X-ray tomography: a promising tool to assess the selection of good quality grafted vines

Un’ Area di Viticultura Americana, detta AVA, è una regione vinicola delimitata ed è dis­tinguibile da caratteristiche geografiche i cui confini sono stati definiti da regolamenti. Il sistema AVA rappresenta un ‘accettazione del concetto di terroir (terreno), come dimostra­no gli studi che confermano il carattere regionale dei vini AVA e dalla sviluppo di sub­denominazioni più relazionate al terreno.

Heatwaves or extreme heat events can be particularly harmful to agriculture. Grapevines grown in the Douro winemaking region are particularly exposed to this threat, due to the specificities of the already warm and dry climatic conditions. Furthermore, climate change simulations point to an increase in the frequency of occurrence of these extreme heat events, therefore posing a major challenge to winegrowers in the Mediterranean type climates. The current study focuses on the application of the STICS crop model to assess the potential impacts of heatwaves in grapevine yields over the Douro valley winemaking region. For this purpose, STICS was applied to grapevines using high-resolution weather, soil and terrain datasets over the Douro. To assess the impact of heatwaves, the weather dataset (1989-2005) was artificially modified, generating periods with anomalously high temperatures (+5 ºC), at certain onset dates and with specific durations (from 5 to 9 days). The model was run with this modified weather dataset and results were compared to the original unmodified runs. The results show that heatwaves can have a very strong impact on grapevine yields, strongly depending on the onset dates and duration of the heatwaves. The highest negative impacts may result in a decrease in the yield by up to -35% in some regions. Despite some uncertainties inherent to the current modelling assessment, the present study highlights the negative impacts of heatwaves on viticultural yields in the Douro region, which is critical information for stakeholders within the winemaking sector for planning suitable adaptation measures.

The trial was conducted in variety/rootstock Riesling/Kober 5 BB in the vineyard district of Vrsac. The vineyard was planted in 1996 on a south-facing slope, with rectangular type pruning of 3×1 m. The training system is of symmetric cordon type and mixed type pruning is practiced.

Esca is a grapevine vascular disease with detrimental consequences on vineyard yield and longevity. Recently, esca leaf symptom development has been shown to result in the occlusion of xylem vessels by tyloses in leaves and stems, leading to hydraulic failure. However, little is known regarding the response of xylem anatomy and stem growth to esca in different varieties . Here we studied the impact of esca leaf symptom development on grapevine physiology, stem growth, and xylem anatomy in two widespread cultivars, Cabernet sauvignon and Sauvignon blanc.

As a result of climate change consequences, there is a gap between the times at which the grapes reach the phenolic and the technology maturities.