Type

Database

Creator

Date

Thumbnail

Search results

18 records were found.

A utilização de técnicas in vitro para o armazenamento e conservação de germoplasma, apresenta-se hoje como uma alternativa de valor potencial aos tradicionais métodos de conservação. De facto, a possibilidade de manter partes vegetativas de plantas em condições limitadas de espaço e manutenção por longos períodos de tempo, tornam essas técnicas suficientemente atractivas para constituírem no futuro uma garantia da manutenção de recursos genéticos escassos e limitados. Neste estudo referem-se os resultados obtidos na conservação pelo frio de rebentos axilares de cerejeira com 1 ± 0.2 com de comprimento, obtidos a partir de culturas com 1 ano de idade e mantidos a 4ºC em meio de MS com diferentes concentrações de sacarose e de reguladores de crescimento, quer na sobrevivência, quer nas taxas de proliferação, durante três subcultivos suc...
Os significativos avanços que têm sofrido as técnicas de propagação clonal, muitas vezes impulsionadas por necessidades de mutliplicar rapidamente plantas obtidas por melhoramento genético, têm vindo a permitir aplicá-las com êxito a um cada vez maior número de espécies. As razões e as vantagens da multiplicação vegetativa são conhecidas de todos, das quais podemos destacar a manutenção dos clones seleccionados quer pelas suas características produtivas, quer por resistência a doenças, a possibilidade de propagar plantas que não produzem sementes viáveis e ainda pelo facto de permitirem reduzir os períodos de juvenilidade.
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 sus...
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 acqui...
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.
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 ...
In the present study, aerial parts of Pterospartum tridentatum plants, collected in three locations in Portugal, at different vegetative stages, were evaluated for their total phenolic content and the antioxidant activity of aqueous extracts. The influence of the seasonal variation in the yield and composition of the extracts was evaluated, in order to select the most appropriate harvest season. Among the populations assayed, the extraction yields have some differences with the harvest period but the highest yield extraction was obtained in the flowering season, using flowers (19.4g/100g plant dry mass) and the lowest extraction yield was also obtained in the same period but using stems. The antioxidant activity of the solid extracts of Pterospartum tridentatum aerial parts, was determined by the radical scavenging activity method usin...
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 Malc...
Want to know more?If you want to know more about this cutting edge product, or schedule a demonstration on your own organisation, please feel free to contact us or read the available documentation at http://www.keep.pt/produtos/retrievo/?lang=en