Influence of the winter pruning time on the phenology of some cultivars in the DOCG "Franciacorta" (Lombardy) and the DOC "Montefalco" (Umbria)

The winter pruning of the vine is used to control the level of production of the plant (Iacono et al., 1990) and may also have implications on the quality of the product; it is then better to adopt the technique most appropriate to the enological objective, carrying out various kind of pruning and intervening at the appropriate time for the cultivar growing on the farm. Recent studies on climate change and its possible impact on the lifecycle of the vine revealed that in Europe there is a tendency to the advance of phenological stages (Jones et al., 2005) thus influencing the technological maturity of the grape, allowing to obtain more alcoholic wines. This agronomical techniques can affect the phenology of the vine (Fregoni, 1998); it must also take into account that it may vary depending on the genetic heritage of each variety and vigor of the rootstock (Baldini, 1986). Given the importance that the pruning on vine growth, a study of the most important phenological stages such as budding, leaf development, flowering, fruit setting, veraison (using as reference the BBCH scale) was carried out in the year 2010, with the aim to assess how the pruning realized at different times can lead changes in the phenology of plants. For this reason data collected in two different regions of Italy (Lombardy and Umbria) have been studied taking into account six different cultivars: Chardonnay and Pinot Noir as grapes suitable to become sparkling wines, have been observed in the territory of Franciacorta (BS); Grechetto, Sauvignon Blanc, Sangiovese and Sagrantino have been chosen as a variety of comparison in Montefalco (PG) area. Turfed vineyards with a planting density of 6000 plants, cultivated with spurred cordon grown from about ten years have been observed in all cases; pruning have been made each month from that of November to April. Looking at the first data of phenological stages, Chardonnay shows a delay till flowering for plants pruned during the months of February, March and April; these differences are reduced between fruit setting and veraison, leading to a homogenization of all stages of intervention; the Pinot noir shows a delay for the months of November and April, but this delay is minimal at the veraison. The Sagrantino and Sangiovese grapes recorded a phenological delay in the first three phases (budding, flowering and fruit set), while in the last two (fruit set and veraison) it doesn\u2019t observed differences between the times of intervention. The Grechetto is affected by the different time of pruning showing a delay for all phenological stages in tests pruned in March and April; the Sangiovese didn\u2019t suffer the effects of pruning as it shows a similar behaviour between tests in all growth stages. Also the technological maturity of the grapes was influenced by pruning and, in this case, the varieties had different behaviours depending on the analytical parameter observed: in Franciacorta the delay of pruning in Chardonnay has led to a significant decrease in pH, while the Pinot Noir shows an increase of acidity. In Montefalco the Sauvignon blanc records a significant decrease of the sugar with the delay of pruning, especially in the period of March where it results to be lower than the other months. The Grechetto shows higher acidity in April, while the Sangiovese and Sagrantino have a tendency to decrease the total acidity with the delay of pruning