny were compared under different experimental conditions. Crossed progeny derived short-term advantages from both their higher mean individual heterozygosity and their greater genotypic diversity. Overall, they had higher mean fitnesses than selfed individuals (heterosis), especially in favorable environments. Crossed progeny also displayed greater constancy of yield under increasing densities. In all test-environments, the few individuals with highest fitness resulted from outcrossing. However, as a group, crossed offspring did not have higher fitness values than selfed offspring and not all crosses generated progeny with equally high fitness. The fittest individuals were produced in crosses between parents which shared an intermediate number of common ancestors.
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Hoto, N. A. (Nceba Antony). "Bugweed, a short fibre source of high potential." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53315.
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Thesis (MFor ) -- University of Stellenbosch, 2003.ENGLISH ABSTRACT: The bulk of paper grades destined for the printing industry are produced on modern paper machines which continuously become wider and faster. In order to improve printability, print quality and dimensional stability, such papers contain a large percentage of mineral pigments either in the form of internal loading or external coatings. Although mineral pigments exercise a substantial beneficial effect on paper surface quality, unfortunately these minerals do not contribute towards sheet strength and machine runnability. Today's papermakers are faced with the dilemma of producing highly filled and coated printing papers with low grammages on faster running paper machines, but often lacking the required quality of fibre resources to secure a smooth runnability of such at high speeds. Standard fibre furnishes will have to be upgraded with special types of reinforcing fibres in order to meet the demands of sheet strength and machine runnability. The investigation had succeeded to identify a new suitable fibre resource, which would satisfy the demand of a reinforcing type natural material.
AFRIKAANSE OPSOMMING: Die oorgrootte meerderheid tipes papier wat vir die drukkersbedryf bestem is, word op moderne papiermasjiene vervaardig wat steeds breër en vinniger word. Om die drukbaarheid, drukkwaliteit en dimensionele stabiliteit te verbeter, bevat sulke papiere groot hoeveelhede minerale pigmente wat in die vorm van interne ladings of as eksterne bestrykings teenwoordig is. Alhoewel minerale pigmente -n merkbare voordelige effek op die papier oppervlakte-kwaliteit uittoefen, dra sulke pigmente ongelukkig nie by tot die sterkte en loopvermoë van die papier nie. Die hedendaagse papiervervaardiger word konfronteer met die dilemma om swaar gevuldeen bestrykte drukpapiere met lae oppervlaktegewig op vinniger lopende papiermasjiene te vervaardig. Dit gebeur dikwels sonder die beskikbaarheid van die nodige hoëkwaliteit veselbronne om te verseker dat die loopvermoë van die papier teen hoë spoed nie benadeel word nie. Standaard veselsamestellings salopgegradeer moet word met spesiale tipe versterkingsvesels om aan die uitdaging van hoë velsterkte en masjien-Ioopvermoë te voldoen. Hierdie ondersoek het daarin geslaag om 'n nuwe geskikte veselbron te dentifiseer en wat aandie behoeftes van 'n versterkingsvesel sal voldoen.
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Kanakis, Andreas G. "In vitro plant regeneration studies with Capsicum annuum." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380371.
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Telewski, Frank W. "Determining the Germination Date of Woody Plants: A Proposed Method for Locating the Root/Shoot Interface." Tree-Ring Society, 1993. http://hdl.handle.net/10150/262369.
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A method for determining the germination dates of trees is based on wood anatomical characteristics and dendrochronology. This procedure requires destructive sampling of the tree for an extensive analysis of the zone between the roots and the trunk of the tree (root/shoot interface). The method is applicable to forest ecology and woody plant life history studies.
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McPhee, Christopher Scott. "Investigation of the interaction between root competition and shoot competition in plants." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ36059.pdf.
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Amaya, Iraida. "Centoradialis and the control of plant architecture." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302230.
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Herrington, Edward John. "Light quality effects on in vitro shoot proliferation of Spiraea nipponica." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28809.
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The work on Spiraea in vitro shoot cultures was done to determine the feasibility of using light quality to modify endogenous phytohormone balances to decrease apical dominance. Such an effect would enable a reduction in the high levels of exogenous cytokinin benzyladenine (BA) applied in culture and thus reduce potential side-effects.
The Spiraea in vitro light quality response was characterized by examining the effects of different light wavelengths on growth. A mixture of red/FR induced rates of shoot proliferation with 0.25 mg/1 BA that were as high as rates obtained under white light with 0.5 mg/1 BA. Shoot quality, as determined by the proportion of shoots 1 cm or longer (useful shoots), was highest under red/FR light. The lowest shoot proliferation rate was observed under blue light. When light wavelengths intermediate between blue and red light (green, yellow, and orange) were applied to explants only minor growth modifications occurred. Green light did not inhibit shoot initiation but inhibited shoot elongation at the 0.5 mg/1 BA level.
The efficacy of the light source-filter combinations in the first experiment was studied in two further experiments. With the three light sources (tungsten filament, fluorescent, and metal halide) together with a blue filter, results supported the putative blue light inhibitory effect suggested in the first light quality experiment. Under the red filter, the tungsten filament source induced the highest shoot number means at both
BA levels used (0.25 and 0.5 mg/1).
Two factors may have contributed to the red/FR effect observed in the first experiment; the time under an incubation light regime before transfer to the treatment regime, and the photon fluence rate of each regime. In the subsequent study to examine these factors, shoot initiation was optimized at the lower BA levels of 0.25 and 0.4 mg/1 when cultures under low fluence red/FR were transferred after four weeks to white light of a higher fluence for one more week.
Glyphosate, a known promoter of IAA oxidation, was used to investigate the presumed effect of lowered IAA-cytokinin interactions. Two types of responses to glyphosate occurred, each one dependent on the glyphosate concentration. At the lower glyphosate level (0.087 mg/1), cultures under both light regimes with 0.25 mg/1 of BA, showed a strong inhibition of shoot initiation. This inhibitory effect was overcome in cultures with 0.5 mg/1 of BA and an overall stimulatory response occurred as shoot initiation rates were as much as four-fold higher than in the previous experiments. For both BA levels, changes in shoot number were greater under white light than under red/FR. At the higher glyphosate level (0.2 67 mg/1), the shoot initiation rates were greater than glyphosate-free controls for both BA levels under white light although under red/FR the rates were virtually unchanged from controls. The glyphosate effect investigated for Spiraea cultures appears to be influenced by the levels of the cytokinin BA resulting in pleiotropic effects which depend on the specific concentrations of each component.Land and Food Systems, Faculty of
Graduate
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Ebida, Aly Ibrahim Aly. "Evaluation of phenotypic stability and salinity tolerance in tissue culture : propagated plants of strawberry (Fragaria x ananassa Duch.) cultivar 'Tioga'." Thesis, Imperial College London, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273270.
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Summers, Jacqueline Elizabeth. "Regulation of shoot extension in overwintering tubers of Potamogeton pectinatus L in aerobic and anaerobic conditions." Thesis, University of Bristol, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337261.
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Boul, H. Lawrence. "A study of shoot regeneration in leaf disc cultures of two solanaceous plants." Thesis, University of Canterbury. Botany, 1992. http://hdl.handle.net/10092/5678.
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The behaviour of Solanum laciniatum and "Mitchell" Petunia leaf discs in culture was examined. In both systems shoots were formed in response to an appropriate auxin/cytokinin balance via a caulogenic pathway involving the epidermal tissues with no intermediate callus. Petunia explants could also be induced to form roots, which were found to have an endogenous origin quite different to that observed for shoots. The shoot inducing hormone balance was found to be required for only a short window in the shoot formation timecourse. The hormone balance required to make explants competent for shoot initiation, was less specific than that required for them to become determined for shoot development. Development itself would occur on a medium devoid of growth regulators.
The effect of culturing explants on ungelled medium was also examined. The number of shoots initiated was dramatically increased over those on agar gelled media for both species. Liquid cultured Petunia explants showed an increase in both the number of shoots developing per explant and the rate of development.
The effects of a number of reagents on shoot formation from Solanum laciniatum and Petunia explants was examined as was the effect of the nitrogen source on Petunia explants. The response of explants of both species to 2,3,5 triiodobenzoic acid (TIBA) , ribose, sorbitol and acetylsalicylic acid (ASA) was similar although the sensitivities varied. TIBA was found to promote shoot formation at low concentrations, but inhibit it at higher levels. Ribose, sorbitol and ASA inhibited shoot formation from explants of both species, and partial substitution of Murashige and Skoog nitrogen with NH4Cl inhibited shoot formation from explants of Petunia.
Changes in gene expression accompanying shoot, root and callus production in Petunia explants were monitored by two dimensional polyacrylamide gel electrophoresis of both total extractable protein, and labelled newly synthesised proteins (for shoot and callus forming cultures). In addition the protein profiles of shoot forming cultures inhibited with ASA, TIBA and NH4Cl were also examined. A single silver stainable protein specific to shoot forming cultures, and 4 proteins specific to root formation were discovered. In general, protein changes in the first 4 days of culture greatly exceeded subsequent changes for all three culture systems. The patterns of proteins observed from explants cultured on the three inhibitors were similar. The inhibitors did not prevent the formation of the shoot specific protein, but did result in other changes in protein profile. The most significant of these was the occurrence of a labelled protein which was also found to occur in the nonshoot-forming central portion of uninhibited explants.
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Dzahini-Obiatey, Henry Kwame. "Cytopathological and Molecular Studies of Cacao Swollen Shoot Badnavirus (CSSV) Infected Cocoa Plants." Thesis, University of Reading, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485583.
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The cytopathological and molecular studies of cacao swollen shoot virus (CSSV) infected cocoa plants, which was aimed at identifying structural and functional changes associated with CSSV infections that can be used as resistant markers has yielded interesting results. Nucleic-acid-rich spherical inclusion bodies, modified plastids, invagination of cell walls, apoptotic cells, massive deposition of phenolic substances in infected cells, in situ localisation of CSSV particles in novel cocoa tissues and the apparent aggregation of starch granules in infected tissues were changes that were found to be accompanying CSSV infection by microscopy. Since most of these discoveries were new in CSSV research, they were validated using PCR (conventional and quantitative (qPCR», flow cytomefry (FCM) and laser scanning confocal microscopy (LSCM). The qPCR assay, which was developed from the scratch to measure the CSSV content in infected cocoa plants, has since been used to start building profiles of CSSV resistant cocoa cultivars from Ghana. It was also used to· compare the viral load between the cotyledons and leaves of an infected cocoa plant, whereby the cotyledons were found to have 4-folds more CSSV than the leaves. The qPCR assay has also been used to start studying the movement of CSSV in infected cocoa plants. The FCM was used to confirm apoptotic outcome in CSSV infected plants. This was shown by a reduction in total nuclei DNA between infected and healthy plants at magnitudes which correspond to the microscopic observations. Results from the LSCM were inconclusive. Light microscopic analysis of nucleicacid- rich inclusion bodies, which would have added to building a more robust profile ofthe CSSV resistant cocoa cultivars from Ghana could not be completed due to time constraints. The significance of all these findings in breeding ~or CSSV resistant cocoa, and in CSSV research is discussed.
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Egekwu, Chioma. "Influence of nitrogen and sink competition on shoot growth of poplar." Thesis, University of Maryland, College Park, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10130093.
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Terrestrial and oceanic biomass carbon sinks help reduce anthropogenic CO2 emissions and mitigate the long-term effect of increasing atmospheric CO2. Woody plants have large carbon pools because of their long residence time, however N availability can negatively impact tree responses to elevated CO2. Seasonal cycling of internal N in trees is a component that contributes to fitness especially in N limited environments. It involves resorption from senescing leaves of deciduous trees and storage as vegetative storage proteins (VSP) in perennial organs. Populus is a model organism for tree biology that efficiently recycles N. Bark storage proteins (BSP) are the most abundant VSP that serves as seasonal N reserves. Here I show how poplar growth is influenced by N availability and how growth is influenced by shoot competition for stored N reserves. I also provide data that indicates that auxin mediates BSP catabolism during renewed shoot growth. Understanding the components of N accumulation, remobilization and utilization can provide insights leading to increasing N use efficiency (NUE) of perennial plants.
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Guckenberger, Julie Lynn. "Above-grade improves post-transplant root and shoot growth and physiology of native shrubs." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Fall%20Theses/Guckenberger_Julie_49.pdf.
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Khalil, Aveen. "Assessing the responses of wheat roots and shoots to variations in soil water, temperature and CO2 concentration." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/41101/.
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Wheat (Triticum aestivum L.) is one of the most important cereal crops in the world. In order to meet the food requirements of the current trend in population growth, enhancement in wheat production and yield are urgently needed. Water and temperature stress are major constraints to wheat production and subsequently food security in the context of climate change. Plant growth is affected by both above- and belowground environmental conditions and increasing atmospheric CO2 concentrations have been reported to enhance growth and yield of most agricultural crops. The responses of wheat roots and shoots to variations in soil water, temperature and CO2 concentration were studied in this research. X-ray Computed Tomography (X-ray CT) was used to visualise and quantify the behaviour of roots grown in soil under contrasting conditions for water content, temperature and CO2 concentration. Photosynthesis, stomatal conductance and transpiration were also measured to examine the shoot behaviour under the same environmental conditions. The results showed that total root volume (after 14 days) under the combined effect of elevated CO2 and temperature and mean root diameter for all experiments increased significantly with increasing water stress. However, total root volume decreased significantly under the effect of water stress independently and in combination with elevated CO2 and temperature. Mean root diameter also decreased significantly under repeated soil wetting and drying cycles. Total root volume and mean root diameter at 400 ppm CO2 growth was significantly greater than at 800 ppm CO2 growth at 14 days, while it was significantly lower at 30 days. Photosynthesis, stomatal conductance and transpiration decreased significantly by increasing water stress. Photosynthesis at 800 ppm CO2 was significantly greater than at 400 ppm CO2 while stomatal conductance and transpiration at 400 ppm CO2 were significantly greater. The elevated CO2 enhanced root architecture system and promoted photosynthesis. This research has demonstrated how the interacting variables of water, temperature and CO2 impact on the growth of wheat plants roots and shoots supporting the development of new management strategies for wheat to assist with the food security challenge under a changing environment.
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Rawlins, Isabel Bethan. "Counting planes." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1001816.
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This collection of prose-poems and flash fiction, together with a few short stories, shows how romantic relationships colour our perspectives on the world. The collection has echoes throughout of speakers' voices, theme, imagery and tone. There is a narrative logic too, but working on a subtle level of echo and resonance
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Boother, Gillian Margaret. "Gibberellins and genetic control of shoot growth in barley." Thesis, University of Bristol, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330035.
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Dry, P. R. "Primary bud-axis necrosis of grapevines /." Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09A/09ad798.pdf.
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Koskinen, T. T. "The stability of short-period extrasolar giant planets." Thesis, University College London (University of London), 2008. http://discovery.ucl.ac.uk/1444248/.
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A three-dimensional coupled thermosphere-ionosphere model for extrasolar giant planets (EXOTIM) has been developed. This is the first such model reported in the literature. This thesis contains an extensive description of the model and the methods adopted in modelling the different physical processes expected in the upper atmospheres and ionospheres of extrasolar giant planets. Modelling the upper atmosphere is important because the stability of the atmosphere against thermal evaporation is controlled by the conditions in the thermosphere. The thermosphere is heated by the absorption of EUV and X ray (XUV) radiation emitted by the host star. The radiation also ionises the neutral species in the upper atmosphere, which is expected to be composed mainly of molecular and atomic hydrogen, and atomic helium. Ionisation and subsequent photochemistry leads to the formation of the H+, Hf, H3", and He+ ions (and small quantities of HeH+). H3" emits strongly in the infrared and may act as a significant coolant in gas giant thermospheres. Assuming photochemical equilibrium, the absorption of XUV radiation and ion photochemistry were modelled in a self-consistent fashion. The 3D model can also simulate strong winds affecting the upper atmosphere, and account for both advection and diffusion of the neutral species around the planet. The results indicate that within 1.0 AU from a solar-type host star, the upper atmospheres of Jupiter-type EGPs can be substantially cooler and more stable than implied by studies that ignore the possibility of radiative (Hf) cooling. In this context, a limiting distance, or a stability limit, was identified for such EGPs that depends on the composition of the upper atmosphere and ionosphere, and within which the atmospheres of the planets undergo hydrodynamic escape. Under restricted conditions, this limit is located around 0.15 AU from a Sun-like host star. The model was also used to simulate a newly found transiting planet HD17156b, which orbits its host star on a highly eccentric orbit.
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Lazzarini, Paulo Ricardo Casagrande. "Substâncias húmicas extraídas de turfa associadas com N-ureia: influência no crescimento da cana-de-açúcar e nas transformações do N no solo." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-05052014-104234/.
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As substâncias húmicas (SH) podem alterar o crescimento das plantas bem como estimular a absorção de nutrientes. A ureia é o fertilizante nitrogenado mais utilizado na agricultura, porém, apresenta baixa eficiência de uso. Sabe-se que as substâncias húmicas podem aumentar a eficiência de uso da ureia por meio de efeito bioestimulante no crescimento radicular. Somado a isso, as SH atuam nas bombas de próton das raízes estimulando a absorção de nitrogênio e também alteram a dinâmica de hidrólise e mineralização do N-ureia. O objetivo deste trabalho foi verificar se as SH extraídas de turfa, associadas ou não ao N-ureia, alteram as transformações do N-ureia no solo, assim como o crescimento radicular e da parte aérea no desenvolvimento inicial da cana-planta. Nesse sentido, foram instalados dois experimentos em casa de vegetação, um com a presença de plantas para aferir parâmetros morfológicos e nutricionais e outro, sem plantas, para verificar a dinâmica de hidrólise e mineralização do N-ureia. Os experimentos foram planejados em delineamento experimental inteiramente casualizado com 16 tratamentos e cinco repetições, correspondendo a um esquema fatorial completo com quatro doses de nitrogênio na forma de ureia: 0; 100; 200 e 300 mg dm-3 e quatro doses de SH: 0; 13,8; 27,6; 41,7 mg dm-3 de C, e o experimento sem plantas utilizando o mesmo delineamento porém com 3 repetições e análises feitas em duplicatas. As substâncias húmicas aumentaram a hidrólise da ureia elevando a concentração de NH4+ no solo. O processo de nitrificação da ureia foi reduzido na presença das substâncias húmicas. As aplicações isoladas de N e SHs estimularam o crescimento radicular e da parte aérea da cana-de-açúcar, bem como modificaram as características morfológicas das raízes e parte aérea da cana-planta. A associação dos produtos resultou em decréscimos no crescimento vegetal devido às altas concentrações de amônio causadas pela maior hidrólise da ureia e também atuaram na redução do acúmulo e teor de nitrogênio na planta. Tanto a ureia quanto as SHs se mostraram eficientes no estímulo do crescimento inicial da cana-de-açúcar, no entanto, devido às altas doses de N-ureia utilizadas, o possível efeito sinérgico dos produtos não foi verificado.Humic substances (HS) can alter plant growth and stimulate the absorption of nutrients. Urea is the most widely used nitrogen fertilizer in agriculture, however, has low use efficiency. It is known that humic substances can increase the efficiency of urea through bio-stimulant effect on root growth. Added to this, the SH proton pumps operate in the roots stimulating the uptake of nitrogen and also alter the dynamics of urea\'s hydrolysis and mineralization. The aim of this study was to verify whether the HS extracted from peat, associated or not with N-urea, alter the dynamics of transformation of urea-N in the soil and the growth of roots and shoots in the cane-plant cropcycle. In this direction, two experiments were carried out in a greenhouse, with the presence of plants to assess morphological and nutritional parameters and one without plants, to verify the dynamics of hydrolysis and mineralization of N-urea. The experiments were designed in a completely randomized design with 16 treatments and five replications, corresponding to a full factorial design with four rates of nitrogen as urea: 0, 100, 200 and 300 mg dm-3 and four rates of HS: 0, 13.8, 27.6, 41.7 mg dm-3 C, and experiment without plants using the same design but with three replications and analyzes performed in duplicates. The humic substances increased hydrolysis of urea by raising the concentration of NH4+ in soil. The nitrification of urea was reduced in the presence of humic substances. Individual applications of N and SHs stimulated root and shoot of sugar cane growth and modified the morphological characteristics of roots and shoots in the crop cycle of the cane-plant. The association of the product resulted in decreases in plant growth due to high ammonium concentrations caused by increased hydrolysis of urea and also reduced accumulation and nitrogen content in the plant. Both urea and the SHs were effective in stimulating early growth of sugar cane , however , due to high doses of N-urea used, the synergistic effect of the products has not been verified.
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Wilson, F. D., and H. M. Flint. "Host Plant Resistance." College of Agriculture, University of Arizona (Tucson, AZ), 1986. http://hdl.handle.net/10150/219754.
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The 1985 and 1986 Cotton Reports have the same publication and P-Series numbers.Cotton breeding stocks were evaluated for resistance to pink bollworm. Resistance is being transferred into improved agronomic stocks.
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Chingandu, Nomatter, and Nomatter Chingandu. "Genomic Characterization of the Cacao Swollen Shoot Virus Complex and other Theobroma Cacao-Infecting Badnaviruses." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621859.
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The cacao swollen shoot disease of Theobroma cacao L. (cacao) is caused by Cacao swollen shoot virus (CSSV; genus, Badnavirus, family, Caulimoviridae). The virus is endemic to West Africa, where it poses a serious threat to cocoa production. Despite efforts to control CSSV spread by replacement of infected trees with tolerant cultivars and mealybug vector management, the disease is widespread in West Africa. In Trinidad, leaf mosaic and vein-banding symptoms have been observed in cacao plants in the field since the 1940s, and recently at the International Cocoa Genebank (ICGT), a custodian of cacao germplasm resources. The strains A and B of the suspect Cacao Trinidad virus (CTV) caused the symptoms, and were thought to be related to CSSV, however, viral causality was not demonstrated, until now. To develop molecular detection methods for CSSV in infected plants, polymerase chain reaction (PCR) amplification of eight regions of the CSSV genome was implemented. The PCR results showed variable amplification frequencies of 19 - 42% at each region, for 124 isolates collected in Cote d'Ivoire and Ghana. Pairwise nucleotide (nt) analyses of the eight regions showed 66-99% shared identities, indicating that CSSV isolates exhibit extensive variability with respect to primer design. The results provided preliminary evidence for the existence of a CSSV complex consisting of four divergent species. The full length genome of 14 CSSV isolates from cacao determined using the Illumina HiSeq platform showed 70-99% shared nt identities. The pairwise nt identities placed CSSV sequences into a group of four distinct species, one of which represented a previously undescribed species. Moreover, the full-length genomes grouped phylogenetically with other badnaviruses and revealed two CSSV subclades with three types of genome arrangements; four, five or six open reading frames (ORFs). Predicted functional protein domains were conserved on each ORF. Two distinct, full-length genome sequences were determined using the Illumina HiSeq platform, from DNA isolated from cacao leaves exhibiting distinct symptoms in Trinidad. The sequences were validated by PCR-amplification and sequencing of overlapping viral genome fragments. Pairwise nt analysis indicated that each genome shared 52-62% nt identities with CSSV and other badnaviruses, suggesting that the two are distinct species. Phylogenetic analysis indicated that the two sequences are not strains of the same virus, as supposed, but they represent two previously undescribed species in the genus, Badnavirus, and they have been named Cacao mild mosaic virus (CaMMV) and Cacao yellow-vein-banding virus (CYVBV). Despite sharing the same host and causing similar symptoms in cacao, CSSV, CaMMV, and CYVBV are phylogenetically-distinct species. The discovery of a CSSV species complex and the identification of three new cacao-infecting badnavirus species will support the development of molecular detection tools using the partial and complete genome sequences determined in this study. The ability to develop validated molecular tools for the detection of CSSV and related viruses, CaMMV and CYVBV, in cacao will aid quarantine efforts and safe movement of germplasm from the ICGT in Trinidad to cacao-growing countries, worldwide. Also, molecular diagnostics tools are expected to be useful in efforts underway to develop CSSV-resistant planting material for countries in West Africa, which are currently experiencing continued or new disease outbreaks.
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Javed, Muhammad Tariq. "Mechanisms behind pH changes by plant roots and shoots caused by elevated concentration of toxic elements." Doctoral thesis, Stockholms universitet, Botaniska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-64324.
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Toxic elements are present in polluted water from mines, industrial outlets, storm water etc. Wetland plants take up toxic elements and increase the pH of the medium. In this thesis was investigated how the shoots of submerged plants and roots of emergent plants affected the pH of the surrounding water in the presence of free toxic ions. The aim was to clarify the mechanisms by which these plants change the surrounding water pH in the presence of toxic ions. The influence of Elodea canadensis shoots on the pH of the surrounding water was studied in the presence of cadmium (Cd) at low initial pH (4-5). The involvement of photosynthetic activity in the pH changes was investigated in the presence and absence of Cd. The cytosolic, vacuolar and apoplasmic pH changes as well as cytosolic Cd changes in E. canadensis were monitored. The influence of Eriophorum angustifolium roots on the pH of the surrounding water was investigated in the presence of a combination of Cd, copper, lead, zinc and arsenic at low initial pH (3.5). Eriophorum angustifolium root exudates were analyzed for organic acids. Elodea canadensis shoots increased the pH of the surrounding water, an effect more pronounced with increasing Cd levels and/or increasing plant biomass and increased plant Cd uptake. The pH increase in the presence of free Cd ions was not due to photosynthesis or proton uptake across the plasmalemma or tonoplast. Cadmium was initially sequestered in the apoplasm of E. canadensis and caused its acidosis. Eriophorum angustifolium roots increased the surrounding water pH and this effect was enhanced in the presence of arsenic and metals. This pH increase was found to depend partly on the release of oxalic acid, formic acid and succinic acid by the plants. In conclusion, E. canadensis shoots and E. angustifolium roots were found to increase the low initial pH of the surrounding water. The pH modulation by these species was enhanced by low levels of free toxic ions in the surrounding water.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Submitted. Paper 4: Manuscript.
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Wilson, F. D., and H. M. Flint. "Host Plant Resistance." College of Agriculture, University of Arizona (Tucson, AZ), 1985. http://hdl.handle.net/10150/203923.
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Amakali, Simakeka. "Development of models for short-term load forecasting using artificial neural networks /." [S.l. : s.n.], 2008. http://dk.cput.ac.za/cgi/viewcontent.cgi?article=1031&context=td_cput.
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EL, Itani Samer. "Short-term frequency support utilizing inertial response of variable-speed wind plants." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104853.
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In regions with increasing penetration of variable-speed wind generators, grid operators are concerned about frequency security as system inertia is decreasing. The partial replacement of conventional plants with modern wind plants may cause system frequency regulation to fall below acceptable levels, especially in isolated power systems. This study investigates the contribution of variable-speed wind generators to short-term frequency support. This contribution is obtained by transiently releasing part of the stored kinetic energy in the turbine blades, namely the inertial response. Some inertial response schemes have been researched to be incorporated as auxiliary loops in the controllers of wind generators. First, we compare the performance of these earlier implementations and identify their shortcomings. Then, we quantify the extractable inertial power from a modern wind turbine, given its power characteristic, equivalent inertia, and prevailing wind condition. From this understanding, a new controller, based on the asynchronous release of kinetic energy, is proposed to achieve a superior, more controllable performance. The controller is composed of a 'detection and triggering' scheme that detects the frequency event, a 'power shaping' function that decides the duration and amount of inertial power released, and a 'rotor speed recovery' scheme that brings the turbine back to its optimal speed which corresponds to maximum power tracking. Time-domain simulations were performed to examine the performance of this controller. Based on its impact on system frequency and wind farm operation, the new controller was compared to earlier implementations of wind plant inertial response. The results show that the proposed controller is capable of bringing together the advantages of the different earlier implementations for better grid integration of wind turbine generators. Its effectiveness in reducing the initial frequency fall after a load-generation mismatch promises significant contribution to system inertia. Its controllable, predictable nature is a distinct advantage that enables grid operators to understand, forecast and quantify the impact of incorporating this controller into grid-connected wind generators.Dans les régions à forte pénétration d'éoliennes à vitesse variable, les opérateurs de réseau sont concernés par la sécurité de la fréquence lorsque l'inertie du système décroît. La substitution partielle d'usines conventionnelles par des usines éoliennes modernes pourrait causer le réglage de la fréquence du système à chuter sous des niveaux acceptables, surtout dans le cas de systèmes d'alimentation isolés. Cette étude se penche sur comment les éoliennes à vitesse variable peuvent contribuer au support de la fréquence à court terme. Cette contribution est obtenue grâce au relâchement transitoire d'une partie de l'énergie cinétique contenue dans les aubes de turbine, plus spécifiquement la réponse transitoire. Quelque programmes de réponse inertielle ont été étudiés afin d'être incorporés comme boucle auxiliaire dans les contrôles des génératrices à vent. En premier lieu, on compare la performance d'implémentations préexistantes entre-elles afin d'en identifier les défauts respectifs. En second lieu, on quantifie la puissance inertielle capable d'être extraite d'une génératrice à vent moderne tout en prenant en considération les caractéristiques de puissance, son inertie équivalente ainsi que les conditions de vent dominantes. Avec cette notion, un nouveau régulateur qui est basé sur un relâchement non-synchronisé d'énergie cinétique est proposé afin d'obtenir une performance supérieure et plus contrôlable. Le contrôleur est composé d'un programme de «détection et déclenchement» qui détecte la variation de la fréquence, d'une fonction «formatrice de puissance» qui calcule la durée ainsi que la quantité de puissance cinétique relâchée, et d'un programme de «récupération de vitesse du rotor» qui ramène la turbine à sa vitesse optimale qui correspond au suivi de la vitesse maximale. Des simulations dans le domaine du temps ont été effectuées afin d'examiner la performance du régulateur. À partir de son impact sur la fréquence du système et l'opération de plants éolien, le nouveau contrôleur a été comparé aux implémentations antérieures de réponse inertielle d'usines de vent. Les résultats démontrent que le contrôleur proposé est capable d'unifier les avantages des implémentations précédentes afin d'avoir une meilleure intégration des éoliennes. Sa capacité de réduire la chute de fréquence initiale qui suit un décalage au niveau de la génération de charge promet une contribution significative sur l'inertie du système. En fait, sa nature contrôlable et prévisible lui donne un avantage distinct qui permet aux opérateurs de réseau de pouvoir comprendre, prédire et quantifier l'impact potentiel de l'implémentation de ce régulateur dans des génératrices à vent connectées au réseau.
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Levén, Anna. "Postponed plans : prospective memory and intellectual disability /." Örebro : Linköping : The Swedish Institute for Disability Research, Örebro University ; Department of Behavioural Sciences and Learning, Faculty of Arts and Science, Linköping University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-10382.
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George, Sam. "Botany, sexuality and women's writing 1760-1830 : from modest shoot to forward plant /." Manchester : Manchester university press, 2007. http://catalogue.bnf.fr/ark:/12148/cb41220860f.
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Clouse, Kimberly. "Best Laid Plans and Other Betrayals." ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1523.
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Hood, L. R. "Multiple Plant Growth Regulator Use on Short Staple Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1993. http://hdl.handle.net/10150/209534.
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A field trial was initiated during the 1992 growing season to evaluate the activity of Cytokin and Piz applied alone or in combination to short staple cotton. The Cytokin treatment significantly increased lint yield over the other treatments. There were no statistically significant differences between the non-treated check and any other treatment. The Cytokin treatment increased lint yield an average of 81 pounds over the check plots. Fruit retention remained high throughout the season, indicating that Pix would not normally have been needed.
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Hood, L. R. "Multiple Plant Growth Regulator Use on Short Staple Cotton." College of Agriculture, University of Arizona (Tucson, AZ), 1995. http://hdl.handle.net/10150/210271.
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A field trial was conducted during the 1992 & 1993 growing seasons to evaluate the activity of Cytokin and Pic applied alone or in combination to short staple cotton. The Cytokin treatment significantly increased tint yield over the other treatments in 1992. There were no statistically significant seed cotton differences between the non - treated check and any treatment in 1993. Fruit retention remained high throughout 1992 and very high throughout the 1993 season. Under high fruiting conditions, use of a plant growth regulator would not normally be recommended.
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Van, der Weele Cornelia Maria. "Cell production, expansion and the role of auxin in the response of the root of Arabidopsis thaliana exposed to water deficit /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025657.
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Rheams, Genevieve A. "We Will Plant Birds of Paradise." ScholarWorks@UNO, 2019. https://scholarworks.uno.edu/td/2703.
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Tening, Ndifet Claret Mengwi. "Phytoremediation of Historic Lead Shot Contaminated Soil, Grand Valley Ranch, Northeast Ohio." Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu148534444021035.
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Jokhan, Anjeela Devi. "Root-to-shoot communication in Ricinus communis L. plants subjected to drying a part of the root system." Thesis, University of Bristol, 1997. http://hdl.handle.net/1983/4a9159a4-0a32-457c-bf08-61e6745f8a75.
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This thesis examines the role of root-sourced abscisic acid in the regulation of stomatal closure and leaf expansion in response to drying approximately half of the roots of Ricinus communis L. plants. Drying part of the root system of Ricinus communis promoted stomatal closure and slowed leaf expansion in the absence of any disturbances in shoot water relations, implying the involvement of chemical rather than hydraulic signalling. Initially root-sourced ABA was believed to be responsible for these responses. Delivery rates (concentration x flow rate) of ABA out of the drying roots were calculated which took into account the effect of dilution on solutes in the well-watered and droughted plants due to different transpiration rates in these plants. The delivery term was further modified to account for the differences in sizes of their roots and shoots. ABA delivery out of the roots of plants with drying upper roots increased within the first 12 h and was maintained over the next 3 days. However, significant decline in stomatal apertures and leaf elongation occurred only 2 - 3 days after root drying began. During the early stages of drying upper roots (2-3 d) xylem sap pH, and delivery rate of nitrate and l-aminocyclopropane-l-carboxylic acid were little changed, while hydraulic conductivity of the root system as a whole was reduced approximately 25%, and ABA accumulation (synthesis?) in roots increased. Increased ABA levels in phloem sap was not found, suggesting no enhanced re-cycling of ABA between shoots and roots was taking place in the plants during this time. Antitranspirant activity in xylem sap of droughted plants that was not ABA was sought as a possible cause of stomatal closure. However, convincing evidence of such activity was not found. Examination of ABA output by roots into shoot compared to that entering lamina of the 5th leaf in the canopy showed the attenuation of the signal as transpiration fluid moved up the plant. These obs~f\ations indicate that ABA from roots is unlikely to be a highly active signal eliciting shoot responses to mild drought in Ricinus communis.
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McEwan, Michael. "The antifungal effects of plant essential oils and their production by transformed shoot culture." Thesis, University of Strathclyde, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246327.
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Balasubramanian, Rajagopal. "Harlequin (hlq) : an arabidopsis mutant that ectopically expresses Dc3-GUS and shows defects in cell wall morphogenesis /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?BIOL%202003%20BALASU.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 197-236). Also available in electronic version. Access restricted to campus users.
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Rajagopalan, Jayendar. "Symbolic and connectionist machine learning techniques for short-term electric load forecasting." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08222009-040506/.
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Roman, Mari. "Variabilidade Espacial do Desenvolvimento e da Produtividade do Trigo Triticum aestivum." Universidade Estadual do Oeste do Parana, 2005. http://tede.unioeste.br:8080/tede/handle/tede/378.
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This work had by objective to study and to model the spatial variability of variables relative at the wheat development cultivated in year 2003 in 22,62 ha pertain at Central Co-operative of Agricultural Research (COODETEC). Went used the cultivates Coodetec 101 (3,52 ha) and Coodetec 103 (18,10 ha). The samples went colected in gride of 50 x 50 m, totalized 89 points, the analysis unity a square with 0,25 m2. Went obtained data of emergency seedling, number of s-shoot, height of plants, number of spikes, length spikes, number of grain by spike, weight of thousand seed and production. The spatial dependence went more clear by mean number of s-shoot collected 60 days after to sow and crop height of plants. Variables with relation at the spike and the number of s-shoot 30 days after sow don t had spatial dependence. The others variables went considered with spatial dependence. To the variable spatial independence, compared the mean between the cultivates, and by mean number of s-shoot collected 30 days after to sow and length spikes the mean had difference signification in level of 5 %, by Tukey test. Went made prediction of all variables, spatial dependence or independence, to places no sampled by kriging technical and begot contour maps. There was spatial correlation negative and positive between variables, with correlation range of 200 till 700 m.
Este trabalho teve por objetivo estudar e modelar a variabilidade espacial de variáveis referentes ao desenvolvimento do trigo cultivado no ano de 2003 em área de 22,62 ha pertencente à Cooperativa Central de Pesquisa Agrícola (COODETEC). Foram utilizadas cultivares CD 101 (3,52 ha) e CD 103 (18,10 ha). As amostragens foram em grade de 50 x 50 m, totalizando 89 pontos, a unidades de análise um quadrado de 0,25 m2. Foram obtidos dados de emergência de plântulas, número de perfilho, altura de plantas, número de espigas, comprimento de espigas, número de grãos por espiga, peso de mil sementes e produtividade. A dependência espacial foi mais evidente para o número médio de perfilhos por planta coletado 60 dias após a semeadura (DAS) e para a altura de plantas na colheita do trigo. Nas variáveis relacionadas com a espiga do trigo e os dados do número médio de perfilhos por planta 30 dias após semeadura não identificou-se dependência espacial. As demais variáveis foram consideradas espacialmente dependentes. Para as variáveis consideradas independentes espacialmente, comparou-se a média entre as cultivares, o número médio de perfilhos aos 30 DAS e o comprimento da espiga apresentaram médias significativamente diferentes ao nível de 5 % de significância pelo teste de Tukey. Estimou-se os valores das variáveis para locais não amostrados pela técnica da krigagem e foram gerados mapas de contorno, para as variáveis consideradas espacialmente dependentes ou independentes.Houve correlações espaciais negativas e positivas entre as variáveis consideradas, com alcances de correlação de 200 a 700 m.
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Hazim, Ossama. "A generalized rule-based short-term load forecasting technique." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/41942.
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A newly-developed technique for short-term load forecasting is generalized. The algorithm
combines features from knowledge-based and statistical techniques. The technique is
based on a generalized model for the weather-load relationship, which makes it site independent.
Weather variables are investigated, and their relative effect on the load is
reported. That effect is modeled via a set of parameters and rules that constitute the rule based
technique. This technique is very close to the intuitive judgmental approach an
operator would use to make his guess of the load. That is why it provides a systematic
way for operator intervention if necessary. This property makes the technique especially
suitable for application in conjunction with demand side management (DSM) programs.
Moreover, the algorithm uses pairwise comparison to quantify the categorical variables,
and then utilizes regression to obtain the least-square estimation of the load. Because it
uses the pairwise comparison technique, it is fairly robust. Since the forecast does not
depend on any preset model, the technique is inherently updatable. A generalized version
of the technique has been tested using data from four different sites in Virginia,
Massachusetts, Florida and Washington. The average absolute weekday forecast errors
range from 1.30% to 3.10% over all four seasons in a year. Error distributions show that
the errors are 5% or less around 91 % of the time.
Master of Science
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Landrein, Benoit. "Caractérisation du lien entre croissance et patterning dans la morphogenèse chez Arabidopsis." Thesis, Lyon, École normale supérieure, 2014. http://www.theses.fr/2014ENSL0884.
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Le contrôle moléculaire du patterning au cours des processus développementaux est aujourd’hui bien décrit chez les organismes multicellulaires. A l’inverse, la contribution de la croissance dans l’émergence des patterns reste peu explorée, et est souvent réduite à un rôle passif. Au cours de cette thèse, j’ai étudié cette question en utilisant le méristème apical caulinaire (MAC) d’Arabidopsis comme modèle. Le méristème est un groupe de cellules en divisions situé à l’extrémité de toutes les tiges et les branches et qui génère tous les organes aériens de la plante selon un patron stéréotypé, aussi appelé phyllotaxie. Dans une première partie, j’ai étudié comment la croissance de la tige pouvait influencer le patron phyllotactique. Plus précisément, en découplant dépôt de la cellulose dans la paroi et l’orientation des microtubules, j’ai montré que le patron de phyllotaxie devenait bimodal en raison de l’induction d’une torsion lors de la croissance de la tige. Dans une seconde partie, j’ai analysé le lien entre forme du MAC et expression génétique. En particulier, j’ai pu corréler l’expression d’un gène maître : SHOOTMERISTEM LESS (STM) au degré de courbure dans le MAC. De plus, en utilisant des approches de micromécaniques, j’ai aussi pu montrer que l’expression de STM pouvait être induite par le patron de contraintes localement généré par la courbure. Pour finir, j’ai aussi étudié comment la taille du méristème influence la robustesse du pattern de phyllotaxie sur la tige en modulant la fréquence d’initiation des organes. L’ensemble de ce travail met ainsi en avant le rôle de la croissance dans le patterning, notamment via des mécanismes de rétrocontrôles géométriques et mécaniquesThe molecular mechanisms behind the emergence of patterns during developmental processes have been well described in multicellular organisms. However, the contribution of growth in patterning is still poorly understood; growth is often seen as a passive output of the activity of the patterning signals. In this PhD, I have studied the relation between growth and patterning using the shoot apical meristem of Arabidopsis as a model system. The meristem is a group of dividing cells located at the tip of every stems and branches that generates all the aerial organs of the plant following a typical spatio-temporal pattern also called phyllotaxis. In a first part, the influence of post-meristematic growth on phyllotaxis was assessed. More precisely, by uncoupling cellulose deposition from the orientation of the microtubule array, I showed that the resulting stem torsion induces the emergence of a new and robust bimodal phyllotactic pattern. In a second part, the relation between meristem shape and gene expression was analyzed. More precisely, I correlated the expression of a master regulatory gene: SHOOT MERISTEMLESS (STM) to tissue curvature in the boundary domain that separates the emerging organ from the meristem. Furthermore, I showed that STM expression can be induced by micromechanical perturbations thus suggesting that shape-derived mechanical stresses in the meristem boundary contribute to STM expression. Finally, I also studied how meristem size can influence the robustness of the pattern of phyllotaxis along the stem through a modulation of the frequency of organ initiation. Altogether, this work highlights the important contribution of growth in patterning, notably thanks to the existence of geometrical and mechanical feedbacks