Browsing by Author "Oliveira, G."
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- Desenvolvimento linguístico na perturbação do espectro do autismo - eye tracking enquanto metodologia de avaliação da perceção da falaPublication . Bandeira de Lima, Cláudia; Severino, Cátia; Butler, Joseph; Oliveira, G.; Vigário, Marina
- Effects of bark-stripping on the water relations of Quercus suber LPublication . Correia, O. A.; Oliveira, G.; Martins-Loução, M. A.; Catarino, F. M.Quercus suber, font primària de la undústria del suro, es posa en producció cada 9-10 anys. L’ objectiu principal d’aquest treball és investigar la influència de la lleva o pela del suro sobre l’ activitat estomàtica i les relations hídriques de la surera. Amb aquest propòsit s’han mesurat els canvis diurns de transpiración, la conductància estomàtica i el potencial hídric, en fase prévia i posterior a la pela, durante el mesos de Juliol i Agost dels anys 1989 i 1990. La pela es va efectuar amb diferents intensitas. Les pèrdures d’aigua de la superfície pelada també van ser objecte de mesura. Els resultats mostren que les pelades severes poden determinar una disminució de la conductància estomàtica i considerables pèrdues d’ aigua. L’ <> determinat per l’extracció del suro no guarda relació clara amb el coeficient de pela sinó amb l’aigua perduda pel tronc, que varia d’arbre en arbre probablement segons la composició dels teixits del floema. Quercus suber is the primary source of industrial cork and can produce cork every 9-10 years. The main objective of this work was to investigate the influence of bark stripping on the stomatal activity and water relations of cork-oak. For this purpose, diurnal changes on transpiration, stomatal conductance and water potencial were measured before and after bark stripping during July and August 1989 and 1990. The stripping on the trees had been done at various intensities. The water loss by the stripped surface was also measured. These results show that severe bark-stripping may lead to a decrease in stomatal conductance and considerable water losses. The stripping stress is not clearly dependent on the stripping coefficients, but rather on the water lost by the trunk which varies from tree to tree probably according to the phloemic tissues composition.
- Growth patterns of cork-oak (Quercus suber L.) under natural conditionsPublication . Oliveira, G.; Correia, O. A.; Martins-Loução, M. A.; Catarino, F. M.
- Water relations of cork-oak (Quercus suber L.) under natural conditionsPublication . Oliveira, G.; Correia, O. A; Martins-Loução, M. A.; Catarino, F. M.Daily and annual courses of leaf transpiration, stomatal conductance and shoot water potential of four Quercus suber individuals were compared in a semi-natural stand in southwest Portugal, from spring 1989 to early summer 1990. The trees investigated showed annual patterns typical of evergreen sclerophyllous species but varied in their range of stomatal operation. This appeared to be related to differences in hydraulic conductivity in the root-to-leaf pathway. Maximum stomatal conductance and transpiration rates occurred from March to June. Water stress was found to be moderate and winter cold stress due to low air and soil temperatures appeared to have an influence on plant water balance through their effects on flow resistances. Abbreviations." gsw stomatal conductance; gmax maximum stomatal conductance, PAR, photosynthetically active radiation; RH, relative humidity of the air; T, leaf transpiration; Ta, air temperature; TL, leaf temperature; Tmax maximum leaf transpiration; ∆W, air-to-leaf vapor pressure difference; W, shoot water potential; ψPD, predawn shoot water potential; ψMIN, minimum shoot water potential.