Influence of Canopy Management Practices on Vineyard Microclimate: Definition of New Microclimatic Indices

Meteorological parameters have a crucial influence on grapevine (Vitis vinifera L.) production quantity and quality. Most of the commonly used bioclimatic indices are not appropriate to represent intravineyard micrometeorological variability, in particular the subdaily dynamics that are important in grape maturation processes. The aim of this research was to compile a new set of micrometeorological indices and evaluate their capacity to discriminate the differences in the microclimatic daily cycle induced by different canopy management techniques, based on a statistical data set of three years (2008, 2009, 2010) of hourly data of cluster internal temperature, canopy air temperature, and solar radiation intercepted by the cluster. Data was collected in four vineyards planted with Sangiovese and Cabernet Sauvignon, located in three climatic zones of Tuscany (Italy). Starting from this data set, some new micrometeorological indices were defined using two different criteria for subdaily time segmentation: static, based on fixed hourly intervals, and dynamic, based on solar height daytime segmentation. Results showed that indices based on subdaily data better provide a better representation of vineyard microclimate than daily indices and are able to highlight microclimatic differences induced by canopy management practices. The indices more sensitive to treatments are those related to the solar radiation intercepted by the cluster parameter and relative to the Broad Daylight Index, which represent the average of micrometeorological parameters in the middle hours of the day. The proposed indices enhance the characterization of micrometeorological conditions induced by different canopy management practices and, therefore, the assessment of the within-vineyard spatial variability of environmental parameters.