• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 12
  • 10
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 47
  • 47
  • 14
  • 13
  • 8
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 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.
31

A Framework for Modelling Species-Specific Site Quality Index Based on Data Generated From Remote Sensing Imagery and a Process-Based Model

Quazi K., Hassan January 2008 (has links)
This Thesis presents a framework for modelling species-specific site quality index (SQI) at a spatial resolution of 250 m by integrating biophysical variables of growing degree days (GDD), soil water content (SWC), and incident photosynthetically active radiation (PAR) in descriptions of potential tree growth. Development of GDD maps is based on processing and blending remotely-sensed data acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra satellite and ETM+ sensor on Landsat-7 satellite at spatial resolutions of 250 m and 28.5 m. Descriptions of SWC are based on a temperature-vegetation wetness index (TVWI) that relies on MODIS-based optical and thermal image products. PAR is estimated with an existing solar-radiation distribution model. SQI is defined as a function of species vital attributes and species environmental response to GDD, TVWI, and PAR. The methods are applied to a balsam fir [bF; Abies balsamea (L.) Mill.] dominated region in northwest New Brunswick. Comparisons between SQI and field-based estimates of site index and enhanced vegetation index showed that about 66 and 88% of the values corresponding to a series of Forest Development Survey lines (691 in total) were within 16% of SQI values. On average 92.1% of high bF-content stands (> 50% composition) in the area fell on medium-to-very high SQI values (> 0.50). Based on these agreements, SQI can be perceived as a good predictor of potential tree-species growth in the selection of optimal sites for biomass and wood fibre production.
32

Desempenho agronomico de cana-de-açucar em Jaguari - RS / Agronomic perfomance of sugarcane in Jaguari - RS

Morais, Katiule Pereira 29 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Currently the state of Rio Grande do Sul (RS) the cultivation of sugar cane is being encouraged for bioenergy. However, there is a lack of information on the performance of agricultural and industrial modern genotypes at conditions of RS. In order to evaluate the growth, development and quality of genotypes of sugar cane cultivation of sugarcane plant (2009/2010) and cane ratoon first year (2010/2011) an experiment was conducted in the municipality of Jaguari Central Depression of RS. The experimental design was randomized blocks with three replications. We evaluated 12 genotypes of 13 early and medium maturity / delayed a total of 25 materials, all of RIDESA. The evaluations were phyllochron, final leaf number on main stem height, leaf area, straw yield and agronomic and qualitative parameters. The phyllochron values between genotypes showed little variation, but the genotypes RB966229, RB947625 and RB008347 significant difference in relation to the cane plant and ratoon cane. The NFT showed no difference between the early-maturing genotypes, only cycle between the mid / late, and some genotypes of mid / late show higher NFT in sugarcane ratoon. The height growth was comprised of three distinct phases for all genotypes, starting with a slow growth after the phase of higher growth and finally there was a decrease in growth due to the start of the maturation process. The leaf area showed a growth pattern similar to the stem, but the last stage corresponded to a decrease in AF. The average yield of stalks of more productive genotypes in early-maturing crops of sugar cane plant and ratoon cane (96.6 and 123.4 TCH) was similar to that obtained with the most productive genotypes cycle mid / late (101.5 TCH and 128.0), with higher productivity in the cultivation of sugarcane ratoon. The genotype RB965911 RB925345 and early-maturing genotypes and RB925268, RB975019 RB987935 cycle and medium / late show qualitative variables, maturation rate and productivity of stem indicate that these genotypes as a high potential for the central region of the RS. / Atualmente no estado do Rio Grande do Sul (RS) o cultivo da cana-de-açúcar está sendo incentivado para fins bioenergéticos. No entanto, existe a carência de informações sobre o desempenho agrícola e industrial de genótipos modernos nas condições edafoclimáticas do RS. Com o objetivo de avaliar o crescimento, desenvolvimento e qualidade de genótipos de cana-de-açúcar em cultivo de cana-planta (2009⁄2010) e de cana-soca de primeiro ano (2010⁄2011) foi realizado um experimento no município de Jaguari, Depressão Central do RS. O delineamento experimental foi o blocos ao acaso com três repetições. Foram avaliados 12 genótipos de ciclo precoce e 13 de ciclo médio⁄tardio, totalizando 25 materiais, todos da RIDESA. As avaliações realizadas foram filocrono, número final de folhas na haste principal, estatura, área foliar, produção de colmos e parâmetros agronômicos e qualitativos. Os valores de filocrono entre os genótipos tiveram uma pequena variação, porém os genótipos RB966229, RB947625 e RB008347 apresentaram diferença significativa em relação à canaplanta e cana-soca. O NFT não apresentou diferença entre os genótipos de ciclo precoce, somente entre os de ciclo médio⁄tardio, sendo que alguns genótipos de ciclo médio⁄tardio apresentam maior NFT em cana-soca. O crescimento em estatura compreendeu três fases distintas para todos os genótipos, iniciando-se por um crescimento lento, após a fase de maior crescimento e por fim ocorreu uma diminuição do crescimento em função do inicio do processo de maturação. A área foliar apresentou um padrão de crescimento similar ao do colmo, porém a última etapa correspondeu ao decréscimo da AF. A produtividade média de colmos dos genótipos mais produtivos de ciclo precoce nos cultivos de cana-planta e canasoca (96,6 e 123,4 TCH) foi semelhante aquela obtida com os genótipos mais produtivos de ciclo médio/tardio (101,5 e 128,0 TCH), com maior produtividade no cultivo de cana-soca. O genótipo RB965911 e RB925345 de ciclo precoce e os genótipos RB925268, RB975019 e RB987935 de ciclo médio/tardio apresentam variáveis qualitativas, índice de maturação e produtividade de colmos que indicam esses genótipos como sendo os de maior potencial para a região central do RS.
33

Desenvolvimento e maturidade fisiolÃgica de manga âtommy atkinsâ no vale do SÃo Francisco / Physiological maturity and development and manga (Mangifera indica), cv. Tommy Atkins, in the valley of the San Francisco

Eliseu MarlÃnio Pereira de Lucena 16 November 2006 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O presente trabalho objetivou caracterizar as alteraÃÃes fÃsicas, fÃsico-quÃmicas, quÃmicas e bioquÃmicas durante o crescimento dos frutos de mangueira (Mangifera indica), cv. Tommy Atkins, da antese atà a colheita comercial, visando à definiÃÃo do ponto de colheita ideal em unidades de calor. Os frutos foram colhidos aos 35, 49, 63, 70, 77, 84, 91, 98, 105 e 112 dias apÃs a antese (DAA), sendo feitas as seguintes determinaÃÃes: aspectos morfolÃgicos externos; diÃmetros longitudinal, ventral e transversal; produto dos diÃmetros; massas fresca, seca e de Ãgua; teor de Ãgua; escalas de coloraÃÃo da casca, de Blush para coloraÃÃo da casca e de coloraÃÃo da polpa; luminosidade, croma e Ãngulo Hue da polpa; firmeza; unidades de calor (UC); sÃlidos solÃveis totais (SST); acidez total titulÃvel (ATT); pH; relaÃÃo SST/ATT; amido; aÃÃcares solÃveis totais, redutores e nÃo redutores; nitrogÃnio total, nÃo protÃico e protÃico; proteÃnas bruta e verdadeira; vitamina C; clorofila e carotenÃides totais; fenÃlicos polimÃricos, oligomÃricos e dimÃricos; pectinas total, solÃvel, de alta metoxilaÃÃo e de baixa metoxilaÃÃo; protopectina; percentagem de solubilizaÃÃo de pectina; atividade das enzimas pectinametilesterase, poligalacturonase, polifenoloxidase, peroxidase, amilase total, &#945;- e &#946;-amilases, &#945;- e &#946;-galactosidases extraÃdas de citosol e de parede celular; proteÃnas extraÃdas de citosol e de parede celular. O trabalho indicou que as mangas âTommy Atkinsâ atingiram a maturidade fisiolÃgica aos 98 DAA, que equivale a 1.685,09 UC. O croma da polpa foi o melhor indicador do estÃdio de desenvolvimento do fruto da mangueira cultivada sob irrigaÃÃo no sub-mÃdio SÃo Francisco, considerando-se o seu alto coeficiente de determinaÃÃo, R2=0,9832 (P < 0,01) e seu alto coeficiente de correlaÃÃo com pH, aÃÃcares solÃveis totais e carotenÃides totais, R=0,95; 0,93; e 0,93, respectivamente (P < 0,01). / The objective of this work was to characterize the physical, physicochemical, chemical and biochemical changes during the development of mango (Mangifera indica), cv. Tommy Atkins from anthesis to harvest, identifying the optimum harvest maturity stage in heat units. The fruits were harvested at 35, 49, 63, 70, 77, 84, 91, 98, 105 and 112 days after the anthesis (DAA), being made the following determinations: fruit external morphology; longitudinal, ventral e transverse diameters; product of the diameters; fresh and dry mass; water content and percentage; skin, Blush skin and pulp color scales; pulp luminosity, Hue angle and chroma; firmness; heat units (HU); total soluble solids (TSS); total titratable acidity (TTA); pH; TSS/TTA ratio; starch; total, reducing and nonreducing soluble sugars; total, protein and nonprotein nitrogen; crude and true protein; C vitamin; total chlorophyll and carotenoids; polymeric, oligomeric and dimeric phenolics; pectin total, soluble and high/low metoxilation degree; protopectin; solubilization pectin percentage; pectin metyhylesterase, poligalacturonase, polyphenol oxidase, peroxidase, total amylase, &#945;- and &#946;-amylases, &#945;- and &#946;-galactosidases enzymes activities; cell wall and cytosol proteins. This work has indicated that mango âTommy Atkinsâ reached the physiological maturity at 98 DAA, that is equivalent to 1.685,09 HU. The pulp chroma was the best fruit development stage indicator in the cultivated conditions of this study (SÃo Francisco valley), taking into account the high coefficient of determination, R2=0,9832 (P < 0,01) and excellent correlation coefficients with pH, total soluble sugars and total carotenoids, R=0,95; 0,93; e 0,93, respectively (P < 0,01).
34

Energiutvärdering av Undervisningshuset på Kungliga Tekniska Högskolan i Stockholm : Uppföljning av energianvändning medelst normalårskorrigering / Energy evaluation of Undervisningshuset at The Royal Institute of Technology in Stockholm : Follow-up of energy use by means of standard year correction

Pehrs, Malin, Hjort, Lina January 2020 (has links)
Bostad- och servicesektorn står för cirka 40 % av den totala årliga energianvändningen i Sverige. För nybyggda hus med ambitiösa miljökrav, såsom objektet för denna studie, är en viktig del i hållbarhetsarbetet uppföljning och feedback av energianvändningen för att illustrera sambandet mellan ambition och faktiskt resultat. Energiuppföljning i Undervisningshuset, en byggnad på KTH Campus med ambitiösa visioner om hållbarhet och pedagogik, är därför syftet med denna studie. För att jämföra energianvändningen mellan olika år måste energianvändningen normaliseras vilket sker i två steg; korrigering för normalt brukande och normalårskorrigering. I denna rapport beräknas Undervisningshusets normaliserade energianvändning medelst energisignatur och graddagar, vilken jämförs med den enligt Energideklarationen förväntade energianvändningen som normaliserats med SMHI:s energi-index. Undervisningshusets energiprestanda är enligt energisignaturmetoden 56 kWh/m2 och år och enligt graddagsmetoden 59 kWh/m2 och år, jämfört med den förväntade energiprestandan i Energideklarationen på 60 kWh/m2 och år. Både resultaten för denna rapport och Energideklarationen klassificerar därmed Undervisningshuset med Energiklass B. / The housing- and service sector makes up about 40 % of the total yearly energy use in Sweden. For new buildings with ambitious requirements, such as the object of this study, an important part of the work towards sustainability is follow-up and feedback on its energy use to illustrate the connection between ambition and actual result. Energy follow-up for Undervisningshuset, a building on KTH Campus with ambitious visions of sustainability and pedagogy, is therefore the aim of this study. To compare the energy use in buildings between different years the energy use must be normalized which is done in two steps; correction for normal occupancy and standard year correction. In this report the normalized energy use of Undervisningshuset is calculated by means of energy signature and degree-days, which is compared to the expected energy use according to the Energy Declaration normalized by SMHI’s energy-index. The energy performance of Undervisningshuset is 56 kWh/m2 and year according to the energy signature method and 59 kWh/m2 according to the degree-day method, compared to the expected energy performance in the Energy Declaration of 60 kWh/m2 and year. Both the results of this report and the Energy Declaration thereby classifies Undervisninshuset with Energy Class B.
35

Food webs and phenology models: evaluating the efficacy of ecologically based insect pest management in different agroecosystems

Philips, Christopher Robin 02 September 2013 (has links)
Integrated pest management (IPM) is defined as an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices. Integrated pest management programs use current, comprehensive information on the life cycles of pests and their interactions with host plants and the environment. This information, in combination with available pest control methods, is used to manage pest populations by the most economical means, and with the least possible hazard to people, property, and the environment. True IPM takes advantage of all appropriate pest management options including, as appropriate, the judicious use of pesticides. It is currently estimated the IPM in its full capacity is being practiced on less than ten percent of the agricultural land in the U.S. The primary objective of this research was to evaluate land management decisions and create new tools to promote a true IPM approach and encourage growers to reevaluate their method of insect control. To accomplish this I developed new predictive tools to reduce or eliminate unnecessary insecticide application intended to target cereal leaf beetle in wheat, and assessed a conservation biological control technique, farmscaping, to determine its true impact on lepidopteran pest suppression in collards. / Ph. D.
36

Characterization of Fruit Development and Ripening of Vaccinium angustifolium Ait. in Relation to Microclimate Conditions

Gibson, Lara Dawn 09 November 2011 (has links)
Berry ripening in lowbush blueberry (Vaccinium angustifolium Ait.) is influenced by developmental, physiological and climatic factors resulting in a heterogenous mix of maturities at harvest. This study characterizes the physico-chemical changes which occur during fruit ontogeny and links ripening patterns to micoclimate. Individual clones in five commercial fiels were followed in the 2006 and 2007 growing seasons. Phenolic acids, flavonols, and flavan-3-ols decreased and anthocyanins increased with maturity. Peak maturity consistently occurred at 1200 accumulated growing degree days (GDD). There was a sharp decline in fruit retention at the end of the growing season suggesting a date after which harvested yield declines but no consistent pattern was detected between years or fields.The consistency of GDD accumulation in relation to ripening pattern suggests GDDs can be used as a predictive ripening index. The physico-chemical nature of ripe berries indicates ripe berries could be harvested earlier than is currently the practice.
37

Using a logistic phenology model with improved degree-day accumulators to forecast emergence of pest grasshoppers

Irvine, Paul Michael January 2011 (has links)
Many organisms, especially animals like insects, which depend on the environment for body heat, have growth stages and life cycles that are highly dependent on temperature. To better understand and model how insect life history events progress, for example in the emergence and initial growth of the biogeographical research subjects, we must first understand he relationship between temperature, heat accumulation, and subsequent development. The measure of the integration of heat over time, usually referred to as degree-days, is a widely used science-based method of forecasting, that quantifies heat accumulation based on measured ambient temperature. Some popular methods for calculation of degreedays are the traditional sinusoidal method and the average method. The average method uses only the average of the daily maximum and minimum temperature, and has the advantage that it is very easy to use. However, this simplest method can underestimate the amount of degree-day accumulation that is occurring in the environment of interest, and thus has a greater potential to reduce the accuracy of forecasting insect pest emergence. The sinusoidal method was popularized by Allen (1976, [1]), and gives a better approximation to the actual accumulation of degree-days. Both of these degree-day accumulators are independent of typical heating and cooling patterns during a typical day cycle. To address possible non-symmetrical effect, it was deemed prudent to construct degree-day accumulators to take into account phenomena like sunrise, sunset, and solar noon. Consideration of these temporal factors eliminated the assumption that heating and cooling in a typical day during the growth season is symmetric. In some tested cases, these newer degree-day integrators are more accurate than the traditional sinusoidal method, and in all tested cases, these integrators are more accurate than the average method. After developing the newer degree-day accumulators, we chose to investigate use of a logistic phenology model similar to one used by Onsager and Kemp (1986, [54]) when studying grasshopper development. One reason for studying this model is that it has parameters that are important when considering pest management tactics, such as the required degree-day accumulations needed for insects in immature stages (instars) to be completed, as well as a parameter related to the variability of the grasshopper population. Onsager and Kemp used a nonlinear regression algorithm to find parameters for the model. I constructed a simplex algorithm and studied the effectiveness when searching for parameters for a multi-stage insect population model. While investigating the simplex algorithm, it was found that initial values of parameters for constructing the simplex played a crucial role in obtaining realistic and biologically meaningful parameters from the nonlinear regression. Also, while analyzing this downhill simplex method for finding parameters, it was found there is the potential for the simplex to get trapped in many local minima, and thus produce extraneous or incorrectly fitted parameter estimates, although Onsager and Kemp did not mention this problem. In tests of my methods of fitting, I used an example of daily weather data from Onefour, AB, with a development threshold of 12 ±C and a biofix day of April 1st, as an example. The method could be applied to larger, more extensive datasets that include grasshopper population data on numbers per stage, by date, linked to degree accumulations based on the non-symmetrical method, to determine whether it would offer significant improvement in forecasting accuracy of spring insect pest events, over the long term. / xii, 106 leaves ; 29 cm
38

Floral induction and initiation in Ptilotus nobilis: The effect of light intensity, temperature and daylength on floral evocation and development.

Sybille Orzek Unknown Date (has links)
Ptilotus nobilis is a short-lived perennial wildflower, native to semi-arid and arid areas of Australia. Propagation by vegetative means is constrained by the early onset and a continuous flowering habit. Despite being defined as the main barrier for vegetative propagation no published research on floral induction and initiation was found. The aim of this study is to provide the first insights into floral evocation in P. nobilis, with the general objectives being to investigate floral induction and initiation, find the means to maintain plants in the vegetative phase, enhance leaf initiation and to gain knowledge of growth and development with an emphasis on light intensity, temperature and daylength. Early experiments aimed to increase the understanding of growth and development. The main cardinal events were identified including the onset of branching (axillary stem growth), visible bud stage, first floret opening and maturity of the inflorescence. To aid future cultivation schedules, four growing degree days (GDD) and one chronological model, using days after sowing (DAS), were established and validated. All GDD models were accurate in predicting first floret opening and maturity, but not in predicting visible bud stage. Best prediction was achieved by using an upper temperature threshold of 18.2 ºC and an own base temperature of 5.0 ºC. Days after sowing were an accurate means of prediction, indicating that temperature and other variables such as light intensity regulate development. A series of defoliation treatments investigated the maintenance of P. nobilis plants in the vegetative phase. Within all treatments, reproductive structures were observed and all plants with more than two true leaves entered the reproductive phase. Plants with less than two true leaves showed a delayed floral bud appearance by up to 20 days. Floral development was affected by most defoliation treatments resulting in vegetative growth within the inflorescences. It is hypothesized that plants have a very short juvenile phase and that a constant floral stimulus may be needed for floral evocation. Using scanning electron and light microscopy a template for the transition from vegetative to reproductive phase was developed. Bract initiation was accompanied by a significant increase in meristem area and diameter, and was defined as the onset of flowering. The established template was used in a subsequent glasshouse trial, which revealed that floral initiation occurred very early and at 25 DAS all plants had entered the reproductive phase. Branching and leaf area expansion were identified as post- initiation processes. Plants were exposed to different light intensities (229.3, 398.6 and 909.3 µmol m-2 s-1) in a glasshouse. Under low light, final leaf number increased by up to three leaves, indicating that the vegetative phase was prolonged. Cardinal events were delayed but all plants reached maturity. It was concluded that a light intensity of 229.3 µmol m-2 s-1 was not low enough to prevent floral initiation and that a further decrease of light intensity in combination with temperature could be more effective. Interactions of light intensity, temperature and daylength were investigated. Plants were grown under high light and low light (< 1.2 MJ m-2) intensities, 25/10 ºC and 35/20 ºC and daylengths of 11 h and 16 h. During the trial period (42 days), low light intensity suppressed floral initiation and high temperatures maintained more plants (70%) in the vegetative phase. However daylength treatments had no effect on the time of bract initiation or the percentage of vegetative plants. After 83 days floral buds and axillary stems were observed on some plants under low light intensity, indicating the onset of the reproductive phase and showing that P. nobilis could not be maintained in the vegetative phase indefinitely. Plants under high light were harvested at maturity and effects of temperature and daylength were analysed. Final leaf number increased under 35/20 ºC supporting the previously established results that floral initiation was delayed and leaf production enhanced by high temperature. Morphological data was collected to classify the photoperiodic response of P. nobilis. Plants under 25/10 ºC and 11 h had the longest inflorescences and greatest number of buds and flowers, which was also reflected in the buds and flowers dry weight, with an increase of up to 3.4 fold under these conditions. The difficulty of classifying some plants accordingly to their photoperiodic response and the proposal that P. nobilis may be a facultative short day plant under 25/10 ºC is discussed. In summary, this study presents the first evidence that P. nobilis has a very short juvenile phase and that growth and development are mainly driven by light intensity and temperature. It was possible to enhance vegetative growth by defoliation, low light intensity and high temperatures, however this did not fully prevent flowering, which indicates that P. nobilis has a very strong flowering response or signal.
39

Floral induction and initiation in Ptilotus nobilis: The effect of light intensity, temperature and daylength on floral evocation and development.

Sybille Orzek Unknown Date (has links)
Ptilotus nobilis is a short-lived perennial wildflower, native to semi-arid and arid areas of Australia. Propagation by vegetative means is constrained by the early onset and a continuous flowering habit. Despite being defined as the main barrier for vegetative propagation no published research on floral induction and initiation was found. The aim of this study is to provide the first insights into floral evocation in P. nobilis, with the general objectives being to investigate floral induction and initiation, find the means to maintain plants in the vegetative phase, enhance leaf initiation and to gain knowledge of growth and development with an emphasis on light intensity, temperature and daylength. Early experiments aimed to increase the understanding of growth and development. The main cardinal events were identified including the onset of branching (axillary stem growth), visible bud stage, first floret opening and maturity of the inflorescence. To aid future cultivation schedules, four growing degree days (GDD) and one chronological model, using days after sowing (DAS), were established and validated. All GDD models were accurate in predicting first floret opening and maturity, but not in predicting visible bud stage. Best prediction was achieved by using an upper temperature threshold of 18.2 ºC and an own base temperature of 5.0 ºC. Days after sowing were an accurate means of prediction, indicating that temperature and other variables such as light intensity regulate development. A series of defoliation treatments investigated the maintenance of P. nobilis plants in the vegetative phase. Within all treatments, reproductive structures were observed and all plants with more than two true leaves entered the reproductive phase. Plants with less than two true leaves showed a delayed floral bud appearance by up to 20 days. Floral development was affected by most defoliation treatments resulting in vegetative growth within the inflorescences. It is hypothesized that plants have a very short juvenile phase and that a constant floral stimulus may be needed for floral evocation. Using scanning electron and light microscopy a template for the transition from vegetative to reproductive phase was developed. Bract initiation was accompanied by a significant increase in meristem area and diameter, and was defined as the onset of flowering. The established template was used in a subsequent glasshouse trial, which revealed that floral initiation occurred very early and at 25 DAS all plants had entered the reproductive phase. Branching and leaf area expansion were identified as post- initiation processes. Plants were exposed to different light intensities (229.3, 398.6 and 909.3 µmol m-2 s-1) in a glasshouse. Under low light, final leaf number increased by up to three leaves, indicating that the vegetative phase was prolonged. Cardinal events were delayed but all plants reached maturity. It was concluded that a light intensity of 229.3 µmol m-2 s-1 was not low enough to prevent floral initiation and that a further decrease of light intensity in combination with temperature could be more effective. Interactions of light intensity, temperature and daylength were investigated. Plants were grown under high light and low light (< 1.2 MJ m-2) intensities, 25/10 ºC and 35/20 ºC and daylengths of 11 h and 16 h. During the trial period (42 days), low light intensity suppressed floral initiation and high temperatures maintained more plants (70%) in the vegetative phase. However daylength treatments had no effect on the time of bract initiation or the percentage of vegetative plants. After 83 days floral buds and axillary stems were observed on some plants under low light intensity, indicating the onset of the reproductive phase and showing that P. nobilis could not be maintained in the vegetative phase indefinitely. Plants under high light were harvested at maturity and effects of temperature and daylength were analysed. Final leaf number increased under 35/20 ºC supporting the previously established results that floral initiation was delayed and leaf production enhanced by high temperature. Morphological data was collected to classify the photoperiodic response of P. nobilis. Plants under 25/10 ºC and 11 h had the longest inflorescences and greatest number of buds and flowers, which was also reflected in the buds and flowers dry weight, with an increase of up to 3.4 fold under these conditions. The difficulty of classifying some plants accordingly to their photoperiodic response and the proposal that P. nobilis may be a facultative short day plant under 25/10 ºC is discussed. In summary, this study presents the first evidence that P. nobilis has a very short juvenile phase and that growth and development are mainly driven by light intensity and temperature. It was possible to enhance vegetative growth by defoliation, low light intensity and high temperatures, however this did not fully prevent flowering, which indicates that P. nobilis has a very strong flowering response or signal.
40

Seasonal Aggregations of the Florida Manatee (Trichechus manatus latirostris) in the Port Everglades and Intracoastal Regions of Fort Lauderdale, Florida.

Goldman, Jaime M. 01 December 2010 (has links)
The Florida manatee (Trichechus manatus latirostris), a subspecies of the West Indian manatee, is one of the most endangered marine mammals in United States waters. The Florida manatee is the only manatee that ranges into subtropical and temperate regions. During the winter months manatees adopt a “refuging strategy” where they aggregate at warm-water sources immediately following decreases in the ambient water temperature to below 20° C (68° F) in order to avoid cold stress syndrome (CSS). During the winter manatees aggregate in warm water refuges, including natural warm water springs and the effluent discharges of power plants. The purpose of this study was to determine the number of manatees that aggregate and utilize the waters of the Florida Power and Light (FPL) Plant in Port Everglades (PPE), Florida, its effluent canal, and the surrounding Intracoastal Waterway during the winter months. This study documents the importance of Port Everglades as a wintering refuge for the Florida manatee. This study analyzed the inverse relationship between the number of manatees present at a warm water effluent and water temperature. In this study data were collected over five manatee winter seasons (between 15 November and 31 March) from 1999-2004, from both boat-based and land-based surveys monitoring the presence of manatees in the effluent canal from the FPL electricity generating facility in Port Everglades, FL and the Intracoastal Waterway. Findings indicated that there was an inverse relationship between the number of manatees present and water temperature, where more manatees were present in cooler months, and fewer in warmer months. This study also analyzed the parameters of Catch per Unit Effort (CPUE) as well as heating degree-days and their effect on and relationship to the number of manatees present. The higher the heating degree-days number, the more severe, or cold, winter this indicates. The year with the highest heating degree-days, 24.98, was the 2002-2003 season, which was also the season with the highest number of manatees observed, 393, and the highest CPUE, 10.62 manatees/day.

Page generated in 0.0595 seconds