Identification of main factors affecting the within-field spatial variability of grapevine phenology and total soluble solids accumulation: towards the vineyard zoning using auxiliary information

International audience; Grapevine phenology and total soluble solids (TSS) accumulation are important information to plan agricultural operation in the vineyards over the season. The study aims at identifying the main environmental factors and related high spatial auxiliary information that could be used to define within-field zones of phenology and TSS accumulation. An experiment was carried out in the Maule Valley, Chile, considering two representative vineyards with different environmental characteristics: vineyard 1 (cv. Cabernet Sauvignon) which presents differences in elevation and vineyard 2 (cv. Chardonnay) which is considered flat. Within each vineyard, a regular sampling grid was defined to perform measurements: phenology, TSS accumulation, plant water status, vegetative expression, yield, soil physical properties and soil apparent electrical conductivity. Observations were made during four and two years respectively for vineyard 1 and 2. The analysis of the results is based on principal component analysis (PCA) to identify the relationships between variables. Results show that factors affecting the spatial variability of phenology and TSS accumulation are different for each vineyard. For vineyard 1, topography is the main factor that affects the spatial variability both in phenology and TSS accumulation. For vineyard 2, the soil apparent electrical conductivity was the most important factor explaining the spatial variability observed in the phenology, while balance between vegetative expression and fruit load affected the TSS accumulation. These results highlight the possibility to define zones of differentiated management in relation to the phenology and TSS accumulation using auxiliary information easy to acquire or available with high spatial resolution.