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- Influence of pruning system and deficit irrigation on grapevine physiology, yield and grape quality of cv. Sousão (Vitis vinifera L.) growing under Mediterranean conditionsPublication . Barreales, David; Capitão, Susana dos Anjos; Monteiro, Ângela Marina Alves; Andrade, João Verdial; Ribeiro, A.C.Different strategies are currently being sought to mitigate the effects of grapevine summer water stress. Regulated Deficit Irrigation (RDI) is a strategy that has been successfully adapted. Also, some pruning systems have been identified as capable of influencing vine water balance. The aim of this work was to evaluate the effect of two RDI strategies and two pruning systems on grapevine physiology, yield and grape quality of the Sousão variety grown under Mediterranean conditions. This study was conducted in an organic vineyard in northeastern Portugal (41º31´N; 7º5´W; 326 m a.s.l.), planted in 2011 with 1103 P rootstock. The pruning systems, single Cordon and single Guyot were established in 2013. In 2019, three irrigation treatments were implemented: a full irrigation control, FI (100% ETc), and two deficit irrigations treatments, RDI25 (25% ETc) and RDI50 (50% of ETc). During the growing season, grapevine water status and physiological parameters were monitored. At harvest, yield, yield components, and grape composition were evaluated and analyzed. The results showed that the vines under an RDI regime presented significantly lower leaf water potential values than those under FI in both pruning systems. Therefore, the physiological performance was affected by decreasing its stomatal conductance, transpiration, and photosynthesis. However, the lower physiological performance did not significantly affect yield. No significant differences were observed in total soluble solids and total acidity regarding the grape composition. However, there was an increase in anthocyanins and phenolic compounds in grapes with less irrigation.
- Effects of irrigation and collection period on grapevine leaf (Vitis vinifera L. var. Touriga Nacional): Evaluation of the phytochemical composition and antioxidant propertiesPublication . Barreales, David; Malheiro, Ricardo; Pereira, J.A.; Andrade, João Verdial; Bento, Albino; Casquero, Pedro Antonio; Ribeiro, A.C.The cultivation of grapevines (Vitis vinifera L.) has extended worldwide, with great economic importance. From this crop, we can obtain grapes for fresh consumption, raisins, juices, wine, and other derived products. The cultivation of grapevines also generates some byproducts, such as seeds, skins, wood and leaves. The leaves can be removed from the plant, as is common agricultural practice, to improve the production and quality of the grapes at certain periods in the crop cycle. In the present work, the phytochemical composition (total phenols content, hydroxycinnamic acids derivatives and flavonols) and antioxidant potential (reducing power, ABTS and DPPH radical scavenging capacity) of grapevine leaves from cv. Touriga Nacional were evaluated. The studied cultivar was under three severities of regulated deficit irrigation (RDI60, RDI40, and RDI20; providing 60, 40 and 20% of reference evapotranspiration, respectively) and non-irrigation (NI; exclusively rain-fed), in a vineyard located in the Demarcated Douro Region (Portugal). The leaves were collected at three different phenological stages: veraison, maturation, and grape harvest. For the first time, the interactions between different irrigation regimes and the collection period were evaluated on grapevine leaves. The results obtained for the phytochemical composition revealed that increasing irrigation reduced total phenols content, hydroxycinnamic acids derivatives, and flavonols in all of the phenological stages studied. For instance, compared to that of the control treatment (NI), the total phenols content reduced 19% in RDI20 (from 189 mg GAE g−1 to 153 mg GAE g−1), 28% in RDI40 (136 mg GAE g−1), and 33% in RDI60 (127 mg GAE g−1). The antioxidant activity suffered a reduction when the irrigation amount was increased for all assays. Additionally, the antioxidant activity suffered a reduction over time, presenting higher values in veraison. For harvest sampling, the loss of antioxidant activity was more notable, with EC50 values varying between 0.092 mg mL−1 (NI) and 0.187 mg mL−1 (RDI60). Altogether, the results suggest that grapevine leaves are a potential source of natural compounds with valuable antioxidant properties that could be explored by the pharmaceutical, chemical and food industries.
- Avaliação do stresse hídrico em videiras submetidas a diferentes regimes hídricosPublication . Ribeiro, A.C.; Sá, A.; Andrade, João VerdialNas regiões de clima mediterrânico onde as videiras são plantadas sem rega, verificam-se com frequência no Verão situações de elevado stresse hídrico para a planta. Estas surgem como consequência das baixas reservas hídricas do solo, devido às baixas precipitações estivais, elevada temperatura e elevado défice de pressão de vapor. A aplicação de diferentes regimes de rega pode alterar substancialmente a fisiologia da videira afectando desta forma a produção e a composição da uva, sendo, por isso, necessária a sua avaliação. Este estudo, enquadrado num projecto mais amplo de estudo das relações hídricas da vinha, teve como objectivo avaliar, em condições de stresse hídrico acentuado, duas metodologias indicadoras do estado hídrico de videiras submetidas a diferentes regimes hídricos: o potencial hídrico foliar e a temperatura da canópia. Os resultados mostram que potencial hídrico foliar mostrou ser o método mais fiável para avaliar o estado hídrico na videira em condições de stresse hídrico severo evidenciando uma melhor correlação com os parâmetros fisiológicos. A temperatura do copado tende a aumentar com o incremento do stresse hídrico em consequência do encerramento estomático mostrando uma correlação significativa com o potencial hídrico foliar mas correlações não significativas com os parâmetros fisiológicos.
- Efecto del riego deficitario en los cultivares Touriga Nacional y Touriga Franca (Vitis vinifera L.) en la Región Demarcada del Duero (Portugal)Publication . Barreales, David; Andrade, João Verdial; Feliciano, Manuel; Castro, João Paulo; Rodrigues, M.A.; Blanco-Ward, Daniel; Miranda, Ana Isabel; Silveira, Carlos; Monteiro, Alexandra; Lopes, Myriam; Borrego, Carlos S.; Viceto, Carolina; Rocha, Alfredo; Ribeiro, A.C.El principal factor ambiental que limita la producción de uvas en cantidad y calidad en la mayoría de las regiones productoras de vino del mundo es la falta de agua en determinados momentos de su ciclo de cultivo. Así, se están buscando estrategias para mitigar el efecto de la sequía. El riego deficitario (DI) es una de las estrategias que mejores resultados proporciona. Con este tipo de riego se pretende aportar agua en momentos puntuales y en dosis bajas. Este estudio fue realizado durante el año 2017 en una viña comercial situada en la “Região Demarcada do Douro” (Portugal), en dos cultivares, Touriga Nacional y Touriga Franca. Se usó el riego deficitario, 25% de la evapotranspiración de referencia, en comparación con el secano. El objetivo fue evaluar el efecto del riego deficitario en los parámetros fisiológicos y agronómicos de las plantas así como en la producción y la calidad de las uvas y mostos. Los resultados obtenidos indican un gran estrés hídrico en las plantas de secano, reduciéndose la conductancia estomática y la fotosíntesis neta. El riego aumento la producción de uva sin reducir significativamente los parámetros cualitativos del mosto.