Management of grapevine water status with the DSS Vintel® provides evidence of sustainable irrigation strategies while maintaining wine quality of Pinot gris in Friuli-Venezia Giulia region, NE italy

Abstract

Context and purpose of the study – 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 (ΨPD).

Material and methods – The DSS Vintel® (decision support system) by the French company ITK, was used during the seasons 2021 and 2022 to create three different irrigation regimes in a Pinot gris vineyard at experimental farm “A. Servadei” of the University of Udine. Three treatments were compared: WW, well-watered, where ΨPD was at -0.2 MPa throughout the season; MS, moderate deficit (flowering-harvest) where ΨPD was reduced to -0.35 MPa; and, SS, severe deficit, (flowering-harvest) where ΨPD was at -0.55 MPa. During both seasons, treatments were irrigated based on recommendations by Vintel®; ΨPD and Ψstem were measured June-August. From veraison to harvest, grape berry samples were collected in triplicate to observe ripening; at harvest yield parameters were assessed. Wine has been made in both seasons: varietal, fermentative aromas, thiols were analysed (GC-MS). Five months after, sensory characters of the wines were evaluated by an expert panel (only for 2021 wines). 

Results – The trends of ΨPD and Ψstem were different between the two seasons, and in 2022 both parameters were more correlated than in 2021 with the imposed deficit irrigation strategies. Both MS and SS treatments resulted in a reduction of average cluster weight and yield. In addition, in 2022 cluster number per plant was reduced in SS, possibly indicating a carry-over effect from the previous season. The accumulation of berry soluble solids was reduced in MS and SS treatments, while no effect was recorded on titratable acidity and pH. The aroma profile (only 2021 wines) was slightly impacted by deficit irrigation. Alcohols and esters were increased in MS, but the most important effect was produced on 3SH concentration, which decreased in more challenging SS. The sensory analysis of 2021 wines did not highlight differences among treatments (to be confirmed in the second season). In summary, this trial yielded interesting results concerning the effect of deficit irrigation on yield, grape quality and wine aroma characteristics. MS resulted as the most sustainable strategy since it could maintain aroma characteristics of wines while reducing water use.