Sardinia terroir and Cannonau: a zoning approach to discover an ancient tradition

Cannonau variety is historically grown in a large Sardinia area (Jerzu district) and the vineyards are planted both in the plane and in the sloped hills reaching also 650 m of altitude a.s.l. Thus, in order to discover how climate, soil diversity and growing traditions could account for differences in grape and wine quality, this trial was carried out. Within the area of investigation, eight zones were isolated based on soil characteristics (drainage, depth and texture), altitude and climate. Processing climate data, an important differentiation in temperature and thermal range, was discovered between the vineyards sited in the plane and those located up in the hills. Moreover the plan zones are characterised by a heterogeneity in the distribution of the rainfalls. During 2004 and 2005 grapes were collected from veraison to harvest, and the technological maturity was investigated. An advance in the sugar accumulation and titratable acidity degradation was revealed by comparing the plane with the slopes, and this fact was even more evident with the higher vineyards. A first discrimination emerged between plane and high vineyards: the higher the altitude, the higher the anthocyanin content. The yields (higher in the plan) also contribute to partly explain these results. Opposite to these findings, in 2004 the grapes collected in the plane revealed to be much richer in aroma compounds. This fact is probably to be linked with the particular conformation of the valley that result in an increase of the thermal range at the lower altitudes. The sensory evaluation of the wines obtained processing the grapes collected in the different zones, revealed that a zone fingerprint was maintained. Starting on 2005, measurement of soil humidity was performed, and a relationship with grape quality was ascertained.