Sensitivity of Trunk Diameter Fluctuations in Vitis vinifera L. Tempranillo and Cabernet Sauvignon Cultivars

Abstract

The effects of different applied water amounts on the behavior of parameters derived from trunk diameter fluctuations (TDF) were studied during three consecutive seasons (2004 to 2006) in a mature vineyard planted with Vitis vinifera cv. Tempranillo and cv. Cabernet Sauvignon in Albacete (Castilla-La Mancha, Spain). Maximum daily trunk shrinkage (MDS) was calculated from TDF. The response of MDS to different irrigation treatments varied in the amplitude of the signal between the two cultivars. MDS of cv. Tempranillo was significantly higher than that of cv. Cabernet Sauvignon in the period before veraison for the three experimental years. MDS decreased in magnitude after veraison regardless of irrigation treatment and tended to be similar in the two varieties, except for one year where there were cultivar differences in yield caused by differential effects of a frost. Irrigation treatment differences in MDS were significant in 2004 and 2005 at pre and post-veraison, while in 2006 they were non-significant possibly due to the very little yield caused by a late frost which affected differentially the cultivars, thus suggesting that yield level may be another factor to consider when attempting to use MDS for irrigation management. Therefore, it appears that the use of trunk diameter sensors for irrigation scheduling in wine grapes would require a specific calibration for the different cultivars.