Correlation between agronomic performance and resistance gene in PIWi varieties in the field

Varietal Riesling aroma relies strongly on the formation and liberation of bound aroma compounds. Floral monoterpenes, green C6-alcohols, fruity C13-norisoprenoids and spicy volatile phenols are predominantly bound to disaccharides, which are produced and stored in the grape berry during berry maturation. Grape processing aims to extract maximum amount of the precursors from the berry skin to increase the potential for a strong varietal aroma in the wine. Subsequent yeast selection plays an important part in this process.

Deficit irrigation strategies can be valuable means to improve grape quality while saving important amounts of water. A simple way to use deficit irrigation can be based on irrigating a vineyard with a determined level of crop evapotranspiration. Using a precise physiological parameter indicating water status, irrigation could be managed to maintain a specific pre-dawn leaf water potential.

As an essential element for grapevine development and yield, nitrogen is also involved in the winemaking process and largely affects wine composition. Grape must amino nitrogen deficiency affects the alcoholic fermentation kinetics and alters the development of wine aroma precursors. It is therefore essential to control and optimize nitrogen use efficiency by the plant to guarantee suitable grape nitrogen composition at harvest. Understanding the impact of environmental conditions and cultural practices on the plant nitrogen metabolism would allow us to better orientate our technical choices with the objective of quality and sustainability (less inputs, higher efficiency). This trial focuses on the impact of crop limitation – that is a common practice in European viticulture – on nitrogen distribution in the plant and particularly on grape nitrogen composition. A wide gradient of crop load was set up in a homogeneous plot of Chasselas (Vitis vinifera) in the experimental vineyard of Agroscope, Switzerland. Dry weight and nitrogen dynamics were monitored in the roots, trunk, canopy and grapes, during two consecutive years, using a 15N-labeling method. Grape amino nitrogen content was assessed in both years, at veraison and at harvest. The close relationship between fruits and roots in the maintenance of plant nitrogen balance was highlighted. Interestingly, grape nitrogen concentration remained unchanged regardless of crop load to the detriment of the growth and nitrogen content of the roots. Meanwhile, the size and the nitrogen concentration of the canopy were not affected. Leaf gas exchange rates were reduced in response to lower yield conditions, reducing carbon and nitrogen assimilation and increasing intrinsic water use efficiency. The must amino nitrogen profiles could be discriminated as a function of crop load. These findings demonstrate the impact of plant balance on grape nitrogen composition and contribute to the improvement of predictive models and sustainable cultural practices in perennial crops.

The advent of precision viticulture (PV) has allowed to address problems related to spatial and temporal variability at the within-field scale. Nowadays, several remote and proximal sensing solutions allow description of the existing variability at different temporal and ground resolution through extremely robust soil, vigor, yield, and grape quality maps. In parallel, numerous studies have described grapevine performances within the homogeneous zones and identified soil as main driver of variability. There is a broad consensus that different vigor zones within the same plot may show differential canopy growth, yield and fruit composition, depicting diverse enological potentials and cultural needs.

The undergoing global warming scenario is affecting grapevines phenology, including the timing of berry ripening and harvest date, negatively impacting production and quality. This work reports the crucial role of NAC61, a grapevine NAC transcription factor, in regulating metabolic processes occurring from the onset of ripening onwards. NAC61 high confidence targets mainly represent genes acting on stilbene biosynthesis and regulation, and in osmotic and oxidative/biotic stress-related responses. The direct regulation of the stilbene synthase regulator MYB14, the osmotic stress-related gene DHN1b, and the Botrytis cinerea susceptibility gene WRKY52, were all further validated.