Xylem vessel blockages in grape pedicel growing in tropical climate observed by microtomography

Optimizing the use of water and improving irrigation strategies has become increasingly important in most winegrowing countries due to the consequences of climate change, which are leading to more frequent droughts, heat waves, or alteration of precipitation patterns. Optimized irrigation scheduling can only be based on a reliable knowledge of the vineyard water status.

In this context, this work aims at the development of a novel methodology, using a contactless, miniaturized, low-cost NIR spectral tool to monitor (on-the-go) the vineyard water status variability. On-the-go spectral measurements were acquired in the vineyard using a NIR micro spectrometer, operating in the 900–1900 nm spectral range, from a ground vehicle moving at 3 km/h. Spectral measurements were collected on the northeast side of the canopy across four different dates (July 8th, 14th, 21st and August 12th) during 2021 season in a commercial vineyard (3 ha). Grapevines of Vitis vinifera L. Graciano planted on a VSP trellis were monitored at solar noon using stem water potential (Ψs) as reference indicators of plant water status. In total, 108 measurements of Ψs were taken (27 vines per date).

Calibration and prediction models were performed using Partial Least Squares (PLS) regression. The best prediction models for grapevine water status yielded a determination coefficient of cross-validation (r2cv) of 0.67 and a root mean square error of cross-validation (RMSEcv) of 0.131 MPa. This predictive model was employed to map the spatial variability of the vineyard water status and provided useful, practical information towards the implementation of appropriate irrigation strategies. The outcomes presented in this work show the great potential of this low-cost methodology to assess the vineyard stem water potential and its spatial variability in a commercial vineyard.

Local climate characterization is fundamental in terroir description, yet global change perspectives raise questions about its feasibility, since temporal stability cannot be no more assumed for the forthcoming years.

Cover crops are acknowledged to be an interesting tool to produce
higher quality grapes in red varieties, as they generally reduce vine vigour and yield. However, their incidence in white wine quality is not clear, since higher nitrogen availability can play an important positive
role, and cover crops may compete for this nutrient. The possible reduction in available nitrogen can also modify the fermentation processes, as well as the synthesis of aromas in the wine. The aim of this work was to evaluate the long-term effect of a grass cover crop on grape and wine quality.

The use of stems during fermentation is generally avoided due to the herbaceous off-odors they can impart to the wine. [1].

On exposera la distinction et la relation entre: “Etude des milieux”, “Zonage Petit ou Zonage Technique ou Sub Zonage”, “Grand Zonage”, “Délimitation des zones productives” ex.