Comparing water relations and stomatal regulation of Touriga Nacional and Syrah...

• Author(s): Lopes, Carlos ; Monteiro, Ana ; Chaves, M.M.
• Date: 2012
• Persistent ID: http://hdl.handle.net/10400.5/5510
• Origin: Repositório da UTL
• Subject(s): grapevine; leaf water potential; photosynthetic rate; stomatal conductance
• Document Type: Conference Object
• Language: English

Description

Proceedings - IX International Terroir Congress, 2012 Aiming to compare the physiological responses of the Portuguese red variety Touriga Nacional (TN) with Syrah (SY), we studied during the 2007 growing season five-year-old grapevines growing in a commercial non-irrigated vineyard located at the Lisbon winegrowing region. Predawn (Ypd) and midday (YM) leaf water potential, leaf stomatal conductance (gs) and photosynthetic rate (A) were periodically measured between fruit set and harvest. Ypd displayed a decreasing pattern throughout the growing cycle from -0.10 MPa at flowering to -0.44 MPa at harvest. Both varieties showed similar values except during the two measurements made in August when TN presented significantly higher values than SY. Ymid also showed a decreasing pattern from the end of June towards harvest date, with significant differences between varieties being observed during the ripening period, with SY showing lower values than TN. A measured either at mid-morning and midday presented, for most part of the cases, lower values in SY than in TN, although the differences were only significant during the ripening period. gs pattern was parallel to A and, in general, the relative differences between varieties mirrored those reported for A. No significant effect of the variety was detected on the relationships between A or gs measured at mid-morning and Ypd. However, when analyzing the set of data collected at midday it was observed that the regression lines of the relationships between A or gs (dependent variables) and Ypd (independent variable) presented a significantly higher slope in SY as compared to those showed by TN. These results show that the rate of decrease of A and gs with the decrease of Ypd was lower in TN than in SY suggesting that the two varieties have different stomatal regulation, with a more “optimistic” behavior in TN.