Loading...
4 results
Search Results
Now showing 1 - 4 of 4
- In vitro cloning of Ficus carica L. adult treesPublication . Nobre, J.; Romano, AnabelaThe present work reports in vitro studies carried out with two Portuguese cultivars of fig-tree: Berbera (a dried fig) and Lampa (a fresh fig). Procedures were developed to overcome difficulties associated with the establishment of adult material due to contaminants and exudation of phenolic compounds. An improved growth and development of the apical shoot-tips was obtained on Muriithi medium supplemented with 0.05 % PVP. The highest multiplication rate, 5.3 shoots per culture, every three weeks, was achieved on a similar basal medium supplemented with 2.2 mu M BA and devoid of NAA. The best rooting response (96.9 %) was observed on the medium containing 2.5 mu M IBA. Plantlets were successfully acclimatized and grown for three months in the greenhouse, and then field established for orchard production. Micropropagated plants produced fruits two years after field-establishment. These results are a promising step in the direction of in vitro cloning of valuable genotypes directly from field-grown plants and the conservation of plant genetic resources.
- Influence of growth-regulators on shoot proliferation in Quercus-Suber LPublication . Romano, Anabela; Noronha, C.; Martins-Loução, M. A.Procedures have been developed to standardize the multiplication stage during mature cork-oak (Quercus suber L.) micropropagation. Axillary and terminal buds were established on Gresshoff and Doy basal medium containing 1 mg I−1 of 6-benzylaminopurine (BAP). Initiation of cultures was possible all over the year. The effects of BAP, Z, IBA, 1AA and NAA and various nutrient formulae on shoot growth and proliferation was investigated. BAP was more suitable than zeatin. Shoot proliferation and elongation were strongly improved by the combination BAP/IAA in the presence of low salt media, like Gresshoff and Doy or Woody Plant medium. Both rates were significantly increased when a double-phase culture system was used. Shoots have been multiplied for 1 year at the rate of three to four-fold every 4 weeks without any decline of vigour. Rooting was achieved by briefly dipping the basal ends of in vitro regenerated shoots in an IBA concentrated solution. The results here reported constitute a promising step towards large scale in vitro propagation of a species in which conventional vegetative propagation by cuttings is very difficult.
- In vitro cold storage of cork oak shoot culturesPublication . Romano, Anabela; Martins-Loução, M. A.A simple system for in vitro conservation of cork oak shoot cultures (Quercus suber L.) is described. Cultures were stored in vitro on multiplication medium at 5 +/- 1 degrees C without an intervening subculture for two years. The viability, multiplication rate and shoot elongation were evaluated after storage under dark and light conditions. Culture viability was negatively affected by light. In contrast, 50% of cultures survived after two years of cold storage in the dark. Multiplication rate of dark-stored cultures was similar to the controls, and shoot elongation was significantly higher. Although the assessment of multiplication rate/shoot elongation is done at the end of the first multiplication cycle, we observed that at least in some species such as Quercus suber, it is advisable to study the responsiveness of cultures during the first three multiplication cycles following storage. The rooting capacity of shoots produced from dark-stored cultures was similar to non-stored controls. Cultures stored for 6, 12 or 24 months without subculture have similar responsiveness as the ones subcultured monthly. The storage of cultures at 5 degrees C in the dark appears to be a promising technique for medium-term conservation of cork oak germplasm.
- Role of carbohydrates in micropropagation of cork oakPublication . Romano, Anabela; Noronha, C.; Martins-Loução, M. A.The influences of carbon sources, fructose, glucose, sorbitol and sucrose on shoot proliferation and in vitro rooting of cork oak (Quercus suber L.) were compared at a wide range of concentrations (1-6%, w/v). The highest number of shoots occurred on glucose-containing medium. Nevertheless, we have chosen 3% sucrose which induced a similar rate of proliferation but favoured shoot elongation, permitting an effectively higher number of shoots during transfers. Sorbitol and autoclaved fructose did not stimulate shoot proliferation. Adventitious root formation was strongly dependent on carbohydrate supply. Sorbitol and autoclaved fructose were completely ineffectively on rooting induction. Glucose was the most effective carbon source on rooting promotion followed by sucrose and filter-sterilized fructose. The rooting response induced by fructose was dependent on the sterilizing procedure. The number of adventitious roots produced per shoot increased with increasing glucose and sucrose concentration. The content of reducing sugars in leaves of proliferation cultures and in leaves and roots of rooted plantlets was more dependent on carbon concentration than on glucose or sucrose supplement. The results presented here show that carbohydrate requirements during cork oak micropropagation depend upon the phase of culture. Sucrose (3%) and glucose (4%) were the best carbon sources respectively during proliferation and rooting phases.