Abstract
Three vigor zones, identified in a Barbera vineyard by remote sensing at full canopy, were carefully ground-truthed to determine, over 2 years, the relative weight of soil factors in affecting within-field variability, and to investigate vigor zone influence on dry matter (DM) and nutrient partitioning into different vine organs. Regardless of season, high vigor (HV) achieved stronger vine capacity as total vegetative growth and yield while resulting in markedly less ripened fruits than low vigor (LV) vines. PCA analysis carried out on ten different soil and vine variables clearly separated the three vigor levels and the correlation matrix highlighted that the factors mostly contributing to HV were soil depth, soil K and P concentration, total available water, clay fraction and Nleaf concentration. Conversely, sand fraction was the main marker for LV. When annual DM retrieved in clusters, canes, leaves, and shoot clippings was calculated for each vigor level and expressed as content (i.e. kg/ha) there was a general decreasing trend moving from HV to LV. However, when DM partitioned to each organ was given on a relative basis (i.e. percentage over total) results were similar across vigor levels. Similarly, when nutrients were given as content (e.g. kg or g/ha) out of 120 within-vigor combinations (12 nutrients, 2 seasons, 5 organs), 65 showed a significant difference between HV and LV. Conversely, with data expressed on a concentration basis (i.e. % DM) the number of significant differences between the vigor level means fell to 15. The study strengthens the causal link between soil properties and intra-vineyard spatial variability and clarifies that patterns of dry matter and nutrient partitioning to different vine organs are mildly affected by vine vigor when referred on a relative basis.
Highlights
The simplest definition of terroir is the way the vineyard environment shapes grape and wine quality and uniformity of ripening is still one of its main components (Deloire et al, 2005)
Despite seasonal precipitation from April to September being almost equivalent in the 2 years (288 mm on average), in 2016 abundant precipitation occurred in May and June (85 and 95 mm, respectively) while, in 2017, a significant decrease in precipitation was registered from the end of May and coupled to very high thermal regimes that frequently picked up to 36–37 °C between June and August
A 2 year study conducted to assess and calibrate intra-vineyard spatial variability in a Barbera vineyard block showed that, between vigor zones, differences in vine and berry parameters were strong and stable across two quite different seasons. These differences were very much related to soil and canopy factors that allowed the high vigor (HV) vine behaviour to be clearly separated from MV and low vigor (LV) vines
Summary
The simplest definition of terroir is the way the vineyard environment shapes grape and wine quality and uniformity of ripening is still one of its main components (Deloire et al, 2005). A good way to exemplify the meaning of “uniformity of ripening” is having two different grape batches of equal size (i.e. 300 berries) that, after crushing, would yield a must with a very similar total soluble solids concentration (TSS) (i.e. 24 Brix). If each single berry was processed for TSS, the resulting Gaussian distribution might likely present different variances (σ2) and including varying dispersions around the mean. But a fixed mean, the contribution of both immature and over-ripe berries would increase and alter the traits of the final wine. The same concept holds true for either within-cluster, within-vine and within-vineyard variability and explains why “variability” has been traditionally regarded as a negative feature in vineyard management (Dai et al, 2011)
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