Proceedings - IX International Terroir Congress, 2012Aiming 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
