Ugni blanc berry and wine composition impacted by thirteen rootstocks

La véraison, stade intermédiaire du développement de la baie de raisin, correspond au début de la maturation. Aux modifications de coloration de la pellicule sont associées une perte de fermeté, une diminution de l’acidité et une augmentation des teneurs en sucres et pigments ainsi que du volume de la baie. Le stade de véraison des cépages blancs reste difficile à apprécier visuellement. Son évaluation par palpation est subjective et donc sujette à caution.

One of the main consequences of global warming is the rise of the mean temperature. Thus, the heat summation by the plants begins sooner in the early spring, and by cumulating growing degree-days, phenological development tends to happen earlier. However, spring frost is still a recurrent phenomenon causing serious damages to buds and therefore, threatening the harvests of the winegrowers. The wind machine is a solution to protect fruit crops against spring frost that is increasingly used. It is composed of a 10-m mast with a blowing fan at its peak. By tapping into the strength of the nocturnal thermal inversion, it sweeps the crop by propelling warm air above to the ground. Thus, stratification is momentarily suppressed. Furthermore, the continuous action of the machine, alone or in synergy, or the addition of a heater allow the bud to be bathed in a warmer environment. Also, the punctual action of the tower’s warm gust reaches the bud directly at each rotation period. All these actions allow the bud to continuously warm up, but with different intensities and over a different period. Although there is evidence of the effectiveness of the wind machines, the thermal transfers involved in those mechanisms raise questions about their true nature. Field measurements based on ultrasonic anemometers and fast responding thermocouples complemented by laboratory measurements on a reduced scale model allow to characterize both the airflow produced by the wind machine and the local temperature in its vicinity. Those experiments were realized in the vineyard of Quincy, in the framework of the SICTAG project. In the future paper, we will detail the aeraulic characterization of the wind machine and the thermal effects resulting from it and we will focus on how the wind machine warms up the local atmosphere and enables to reduce the freezing risk.

A soil management and vine irrigation trial was carried out for 4 consecutive years from 2020 to 2023 at agroscope’s experimental vineyard in leytron (Valais, Switzerland) with the Chasselas grape variety (clone 14-33/4, grafted on 5bb). Two types of soil maintenance (bare soil with chemical weeding and sown grass) coupled with two water regimes (with and without drip irrigation from flowering to veraison) were compared in a randomized design with four replicates of 10 vines each.

La composition du raisin de la variété Muscat d’Alexandrie a été étudiée dans trois terroirs différents au Nord-Est de la Tunisie (RafRaf, Baddar et Kelibia).
Des échantillons de raisins ont été récoltés à maturité industrielle durant les saisons 2001 et 2002 dans les trois régions citées. Les paramètres pomologiques (poids moyen de la grappe et de la baie) et physico-chimiques

The temperature increase related to ongoing climate changes is causing a progressive anticipation of the ripening time, negatively affecting grape quality at harvest.