Interannual assessment of intra-vineyard variability through NDVI-based zoning in a mediterranean environment

This study characterised intra-vineyard vigour variability and assessed its spatial and temporal stability under Mediterranean conditions, through the evaluation of (i) interannual stability of vigour patterns, (ii) their intra-annual evolution across two phenological stages using NDVI, and (iii) the agronomic consistency of NDVI-based vigour classes. UAV multispectral surveys were conducted at BBCH 75 and BBCH 85 in 2022–2023. Six monitoring areas identified based on preliminary NDVI maps were grouped into three vigour classes: high (HV), medium (MV), and low (LV). For each vigour class, vegetative growth, pruning wood weight, stem water potential, yield components, grape composition, and soil properties were characterized. NDVI–vigour relationships and differences among classes were assessed through ANOVA and regression analyses. NDVI values differed between vigour classes and showed no significant year effect, confirming a stable spatial pattern across seasons. However, NDVI changed markedly between BBCH 75 and BBCH 85, indicating that acquisition timing strongly influenced canopy spectral responses, although the relative ranking among classes (HV > MV > LV) remained consistent. HV and MV had finer textured soils, higher organic matter, and greater water-holding capacity, whereas LV had reduced soil available water and more days under stress. LV vines exhibited smaller leaf area, more negative stem water potential, lower berry weight, and reduced yield. LV grapes also had higher TSS and pH, and lower acidity. Stable NDVI-based vigour patterns reflected significant differences in soil properties, vine performance, and grape composition, highlighting the potential of this approach for improving precision management in Mediterranean vineyards.