S20 - Session O1 - Effect of irrigation and intra-vineyard soil variability on vegetative growth, yield and berry quality of grapevines cv. Sangiovese

Authors: Giacomo Palai *, Simone Priori, Claudio D'Onofrio, Riccardo Gucci, Letizia Tozzini, Giovanni Caruso

Irrigation is becoming crucial for modern viticulture in the Mediterranean regions where climate change is exacerbating the water shortage issue. An experiment was carried out to evaluate the combined effect of irrigation and soil properties on vine water status, vegetative growth, fruit yield and berry quality. Three irrigation regimes were established in a commercial vineyard (cv. Sangiovese): full irrigation (FI, 100% of ET c ), sustained deficit irrigation (DI, 50% of FI) and rainfed (RF, only precipitation). To take into account the slight slope of the vineyard three zones (A, B, C) were identified based on preliminary measurements of stem water potential (SWP). Mapping of soil spatial variability at high detail was carried out by the use of electromagnetic induction sensor, which measure the soil apparent electrical conductivity (ECa) at three depths. The SWP was significantly different between irrigation treatments and the lowest values were measured in zone B, characterized by the lowest values of ECa. Significant differences in Leaf Area Index (LAI) were found between irrigation treatments in zone A (0.74, 0.66, 0.51 in FI, DI and RF vines, respectively) and zone C (0.71, 0.62 and 0.52) but not in zone B where the lowest LAI values were measured (0.59, 0.53 and 0.54). The highest (3.10 kg) and lowest (1.25 kg) yield per vine was measured in FI vines in zone A and DI vines in zone B, respectively. RF vines showed the highest values of berry soluble solids concentration in zone A and C whereas no differences between irrigation treatments were measured in zone B. The berry anthocyanins and flavonol content at harvest was significantly lower in vines grown in the area with the lowest soil ECa values. Our results highlight the importance of defining the spatial variability in the vineyard for a precise irrigation management.