950 resultados para huntsmen, archers, deer, trees, flowers


Relevância:

20.00% 20.00%

Publicador:

Resumo:

SHORT-TERM EFFECTS OF SALINITY ON SOME PHYSIOLOGICAL PARAMETERS OF YOUNG OLIVE TREES OF ARBEQUINA, COBRANÇOSA AND GALEGA VARIETIES Ana Elisa Rato1,4, Renato Coelho1, Margarida Vaz1, Teresa Carola2, Dália Barbosa2, Nádia Silva1, José dos Santos2, Lourenço Machado2, João Godinho2, Luzia Ruas2, Margarida Barradas2, Hernani Pereira2, Sara Porfírio4 1 ICAAM, Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal 2 Master students, Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal 3 Ph.D. student, Universidade de Évora, Apartado 94, 7002-554 Évora, Portugal 4 aerato@uevora.pt Due to the desertification in some regions, the interest in plant’s tolerance to salinity has been increasing, as this response is determining for plant survival in stress conditions. This work reports the investigation of tolerance to salt in two year-old olive trees (Olea europaea L.) of three varieties, Arbequina, Cobrançosa and Galega vulgar. Plants were grown in 10 L plastic pots containing approximately 9 Kg of a sandy granitic soil, on a greenhouse. For 3 months (from the beginning of February to the end of April 2012), they were subjected to three levels of salinity in the irrigation water, 0 mM, 80 mM and 200 mM NaCl (6 plants per salinity level in a total of 18 plants of each variety),. Stomatal conductance (gs) and relative leaf chlorophyll content were assessed on each plant in February, March and April. Mid-day leaf water potential () and soil salinity were measured at the end of the experiment (April). On average, concerning all treatments and dates of determination, stomatal conductance of Arbequina and Galega vulgar was quite similar, around 40 mmol m-2 s-1, but Cobrançosa had a value of gs 36% higher, almost 50% higher (61 mmol m-2 s-1) when compared with the controls (0 mM salt) of the other two varieties. In percentage of controls, there was little difference in gs between varieties and between salinities during February and March. In contrast, in April, after about 90 days of exposure to salt, there was a clear decrease in gs with salt irrigation, proportional to salt concentration. Compared with controls, plants irrigated with 200 mM salt showed around 80% (Arbequina) or 85% (Cobrançosa and Galega vulgar) decrease in gs. Chlorophyll content of leaves showed less than 5% difference between varieties on the average of all treatments and dates of determination. During the course of this experiment, the salinity levels used did not show any relevant effect on chlorophyll content. Overall, at the end of the experimental period (April), leaf water potential () at midday was significantly higher in Cobrançosa (-1,4 MPa) than in Galega vulgar (-1,7 MPa) or Arbequina (-1,8 MPa), and salt decreased  of control plants (-1,25 MPa) by an average 30% (with 80 mM) and 65% (with 200 mM). At the end of the experiment, salinity in the soil irrigated with 0 mM, 80 mM or 200 mM NaCl was, on average of all varieties, 0,2 mS, 1,0 mS or 2,0 mS, respectively. Soil salinity was quite similar in Arbequina and Galega vulgar but about 35% lower in the pots of Cobrançosa, on average of all salt-irrigation levels. Plants of Cobrançosa had higher stomatal conductance, however they showed higher water potential and lower salinity in the soil. These apparently contradictory results seem to suggest that Cobrançosa responds to salt differently from the other two varieties. This issue needs further investigation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Soil salinization is a problem in the Mediterranean region. This paper reports a research on the response to salt in two year-old olive trees (Olea europaea L.) of three Iberian varieties: Arbequina, Cobrançosa and Galega Vulgar. Plants were grown in plastic pots containing approximately 9 Kg of a sandy granitic soil, on a greenhouse at the University of Évora since February 2010. The experiment went from February to April 2012. As a rule, plants were watered every other day alternating salt solution (0 mM, 80 mM or 200 mM NaCl) or tap water. After three months irrigation with the different NaCl solutions, soil electric conductivity and soil water content were significantly higher on salt-irrigated pots. Salt also decreased significantly stomatal conductance (gs) and mid-day leaf water potential (), Cobrançosa having in general higher gs and but lower SLA than the two other varieties. Chlorophyll content of leaves was not affected by salt after this three months exposure to NaCl but was significantly higher on Arbequina and lower on Cobrançosa. In general, hyperspectral reflectance indexes did not show significant correlations with salt irrigation, except for the Photochemical Reflectance Index (PRI) which was clearly lower on plants of all three varieties irrigated with salt. Interestingly, Cobrançosa showed frequently vegetation indexes different from the other two varieties.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Dada a extrema importância económica e ambiental que o montado de sobro tem em Portugal, e dado o declínio deste devido a várias razões (e.g. doença, idade das plantas) é premente desenvolver estratégias de preservação de sobreiros elite e optimizar técnicas para a propagação destes genótipos. No primeiro Capítulo expõe-se uma breve introdução sobre o montado actual e as técnicas actuais de regeneração/propagação do sobreiro. Descreve-se ainda as principais técnicas de preservação e avaliação de estabilidade genética referidas na literatura para sobreiro e outras lenhosas. No Capítulo II é apresentado um estudo de melhoramento das condições actuais de maturação de embriões somáticos de sobreiro com vista a aperfeiçoar o processo de conversão em plantas. Neste capítulo é apresentado um protocolo melhorado em relação ao actual que permite um desenvolvimento dos embriões somáticos dum modo semelhante aos embriões zigóticos em termos de substâncias de reserva. O Capítulo III mostra um estudo efectuado com o objectivo principal de avaliar estabilidade genética durante todo o processo de embriogénese somática. Neste capítulo são apresentados resultados duma análise feita por RAPD em fases distintas da embriogénese somática de sobreiro. Neste estudo mostra-se que não existem diferenças significativas entre plantas de campo, embriões somáticos e plantas regeneradas. No Capítulo VI, pretende-se complementar o estudo anterior. Neste Capítulo descreve-se a dinâmica do ciclo celular durante as primeiras fases de embriogénese somática na presença de reguladores de crescimento. Este trabalho permitiu concluir a importância dos reguladores de crescimento na indução e perceber o peso do factor genótipo durante o processo. Considerando os resultados anteriores, a necessidade de um processo eficiente de preservação de genótipos elite torna-se fundamental. No Capítulo V descreve-se um protocolo de criopreservação eficiente sem recursos a substâncias tóxicas. Nesta secção é ainda feita uma análise de variabilidade genética após criopreservação através de FCM, AFLP e SSR. Todos os resultados obtidos anteriormente são postos a prova no Capítulo VI onde se faz uma monitorização extensiva de 10 genótipos elite, tendo em conta a sua capacidade de produção de cortiça, através do processo de embriogénese somática. Durante esta secção são utilizados os protocolos desenvolvidos anteriormente e avaliados na sua eficiência. Neste capítulo é descrita a integração de vários segmentos deste estudo num só protocolo eficiente de regeneração e preservação de sobreiros através de embriogénese somática. Finalmente, no Capítulo VI são apresentadas as conclusões da presente Tese de Doutoramento, com especial incidência para linhas de investigação futuras a serem tomadas. Discute-se a importância deste novo protocolo na optimização da produção da cortiça e traçam-se possíveis aplicações alternativas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Durante o último século, as populações de cervídeos têm aumentado substancialmente um pouco por toda a Europa. O veado Cervus elaphus não foi exceção, apresentando atualmente uma ampla distribuição geográfica. Após a quase extinção de todas as populações selvagens desta espécie em Portugal, o número de efetivos de veado e a área de distribuição da espécie têm aumentado significativamente nas últimas décadas. Esta proliferação deveu-se fundamentalmente aos processos de reintrodução implementados em algumas zonas do país, como foi o caso da Serra da Lousã. Dez anos após a reintrodução, a expansão geográfica e demográfica é já uma realidade e a espécie assume um papel relevante tanto do ponto de vista cinegético como turístico. Com o aumento das populações de ungulados, surge a necessidade de aumentar o conhecimento existente sobre estas espécies, particularmente ao nível das estimativas populacionais, do uso e seleção de habitat, do comportamento e da fisiologia das populações. Neste sentido, um dos objetivos foi comparar quatro métodos de contagem de excrementos em termos de estimativa populacional, aplicabilidade e eficiência. Face aos resultados obtidos, o método de transectos lineares com distance sampling revelou-se o mais eficiente, providenciando uma boa precisão num menor tempo. Relativamente ao uso e seleção do habitat, recorrendo a transectos de contagem de excrementos e a observações diretas, verificou-se que o veado seleciona positivamente habitats que lhe proporcionam simultaneamente alimento e refúgio, como é o caso das áreas de ecótono. A preferência por áreas de ecótono evidencia um comportamento adaptativo de maximização de energia, no qual os animais optam por procurar refúgio na proximidade das áreas de alimentação de forma a minimizarem os dispêndios energéticos. Em termos de dinâmica populacional, verificou-se uma relação entre a densidade de veado e o tamanho dos seus grupos, bem como o efeito nos mesmos do coberto vegetal. Contudo, dado o seu alto dimorfismo sexual em termos de tamanho corporal, as preferências de habitat podem também ser em parte responsáveis pela segregação sexual fora da época de reprodução. Face aos resultados obtidos através do método de observação direta de animais, a segregação sexual surge como consequência da interação entre fatores sociais e de habitat, que resultam de diferentes estratégias reprodutivas por parte de ambos os sexos. As diferentes estratégias reprodutivas são também notórias em termos de condição física e imunológica, com os machos a aumentarem a sua condição durante as épocas de primavera e verão de forma a melhorarem a sua performance durante o cio, e as fêmeas a viverem grande parte do ano no limiar da condição física devido ao seu investimento na sobrevivência da sua descendência. Globalmente, o veado apresenta uma boa adaptação à Serra da Lousã e representa um importante recurso natural para esta região. Contudo, para que a proliferação desta população selvagem continue, é necessária a implementação de medidas de gestão adequadas a este ecossistema mediterrâneo.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The paper centres on a single document, the 1968 doctoral thesis of L Bruce Archer. It traces the author’s earlier publications and the sources that informed and inspired his thinking, as a way of understanding the trajectory of his ideas and the motivations for his work at the Royal College of Art from 1962. Analysis of the thesis suggests that Archer’s ambition for a rigorous ‘science of design’ inspired by algorithmic approaches was increasingly threatened with disruption by his experience of large, complex design projects. His attempts to deal with this problem are shown to involve a particular interpretation of cybernetics. The paper ends with Archer’s own retrospective view and a brief account of his dramatically changed opinions. Archer is located as both a theorist and someone intensely interested in the commercial world of industrial design.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Tese dout., Ciências Agrárias, Produção Vegetal, Unidade de Ciências e Tecnologias Agrárias, Universidade do Algarve, 2000

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This work aimed to assess how potassium (K) and nitrogen (N) fertilisation may affect the use of precipitation in terms of vegetative and flowering response of 15-year-old carob trees during a 3-year experiment. A field trial was conducted in 1997, 1998 and 1999 in Algarve (Southern Portugal) in a calcareous soil. Four fertilisation treatments were tested: no fertiliser (control); 0.8 kg N/tree (N treatment); 1 kg K 2 O/tree (K treatment) and 0.8 kg N/tree plus 1 kg K 2 O/tree (NK treatment). No irrigation was applied during the experimental period. Branch length increments were measured every month throughout the growing season and inflorescence number was registered once per year. There was a strong seasonal effect on vegetative growth, since low levels of precipitation (115 mm) during October 1998–March 1999 suppressed the increment in branch length. N supplied to the trees (N and NK treatments) tended to increase water use indices in terms of vegetative growth. No response to K alone was observed in trees fertilised only with K. The number of inflorescences increased throughout the experimental period, particularly for N and NK treatments, and a reduction of the precipitation amount during April, May and June, may also enhance flowering. This knowledge could be important when making decisions concerning fertilisation under dry conditions. The results reported here indicate that tree growth (expressed as the branch growth) and flower production under dry-farming conditions, may be achieved by applying 0.8 kg of N (as ammonium nitrate) per tree during the growing season. However, N uptake and use depends on soil water availability.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Dissertação de mest., Ciências Biomédicas, Departamento de Ciências Biomédicas e Medicina, Univ. do Algarve, 2011

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Previous work on Betula spp. (birch) in the UK and at five sites in Europe has shown that pollen seasons for this taxon have tended to become earlier by about 5–10 days per decade in most regions investigated over the last 30 years. This pattern has been linked to the trend to warmer winters and springs in recent years. However, little work has been done to investigate the changes in the pollen seasons for the early flowering trees. Several of these, such as Alnus spp. and Corylus spp., have allergens, which cross-react with those of Betula spp., and so have a priming effect on allergic people. This paper investigates pollen seasons for Alnus spp. and Corylus spp. for the years 1996–2005 at Worcester, in the West Midlands, United Kingdom. Pollen data for daily average counts were collected using a Burkard volumetric trap sited on the exposed roof of a three-storey building. The climate is western maritime. Meteorological data for daily temperatures (maximum and minimum) and rainfall were obtained from the local monitoring sites. The local area up to approximately 10 km surrounding the site is mostly level terrain with some undulating hills and valleys. The local vegetation is mixed farmland and deciduous woodland. The pollen seasons for the two taxa investigated are typically late December or early January to late March. Various ways of defining the start and end of the pollen seasons were considered for these taxa, but the most useful was the 1% method whereby the season is deemed to have started when 1% of the total catch is achieved and to have ended when 99% is reached. The cumulative catches (in grains/m3) for Alnus spp. varied from 698 (2001) to 3,467 (2004). For Corylus spp., they varied from 65 (2001) to 4,933 (2004). The start dates for Alnus spp. showed 39 days difference in the 10 years (earliest 2000 day 21, latest 1996 day 60). The end dates differed by 26 days and the length of season differed by 15 days. The last 4 years in the set had notably higher cumulative counts than the first 2, but there was no trend towards earlier starts. For Corylus spp. start days also differed by 39 days (earliest 1999 day 5, latest 1996 day 44). The end date differed by 35 days and length of season by 26 days. Cumulative counts and lengths of season showed a distinct pattern of alternative high (long) and low (short) years. There is some evidence of a synchronous pattern for Alnus spp.. These patterns show some significant correlations with temperature and rainfall through the autumn, winter and early spring, and some relationships with growth degree 4s and chill units, but the series is too short to discern trends. The analysis has provided insight to the variation in the seasons for these early flowering trees and will form a basis for future work on building predictive models for these taxa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Birch pollen is highly allergenic. Knowledge of daily variations, atmospheric transport and source areas of birch pollen is important for exposure studies and for warnings to the public, especially for large cities such as London. Our results show that broad-leaved forests with high birch tree densities are located to the south and west of London. Bi-hourly Betula pollen concentrations for all the days included in the study, and for all available days with high birch pollen counts (daily average birch pollen counts >80 grains/m3), show that, on average, there is a peak between 1400 hours and 1600 hours. Back-trajectory analysis showed that, on days with high birch pollen counts (n=60), 80% of air masses arriving at the time of peak diurnal birch pollen count approached North London from the south in a 180 degree arc from due east to due west. Detailed investigations of three Betula pollen episodes, with distinctly different diurnal patterns compared to the mean daily cycle, were used to illustrate how night-time maxima (2200–0400 hours) in Betula pollen counts could be the result of transport from distant sources or long transport times caused by slow moving air masses. We conclude that the Betula pollen recorded in North London could originate from sources found to the west and south of the city and not just trees within London itself. Possible sources outside the city include Continental Europe and the Betula trees within the broad-leaved forests of Southern England.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The mesoscale (100–102 m) of river habitats has been identified as the scale that simultaneously offers insights into ecological structure and falls within the practical bounds of river management. Mesoscale habitat (mesohabitat) classifications for relatively large rivers, however, are underdeveloped compared with those produced for smaller streams. Approaches to habitat modelling have traditionally focused on individual species or proceeded on a species-by-species basis. This is particularly problematic in larger rivers where the effects of biological interactions are more complex and intense. Community-level approaches can rapidly model many species simultaneously, thereby integrating the effects of biological interactions while providing information on the relative importance of environmental variables in structuring the community. One such community-level approach, multivariate regression trees, was applied in order to determine the relative influences of abiotic factors on fish assemblages within shoreline mesohabitats of San Pedro River, Chile, and to define reference communities prior to the planned construction of a hydroelectric power plant. Flow depth, bank materials and the availability of riparian and instream cover, including woody debris, were the main variables driving differences between the assemblages. Species strongly indicative of distinctive mesohabitat types included the endemic Galaxias platei. Among other outcomes, the results provide information on the impact of non-native salmonids on river-dwelling Galaxias platei, suggesting a degree of habitat segregation between these taxa based on flow depth. The results support the use of the mesohabitat concept in large, relatively pristine river systems, and they represent a basis for assessing the impact of any future hydroelectric power plant construction and operation. By combing community classifications with simple sets of environmental rules, the multivariate regression trees produced can be used to predict the community structure of any mesohabitat along the reach.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Tese de doutoramento, Biologia (Biologia Celular), Universidade de Lisboa, Faculdade de Ciências, 2016