Utilizzo di un indice ottico di flavonoli per determinare la variabilità spaziale dell'esposizione dei grappoli nella cv Vermentino

Aim of work: to explore the flavonols spatial variability in the Vermentino cv grapes using a fluorescence optical sensor. Method: optical measurements were performed manually in pre-harvest for two consecutive years (2014 - 2015) using a grid of 15m x 15m, measuring 1 ha vineyard in Tuscany. The geo-referenced measurements of clusters have been reported in colorimetric maps of the flavonols index (FLAV). Given the high reactivity of these compounds to the light radiation, the FLAV index was regarded as an indicator of bunches exposure level. Results: the FLAV gross variation was high (spread about 200%, variation coefficient >=40%) and the maps showed a marked spatial structure following a similar variation pattern in the two years. Two areas with higher and lower bunches exposure were therefore identified with the data segmentation using k-means clustering. Accordingly, the chemical analysis of samplings from the two areas showed that the more exposed bunches had a higher maturity level than those less exposed. These results suggest a zonal management of the vineyard that can be carried out with great accuracy thanks to the high representativeness of optical measurements.