Monitoring vine water status in Douro Region: Long-term physiology, yield and quality studies to decision-support tools
Fernando Alves1*, Jorge Costa1, Paulo Costa1, Carlos Correia2, Berta Gonçalves2, José Moutinho-Pereira2
1ADVID – Association for Development of Viticulture in the Douro, Quinta de Santa Maria, Apt. 137, 5050-106 Godim, Portugal (email: fernando.alves@advid.pt)
2CITAB – Centre for the Research and Technology of Agro-Environmental and Biological Sciences, University of Trás- os-Montes e Alto Douro, 5001-801, Vila Real, Portugal
The Douro Region is located in Northeast Portugal, within the Douro river basin, surrounded by craggy mountains that confer it characteristic Mediterranean-like climate. This region spreads over a total area of approximately 250,000 ha, of which 45,000 are under vine, and it is divided into three sub-regions: Baixo Corgo (BC), Cima Corgo (CC) and Douro Superior (DS). The westernmost BC is the smallest region and it gets the most rainfall. The easternmost DS is the largest of the three sub-regions and it is the most arid region. Especially in this region, grapevine cultivars are exposed to conditions of severe water stress during the summer period, which strongly affects their behavior. In order to mitigate these effects, vine growers introduced the irrigation in their vineyards. However, given the multiple characteristics of the topography, soil, variety and rootstocks and the water resources scarcity, the knowledge of the amount and frequency of the irrigation has been one of the most pertinent issues in the region.
The use of expedite methodologies to assess the water status is essential for vine growers in the near future. The study was conducted between 2002 and 2010, in a commercial vineyard with cultivar Touriga Nacional at Qtª dos Aciprestes (CC and DS interface), growing under 3 water availability regimes: non-irrigated and irrigated (60%
and 30%) of the potential evapotranspiration. In this study were used methodologies to evaluate the leaf and stem water potential and the yield and quality parameters. In several years the photosynthetic productivity was also determined. The main results showed that grapevines experienced a severe water stress with levels of water potential below of the general references. On the other hand, the predawn water potential was confirmed as a powerful tool to evaluate inter and inter-annual variations in grapevine behavior. Also, high levels of irrigation had a strong impact in yield, while a moderate irrigation increased sugar and in some years the anthocyanins contents.
