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O sumário pormenorizado da lição que agora se apresenta, insere-se na disciplina de Biologia Celular, disciplina do 1° ano, lº semestre, da estrutura curricular dos cursos de Licenciatura em Ciências Agrárias, Ramo Agrícola e Ramo Animal, de Engenharia Florestal e de Engenharia do Ordenamento e Recursos Naturais, cujo programa se encontra em anexo. Trata-se de uma disciplina de carácter geral onde são ministrados aos alunos princípios e conceitos básicos sobre a diversidade do mundo vivo, constituintes, organização e funcionamento celular, tendo em vista a compreensão de uma forma integrada das inter-relações entre seres e do funcionamento celular enquanto unidade estrutural da sua constituição. O ponto do programa que agora nos propomos abordar, “Cultura de tecidos vegetais: princípios e aplicações”, surge com intenção de proporcionar aos alunos alguns aspectos de aplicação dos conhecimentos já obtidos permitindo-lhes a percepção da importância dos mecanismos per si no funcionamento e nas respostas dos seres vivos de acordo com todos os factores que sobre eles exercem influência. Em concreto, é intenção deste ponto permitir aos alunos uma primeira abordagem de modelos de desenvolvimento vegetal e de que forma eles podem ser utilizados não só para a sua própria compreensão mas, também, alertar os alunos para potenciais aplicações destas metodologias que são hoje meios indispensáveis noutras áreas do saber. Este aspecto permitirá estabelecer uma ligação com futuras disciplinas curriculares, como sejam a Genética, a Fisiologia e Nutrição Vegetal, a Ecofisiologia, as Técnicas de Melhoramento Florestal, o Melhoramento Vegetal e as Tecnologias de Multiplicação de Plantas, de acordo com os respectivos cursos, e onde estes temas serão retomados e desenvolvidos tendo em vista as suas especificidades. Trata-se, contudo, da apresentação de assuntos em que os alunos poderão deparar com algumas dificuldades de compreensão, uma vez que temos consciência que para o seu global entendimento e percepção das suas potenciais implicações, tornava-se necessário que os alunos já tivessem conhecimentos que apenas irão ser adquiridos posteriormente, em especial nas disciplinas atrás referidas. No entanto julgamos que esta é uma questão de dialéctica, inerente ao próprio sistema de ensino/aprendizagem, isto é, a interdependência e a interligação entre matérias ao longo de uma formação global de um curso superior. Como última referência uma breve explicação. O conteúdo deste ponto que irá ser apresentado durante sessenta minutos, em situação real de ensino está programado para duas a três horas, uma vez que consideramos de grande importância a participação e intervenção dos alunos, quer por iniciativa própria, quer por iniciativa do docente, numa tentativa de os manter sempre que possível com uma atitude activa e não de meros espectadores. Além disso permitirá ao docente ir resolvendo alguns pequenos problemas de compreensão a que atrás fizemos referência.
Comunicação apresentada no Simpósio de Propagação Vegetativa de Espécies Lenhosas que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 18 a 20 de Outubro de 1996.
O evento foi organizado pelo Centro de Estudos de Desenvolvimento Regional (CEDER) do Instituto Politécnico de Castelo Branco.
The aim of this study was to compare two rooting environmental conditions for root development, in vitro and ex vitro, and their influence in anatomical differentiation.
Comunicação apresentada no Simpósio de Propagação Vegetativa de Plantas Lenhosas que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 18 a 20 de Outubro de 1996.
A realização desta Jornada Técnica sobre o Castanheiro, inseriu-se no âmbito da divulgação do Potojecto PAMAF 6127.
Great advances have been made but some cultured plantlets still having a poor performance during the ex vitro stages and more specifically during the acclimatization and the nursery establishment stages. The problem is highly complex and requires the fast adaptation of plants growing in artificial conditions when transferred to the natural conditions. Until now, there is no consensus on the better strategy to obtain a higher efficiency of the propagation protocols while optimising acclimatization success. In this study we present the results of growth analysis of in vitro-regenerated chestnut hybrid plantlets (Castanea sativa x C. crenata), during the acclimatization stage, using two CO2 concentrations (350 µLL-1 and 700 µLL-1) at 250 µmol m- 2 s-1 as irradiance level (PPFD). Elevated CO2 did not affect the survival rate and it was susceptible to increase progressive autotrophy, expressed by a significant increase in relative growth, shoot/root ratio and leaf area ratio (LAR). For both CO2 concentrations, the plants are successfully acclimatized and they are in good conditions to be transferred to a greenhouse to continue their development for the rest of the season, and in the next winter/spring they can go to the field. The plants under elevated CO2 showed a higher stomatal frequency but the new leaves developed at the end of acclimatization revealed a gradual normal stomatal morphology and they reduced the stomatal frequency. Their morphology showed an effective water loss control, which is one of the most important problems during this critical phase of the autotrophic competence acquiring process. The net photosynthesis rate (A) was similar in both treatments but the plants acclimatized at elevated CO2 showed an increase in maximum photosynthetic rate (Amax), and this can lead to a better physiological development. The different analysed leaf types showed a marked increment of the maximum photosynthetic rate as the new leaves developed during the acclimatization stage. Net photosynthesis rate and the maximum photosynthetic rate are light dependent, and are positively affected by the highest irradiance level. We think that the gains that we have achieved with the use of elevated CO2 can be more significant if a higher light intensity can be used instead because they have a better response capacity to an increment of the level of irradiance.
Com o objectivo de desenvolver metodologias de micropropagação de Lavandula luisieri, foram realizados um conjunto de ensaios tendo como material vegetal explantes provenientes de germinação de sementes in vitro. Os ensaios de multiplicação estabelecidos com explantes secundários provenientes das plantas in vitro da população stock mostraram que a 6- benzilaminopurina se mostrou mais eficaz, comparativamente com a cinetina, na promoção e desenvolvimento dos rebentos tendo na concentração de 0.44 µM sido obtidos uma média de 2.2 rebentos com taxa de multiplicação de 3 e comprimentos de 20.9 mm. Contudo a utilização de concentrações mais elevadas de 6-benzilaminopurina são susceptíveis de promoverem elevadas taxa de vitrificação (35%) com consequente perda das culturas. Durante esta fase de multiplicação registou-se a formação de raízes nos rebentos tendo as percentagens de enraizamento sido maiores nos meios com cinetina, 57.5% com 0.46 µM, e no controlo. A aclimatização destas plantas foi feita com 100% de sobrevivência o que indicia o bom estado fisiológico das plantas regeneradas in vitro.
Comunicação oral apresentada no II International Symposium on Acclimatization and Establishment of Micropropagated Plants que decorreu em 2004 em Cancún, no México.
The aim of the present study was to evaluate the total phenolic content and antioxidant activity of aqueous extracts of Pterospartum tridentatum samples, collected in three locations in Portugal, at diferente vegetative stages.
Comunicação apresentada no Simpósio Propagação Vegetativa de Espécies Lenhosas que decorreu de 18 a 20 de Abril de 1996, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco.
Endogenous levels of IAA, IAAsp and IBA were quantified during the first 8 days of in vitro rooting of the chestnut hybrid, clone M3 by high performance liquid chromatography. Rooting was induced either by dipping the basal ends of the shoots into 1 gl-1 IBA solution for 1 minute or by subculturing the shoots on agar rooting medium with 3 mgl-1 IBA for 5 days. For root development the induced shoots were transferred to auxin-free agar medium. Auxins were measured in the apical and basal parts of the shoots by means of high performance liquid chromatography. Endogenous levels of IAA and IAAsp were higher in IBA-treated shoots than in control shoots. In extracts of the basal parts of the shoots, the concentration of free IAA showed a transient peak at day 2, in both root inductive methods, a subsequent gradual decrease for the remainder of the time course was observed. The concentration of IAAsp peaked at day 6 in extracts of the basal parts of shoots induced with 3 mgl-1 IBA for 5 days, whereas shoots induced by dipping showed an initial increase until day 2, and then remained stable. In extracts from basal shoot portions induced by dipping and by IBA in the medium, IBA concentration showed a transient peak at 24 h and 48 h, respectively, remaining stable after day 4 for the dipping method, whilst showing a significant drop between day 4 and 6 for the other induction treatment. All quantified auxins remained at a relatively low level, virtually constant, in extracts from apical shoot portions, as well as in extracts from control of non-rooting shoots.
The aerial parts of Pterospartum tridentatum, a wild growing species in Portugal used in traditional medicine and gastronomy, were harvested at different stages (vegetative phase, flowering phase and beginning of dormancy) in two locations in Portugal (Malcata and Gardunha mountains), and the respective aqueous extracts have been studied. The influence of the seasonal variation in the extraction yield, total phenolic content and antioxidant activity was evaluated. The extraction was carried out in boiling water in consecutive steps. After each step, the aqueous extract was separated and fresh water was added maintaining the same plant material. The procedure was repeated seven times, within an overall time period of 180 minutes. Higher extraction yields were achieved with plant stems collected at the vegetative phases, either from Malcata or Gardunha regions. The total phenolic content of the extracts from Malcata plants ranged from 273 mg to 400 mg gallic acid equivalent/g dry matter, which was quite similar to that determined for extracts from Gardunha (245 to 394 mg gallic acid equivalent/g dry matter). The antioxidant activity was determined by the radical scavenging activity method using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH). The greatest radical scavenging activity was observed in the flowers extracts, even though all extracts produced presented a good antioxidant activity. Furthermore, the antioxidant activity was not affected by the exposure of the plant material at 100ºC for long periods of time (180 min). The results show that Pterospartum tridentatum has a great potential to be used as a new source of natural antioxidants for the food industry.
Tendo em vista a valorização deste recurso natural, este trabalho tem como principal objectivo a produção de extractos aquosos das partes aéreas da carqueja e a sua caracterização.
The morphology and physiology of plants grown in vitro are regulated by various environmental factors such as light, temperature, humidity and carbon dioxide. Light, in its various parameters such as spectral quality, photon flux and photoperiod, is an important factor among these and generally influences the overall growth and development of plants in vitro. Light sources commonly used for in vitro plant culture are fluorescent lamps, although some research and commercial laboratories also use sodium metal or incandescent metal halide lamps. The spectral of those lamps range from 350 to 750 nm and contain blend lights that differentially affect in vitro plant growth. Recently, light emitting diodes (LEDs) have been developed and are nowadays used as an alternative source of fluorescent light for the development of plants both in greenhouses and in vitro culture rooms. In order to test the influence of these two types of light during multiplication phase, a multiplicity experiment was carried out using two species: a chestnut hybrid (Castanea sativa x C. crenata), clone M2 and the prickled broom (Pterospartum tridentatum (L.) Willk.), Malcata ecotype. Two types of light were tested, "cool white" fluorescent light and LED light with blue and red colors. It was found that LED illumination exerted a significant positive effect on the differentiation of shoots in the case of prickled broom (5.6 instead of 4.9 split shoots under fluorescent light). In the parameters of shoot length, we found that this type of lighting favored the elongation in both species. Regarding the parameters of fresh and dry weight, LED lighting caused a greater effect on the chestnut than on prickled broom. Some physiological parameters (chlorophylls, carotenoids and proteins) were also analyzed and showed to be influenced by the type of light during the development of microplants.
The morphology and physiology of plants grown in vitro are regulated by various environmental factors such as light, temperature, humidity and carbon dioxide. Light, in its various parameters such as spectral quality, photon flux and photoperiod, is an important factor among these and generally influences the overall growth and development of plants in vitro. Light sources commonly used for in vitro plant culture are fluorescent lamps, although some research and commercial laboratories also use sodium metal or incandescent metal halide lamps. The spectral of those lamps range from 350 to 750 nm and contain blend lights that differentially affect in vitro plant growth. Recently, light emitting diodes (LEDs) have been developed and are nowadays used as an alternative source of fluorescent light for the development of plants both in greenhouses and in vitro culture rooms. In order to test the influence of these two types of light during multiplication phase, a multiplicity experiment was carried out using two species: a chestnut hybrid (Castanea sativa x C. crenata), clone M2 and the prickled broom (Pterospartum tridentatum (L.) Willk.), Malcata ecotype. Two types of light were tested, "cool white" fluorescent light and LED light with blue and red colors. It was found that LED illumination exerted a significant positive effect on the differentiation of shoots in the case of prickled broom (5.6 instead of 4.9 split shoots under fluorescent light). In the parameters of shoot length, we found that this type of lighting favored the elongation in both species. Regarding the parameters of fresh and dry weight, LED lighting caused a greater effect on the chestnut than on prickled broom. Some physiological parameters (chlorophylls, carotenoids and proteins) were also analyzed and showed to be influenced by the type of light during the development of microplants.