Influência da benzilaminopurina e da cinetina na micropropagação de plantas jovens de Lavandula luisieri (Rozeira) Rivas-Martínez

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

Avaliação de parâmetros fotossintéticos em microplantas de Castanheiro durante a fase de aclimatização.

O objetivo deste trabalho foi realizar um estudo comparativo em microplantas de castanheiro com dois sistemas de expressão e desenvolvimento radicular, in vitro e ex vitro, e com duas intensidades luminosas (150 e 250 μmol m-2 s-1) durante a aclimatização, e a sua influência no desenvolvimento das microplantas durante esta fase, através da quantificação de parâmetros fotossintéticos. A concentração de clorofilas, após os tratamentos de aclimatização, dependeu quer do tipo de sistema radicular que as plantas possuíam no início da aclimatização, quer do regime luminoso a que as plantas estiveram submetidas. As plantas com enraizamento in vitro e aclimatizadas sob menor irradiância foram as que apresentaram valores superiores para a clorofila total (7,74 mg g-1ps), mas com o valor mais baixo na razão entre clorofila a/b (2,7). Quando comparamos os valores registados para os parâmetros fotossintéticos das plantas dos diferentes tratamentos, verificamos que as taxas de fotossíntese aparente vão gradualmente aumentando à medida que as novas folhas se vão desenvolvendo (0,75 μmol CO2 m-2 s-1 nas folhas persistentes e 3,43 μmol CO2 m-2 s-1 na folha 3 das plantas aclimatizadas a 250 μmol m-2 s-1). O mesmo acontece na capacidade fotossintética (3,93 μmol O2 m-2 s-1 nas folhas persistentes e 7,87 μmol O2 m-2 s-1 na folha 3 das plantas aclimatizadas a 250 μmol m-2 s-1). Estes valores foram tendencialmente superiores nas plantas com enraizamento ex vitro e aclimatizadas a maior irradiância, pelo que a um melhor sistema radicular e uma maior disponibilidade luminosa correspondeu um acréscimo na competência fotossintética, o que resultou num melhor desenvolvimento morfofisiológico das plantas.Abstract The aim of this study was to conduct a comparative study in chestnut microplants with two systems of expression and root development, in vitro and ex vitro, and with two light intensities (150 and 250 μmol m-2 s-1) during acclimatization, and its influence on the development of microplants during this phase, through the quantification of photosynthetic parameters. The chlorophyll concentration after acclimatization treatments depended on both type of root system that the plants had at the beginning of acclimatization, whether the light intensity to which the plants were subjected. Plants with roots in vitro and acclimatized under lower irradiance showed the higher values for total chlorophyll (7.74 mg g-1ps), but with the lowest value of the ratio of chlorophyll a/b (2.7). When the values recorded for the photosynthetic parameters of plants of different treatments were compared, we found that the rates of apparent photosynthesis gradually increasing as the new leaves are developed (0.75 μmol CO2 m-2 s-1 in persistent leaves and 3.43 μmol CO2 m-2 s-1 on leaf 3 on plants acclimatized to 250 μmol m-2 s-1). The same happens in photosynthetic capacity (3.93 μmol O2 m-2 s-1 in persistent leaves and 7.87 μmol O2 m-2 s-1 on leaf 3 of plants acclimatized to 250 μmol m-2 s-1). These values were higher in plants with ex vitro rooting and acclimatization to higher irradiance, so a better root system availability and a higher light availability, corresponding to an increase in the photosynthetic ability, resulting in a better morphophysiological plant development.info:eu-repo/semantics/publishedVersio

Growth analysis of in vitro-regenerated chestnuts during the acclimatization stage using elevated CO2

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

Effects of elevated CO2 on acclimatization of in-vitro regenerated chestnuts

Comunicação oral apresentada no II International Symposium on Acclimatization and Establishment of Micropropagated Plants que decorreu em 2004 em Cancún, no México.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 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). The plants under elevated CO2 showed an 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 problem during this critical phase of the autotrophic competence acquiring process. The net photosynthesis rate 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. We think that the gains that we have achieved with the use of elevated CO2 can be more significant if an higher light intensity can be used instead because they have a better response capacity to an increment of the level of irradiance

Efeito dos polinizadores himenópteros em pomar de cereja

Efeito dos polinizadores himenópteros em pomar de cereja

Laboratório de Biologia.

Laboratório de Biologia.info:eu-repo/semantics/publishedVersio

Atividade antioxidante e antimicrobiana de extratos de plantas de Pterospartum tridentatum (L.) Willk. in vitro e silvestres

Atividade antioxidante e antimicrobiana de extratos de plantas de Pterospartum tridentatum (L.) Willk. in vitro e silvestres.info:eu-repo/semantics/publishedVersio

Adventitious rooting in microshoots of chestnut hybrid (Castanea sativa x C. crenata) in the presence of indole-3-butyric acid: The role of changes in endogenous indole-3-acetic acid, indole-3-acetylaspartic acid and indole-3- butyric acid levels

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

Identificação de compostos bioativos em plantas silvestres e plantas in vitro de Pterospartum tridentatum (L.) Willk.

Identificação de compostos bioativos em plantas silvestres e plantas in vitro de Pterospartum tridentatum (L.) Willk.info:eu-repo/semantics/publishedVersio

Drip vs. surface irrigation: a comparison focussing on water saving and economic returns using multicriteria analysis applied to cotton

Research PaperThis study explores the use of drip and surface irrigation decision support systems to select among furrow, border and drip irrigation systems for cotton, considering water saving and economic priorities. Data refers to farm field observations in Northeast of Syria. Simulation of drip irrigation was performed with MIRRIG model for various alternatives: double and single row per lateral, emitter spacing of 0.5 and 0.7 m, six alternative pipe layouts and five self-compensating and non-compensating emitters. Furrow and border irrigation alternatives were designed and ranked with the SADREG model, considering lasered and nonlasered land levelling, field lengths of 50e200 m and various inflow discharges. A multicriteria analysis approach was used to analyse and compare the alternatives based upon economic and water saving criteria. Results for surface irrigation indicate a slight advantage for long non-lasered graded furrows; non-lasered alternatives were selected due to economic considerations. For drip irrigation, the best ranking is for systems having lower costs, mainly with double rows per lateral and larger emitter spacing. Comparing surface and drip irrigation systems, despite low cost, drip alternatives may lead to 28e35% water saving relative to improved graded furrows, and increase water productivity from 0.43 kg m 3 to 0.61 kg m 3, surface irrigation provides higher farm returns. Drip irrigation is selected only when high priority is assigned to water saving. Deficit irrigation does not change this pattern of results. Apparently, adopting drip irrigation requires appropriate economic incentives to farmers, changes in the structure of production costs and increased value of productioninfo:eu-repo/semantics/publishedVersio