Browsing by Author "Rodrigues, P."
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- Coeficientes culturais da casta Touriga Nacional na região do DãoPublication . Rodrigues, P.; Pedroso, V.; Gouveia, J.P.; Martins, S.; Lopes, C.M.; Alves, I.Com o objectivo de estudar o efeito da rega e do regime hídrico no comportamento da casta Touriga Nacional foi instalado um ensaio de rega numa vinha do Centro de Estudos Vitivinícolas do Dão, em Nelas. A transpiração da sebe de vinha foi estimada a partir dos registos de temperatura radiativa da sua superfície, recorrendo a um modelo bi-camada que tem por base o princípio da partição do balanço energético entre os componentes do coberto vegetal (videiras, solo e subcoberto herbáceo) admitindo que, do ponto de vista energético, a sebe e o substrato (solo+subcoberto) actuam separadamente e em paralelo. Os fluxos de calor latente da sebe de videiras são determinados a partir dos fluxos de calor sensível e do balanço de radiação. A evolução temporal de Ec/ETo na modalidade de rega plena (FI) permite identificar três fases e corresponde à forma geral da curva de Kcb indicada para a generalidade das culturas. A relação entre o coeficiente de secura (Ks) e fracção de água utilizável do solo até 130 cm de profundidade (FTSW130) é bifásica. Para valores de FTSW130 superiores a 40-50%, o Ks é aproximadamente constante, registando valores em torno de 1, correspondente a condições de conforto hídrico. Com valores de FTSW130 inferiores, o Ks tende a decrescer à medida que a reserva de água no solo diminui. Os menores valores de Ks foram registados nos anos de 2005 (Ks = 0,48) e 2006 (Ks = 0,55), ambos na modalidade não regada (NI).
- Daily evolution of the balance of radiation components in a vineyard canopy at the Dão wine region, PortugalPublication . Rodrigues, P.; Pedroso, V.; Gouveia, J.; Martins, S.; Lopes, C.M.; Alves, I.In order to validate a model of vine transpiration based on radiative surface temperature a field trial was conducted in a vineyard in the Do region, centre of Portugal, with the cultivar "Touriga Nacional". The model is based on the partition of net radiation between the components of the canopy (vines, soil, and grass cover), considering that the vines and the undercover (sou plus grass cover) act separately and in parallel. Thus, the latent heat flux from the vines to the amosphere (XT) is determined from vine net radiation (Rn) and sensible heat flux (H). The partition of net radiation (Rn) between the undercover (Rn) and the vines (Rn) is made considering the exponential form for radiation extinction, with the coefficient of extinction being corrected with a factor dependent on the zenital solar angle (p) while leaf area index (LAI) is corrected with a clumping factor, Q(p). Sensible heat flux from the vines (H) is calculated from radiative temperature (Te) considering that the fluxes from the different origins are independent and that there are two resistances in series between the canopy and the atmosphere: the leaf boundary layer resistance (raHc) and the aerodynamic resistance of the crop (raH). Besides the estimation of the daily values of transpiration, the model allows to study the evolution of the different components of the radiation balance throughout the day. The daily evolution of the evaporation fraction from the vines (FE) can be approximated by a concave curve. Values of FE > 1 show that, under certain circumstances and periods of the day, energy used for transpiration (XT) is greater than crop net radiation, which indicates that there are exchanges of energy between the several components of the surface, namely when evaporative demand from the atmosphere is high and there are no soil water restrictions. The model also shows that, regardless ofthe soil water status, transpiration is a big part ofRn when these values are low (in the beginning ofthe morning and late afternoon).
- Daily evolution of the components of the balance of radiation of vines in a vineyard in the Dão regionPublication . Rodrigues, P.; Pedroso, V.; Gouveia, J.P.; Martins, S.; Lopes, C.M.; Alves, I.In order to validate a model of vine transpiration based on radiative surface temperature a field trial was conducted in a vineyard in the Dão region, centre of Portugal, with the cultivar “Touriga Nacional”. The model is based on the partition of net radiation between the components of the canopy (vines, soil, and grass cover), considering that the vines and the undercover (soil plus grass cover) act separately and in parallel. Thus, the latent heat flux from the vines to the atmosphere (lTc) is determined from vine net radiation (Rnc) and sensible heat flux (Hc). The partition of net radiation (Rn) between the undercover (Rns) and the vines (Rnc) is made considering the exponential form for radiation extinction, with the coefficient of extinction being corrected with a factor dependent on the zenital solar angle (j) while leaf area index (LAI) is corrected with a clumping factor, Ω(φ). Sensible heat flux from the vines (Hc) is calculated from radiative temperature (Tc) considering that the fluxes from the different origins are independent and that there are two resistances in series between the canopy and the atmosphere: the leaf boundary layer resistance (raHc) and the aerodynamic resistance of the crop (raH). Besides the estimation of the daily values of transpiration, the model allows to study the evolution of the different components of the radiation balance throughout the day. The daily evolution of the evaporation fraction from the vines (FEc) can be approximated by a concave curve. Values of FEc > 1 show that, under certain circumstances and periods of the day, energy used for transpiration (lTc) is greater than crop net radiation, which indicates that there are exchanges of energy between the several components of the surface, namely when evaporative demand from the atmosphere is high and there are no soil water restrictions. The model also shows that, regardless of the soil water status, transpiration is a big part of Rn when these values are low (in the beginning of the morning and late afternoon).
- Ecophysiological potential of the Dão terroir for the production of Touriga Nacional red grapesPublication . Pedroso, V.; Gouveia, J. P.; Rodrigues, P.; Alves, I.; Lopes, C.M.Aiming to evaluate the potential of the portuguese Dão winegrowing region for the production of Touriga Nacional (TN) red grapes, climatic, ecophysiological and viticultural data from two different climatic years (2004, wet year and 2005, dry year) are presented and discussed. The data was collected in the control non-irrigated plants of an irrigation experiment installed at the Dão Research Station, Nelas, Portugal. The vineyard is established in a typical granitic soil and trained on a vertical shoot positioning. According to the Géoviticulture Multicriteria Climatic Classification System, the Dão region is classified as temperate/temperate warm for the heliothermal index, with cool nights (night cold index) and moderately dry (dryness index). In 2004 the predawn leaf water potential presented always values higher than -0.2 MPa from flowering to harvest but in 2005 moderate to severe water stress was observed during the ripening period (-0.4 MPa at veraison to -0.6 MPa at harvest). Leaf stomatal conductance and photosynthetic rate displayed a decreasing pattern from flowering to harvest in both years but attained much lower values in the 2005 ripening period as compared to that of 2004. The yield was similar in both years but 2005 showed lower sugar content, similar titratable acidity and a higher anthocyanin berry skin content. Our data shows that the Dão terroir presents a high inter-annual climate variability which has important repercussions on TN responses being the most unfavorable climatic years those were the high temperatures are coincident with water stress during the first half of the ripening period. In those years irrigation should be applied in order to obtain better quality grapes.
- Effect of irrigation on soil water depletion, vegetative growth, yield and berry composition of the grapevine variety Touriga NacionalPublication . Gouveia, J.; Lopes, C.M.; Pedroso, V.; Martins, S.; Rodrigues, P.; Alves, I.
- Effect of vineyard floor management practices on water use: A case study at a terroir of the "Dão" winegrowing region in PortugalPublication . Marques, F.; Pedroso, V.; Rodrigues, P.; Gouveia, J.P.; Monteiro, A.; Lopes, C.M.Aiming to evaluate the effect of vineyard floor management practices on water use and vine performance, a field experiment was carried out at the Dão Wine Research Station, located at Nelas, Center Portugal. The experiment was set up in 2010 in a mature vineyard planted with the red grape variety ‘Touriga Nacional’, using a 2x2 factorial design with the following treatments: inter-row soil management (permanent resident vegetation vs. soil tillage) and undervine floor management (mulch vs. herbicide). In this paper it will be presented data from 2013 growing season (four seasons after experiment setup). The volumetric soil moisture, assessed with a capacitance probe to a 1.5 m depth, showed a decreasing pattern throughout the growing season in all treatments with the resident vegetation presenting lower values as compared to the tillage treatment, while no significant differences were observed between the two undervine floor management practices. From budburst to flowering the resident vegetation treatment showed a higher soil water depletion (up to 1.5 m depth) than the tillage treatment but the relative situation was reversed during the flowering-veraison period, while no significant differences were observed during the ripening period. Vine stem water potential values showed a decreasing pattern along the season attaining very low values during September but with no significant differences between treatments. In general the soil management practices did not significantly affect vine vigor, yield and berry composition however, since these results are only from one season, further data analysis in ongoing in order to allow stronger conclusions.
- Effects of irrigation on the vigour, yield and berry composition of the red variety Touriga Nacional at the Dão winegrowing region, PortugalPublication . Gouveia, J.P.; Pedroso, V.; Rodrigues, P.; Martins, S.; Alves, I.; Lopes, C.M.In a field trial installed at the Centro de Estudos Vitivinícolas do Dão, Nelas, Portugal, the effect of three irrigation treatments on the agronomic behaviour of cv Touriga Nacional (Vitis vinifera L.) were studied during three growing seasons (2006-2008). Three irrigation treatments (DI30 - irrigation with 30% of ETc; DI50 - irrigation with 50% ETc, FI - full irrigation – 100% Etc) were compared to a control non-irrigated treatment (NI). Compared to NI, the deficit irrigation treatments (DI30 & DI50) showed no significant differences on the yield and its components. The full irrigation treatment induced a significantly higher yield due to a higher bunch weight, as compared with the others treatments. Compared to the control, the deficit irrigation treatments presented similar berry composition during all the three seasons. The FI treatment presented, in all seasons, a significantly higher total acidity and a significantly lower Brix and total anthocyanins concentration as compared to the other treatments. The pruning weight and shoot weight increased with the amount of irrigation water applied, but significant differences were found only between the FI and the NI treatments, the last presenting the lowest values. Despite the fact that in the non-irrigated vineyards of the Dão winegrowing region it is very common to observe vine water stress symptoms, mainly during the ripening period, during the three studied seasons (2006-2008), the deficit irrigation treatments showed no advantages relatively to the control non-irrigated. Despite the higher yield produced in the full irrigation, this treatment had the disadvantages of the excessive vine vigour and lower must quality produced.
- Estimação da transpiração da videira a partir da medição da temperatura da superficie da sebe com termómetro de infravermelhosPublication . Rodrigues, P.; Pedroso, V.; Gouveia, J.P.; Martins, S.; Lopes, C.M.; Alves, I.Com o objectivo de validar um modelo para estimar a transpiração da videira a partir da medição da temperatura radiativa da superfície da sebe, instalou-se um ensaio numa vinha da casta Touriga Nacional, localizada na região do Dão no centro de Portugal. O modelo usado tem por base o princípio da partição do balanço energético entre os componentes do coberto do vegetal (videiras, solo e relvado) admitindo-se que, do ponto de vista energético, a sebe e o substrato (solo+relvado) actuam separadamente e em paralelo. Assim, os fluxos de calor latente para atmosfera a partir da sebe (λEc) são determinados a partir dos valores do balanço de radiação da sebe (Rnc) e dos fluxos de calor sensível (Hc). Além de permitir caracterizar a evolução diurna dos componentes do balanço energético da sebe da vinha, conclui-se que o modelo permite uma boa estimação dos valores diários da transpiração
- Estudo comparativo do sistema radicular dos porta-enxertos SO4, 99R e 1103P em Antrossolos de GranitoPublication . Pacheco, C.M.A.; Dias, A.C.; Pedroso, V.; Gouveia, J.P.; Gomes, C.; Martins, S.; Rodrigues, P.; Lopes, C.M.Aproveitando a oportunidade do arranque de um ensaio de comparação de três porta-enxertos (SO4, 99R e 1103P) na casta Touriga Nacional procedeu-se ao estudo do sistema radicular de seis videiras por porta-enxerto. Avaliou-se a distribuição espacial das raízes pelo método do perfil vertical e quantificou-se a biomassa das raízes, do bacelo e do tronco. Os resultados evidenciam os seguintes aspectos: - A máxima concentração de raízes está localizada entre os 20 e os 50cm de profundidade, decrescendo depois acentuadamente com a profundidade até atingir a rocha granítica; - São raras as raízes que atingem a rocha compacta, mas observou-se a existência de raízes muito finas na zona de contacto lítico; - A distribuição radicular é muito irregular de um plano para outro de observação, não obedecendo a nenhum padrão em particular, mas fortemente dependente da compacidade e da localização espacial das unidades morfológicas resultantes do tipo de preparação do solo à plantação; - Não foram identificadas diferenças ou tendências consistentes entre os porta-enxertos testados, nem quanto à biomassa radicular nem em relação à distribuição de raízes em profundidade, nem mesmo quanto ao número de raízes por m2 (densidade); - A meia encosta, com deficiente drenagem na zona de contacto lítico, apresenta para todos os porta-enxertos menor densidade e biomassa radicular quando comparada com as posições de topo e da base da encosta; - A análise das imagens dos cepos revela uma forte assimetria quanto à distribuição espacial das raízes intra e inter porta-enxertos imputáveis à selecção, preparação e técnica de plantação do Bacelo, bem como à técnica de preparação do solo
- Influence of soil water content and atmospheric conditions on leaf water potential in cv. "Touriga Nacional" deep-rooted vineyardsPublication . Rodrigues, P.; Pedroso, V.; Gouveia, J.P.; Martins, S.; Lopes, C.M.; Alves, I.Abstract In this study, the influence of soil and atmosphere conditions on noon and basal leaf water potential of vines ‘‘Touriga Nacional’’ in the Da˜o region submitted to different irrigation treatments is analysed. Both indicators showed to be dependent on environmental conditions at the time of measurement. Leaf water potential at noon of fully watered plants was linearly related with atmospheric conditions, with values registered when vapour pressure deficit (VPD) was higher than approximately 3 kPa being no different from the values registered in stressed plants. Therefore, this indicator cannot be reliably used to distinguish different plant water stress levels when atmospheric conditions induce high evaporative demands. The basal leaf water potential (wb) was also influenced by VPD at the time of measurement for all soil water conditions. In well irrigated plants, it was even possible to establish a baseline that can therefore be used to identify nonwater stressed conditions (wb (MPa) = -0.062–0.0972 VPD (kPa), r2 = 0.78). A good correlation was found between soil humidity and wb. However, more than the average value of the whole thickness of soil monitored, the wb values were dependent on the distribution of soil humidity, with the plants responding to the presence of wet layers.