‘Vermentino’ and ‘Cagnulari’ adaptation responses to the regulated deficit irrigation strategy managed with stem water potential watering thresholds

Recent years of drought in Sardinia have led to productive problems, not only in rainfed vineyards but also in those irrigated with the most diffuse on farm supplemental irrigation strategy. An optimized production could be obtained with the adoption of regulated deficit irrigation strategy (RDI). RDI can be managed by applying watering thresholds based on the measurement of stem water potential (SWP), even if not all the cultivars are suitable for SWP evaluation. Moreover, quality of grapes production could be oriented, depending on the water stress levels induced on plants, according to the oenological objectives. There were carried out two experiments, in order to evaluate the adaptation of ‘Vermentino’ and ‘Cagnulari’ cultivar to RDI, managed with SWP watering thresholds. These three years experiments were set up with a randomized blocks design where each plot was replicated three times, considering two RDI treatments, differentiated by induced water stress level (moderate stress and severe stress) as controlled variability factor. The second goal was to test if the different water stress levels imposed by treatments could affect grape quality production, in such a way that grapes can be potentially addressed to different oenological objectives. Both cultivars resulted suitable for the RDI irrigation management based on SWP watering thresholds. The two different stress conditions, induced by RDI treatments, were recorded on physiological and productive parameters measured. In particular, each RDI treatment produced grapes potentially suitable to obtain the desired style of wine for both cultivars. Especially in drought years, from both cultivars it was possible to improve the on farm irrigation management by applying RDI strategy managed with the SWP irrigation thresholds to obtain an optimal production, compatible with programmed oenological objectives.