Field heterogeneity of soil texture controls leaf water potential spatial distribution in non-irrigated vineyards

Abstract. Grapevine water status exhibits substantial variability even within a single vineyard. Understanding how edaphic, topographic and climatic conditions impact grapevine water status heterogeneity at the field scale, in non-irrigated vineyards, is essential for winemakers as it significantly influences wine quality. This study aimed to quantify the spatial distribution of grapevine leaf water potential (Ψ_leaf) within vineyards and to assess the influence of soil properties heterogeneity, topography and weather on this intra-field variability, in two non-irrigated vineyards during two viticultural seasons. By combining multilinearly vegetation indices from very-high spatial resolution multispectral, thermal and LiDAR imageries collected with unmanned aerial systems, we efficiently and robustly captured the spatial distribution of Ψ_leaf across both vineyards, at different dates. Our results demonstrated that in non-irrigated vineyards, the spatial distribution of Ψ_leaf was mainly governed by the within-vineyard soil hydraulic conductivity heterogeneity (R² up to 0.81), and was particularly marked when the evaporative demand and the soil water deficit increased, since the range of Ψ_leaf was greater, up to 0.73 MPa, in these conditions. However, topographic attributes (elevation and slope) were less related to grapevine Ψ_leaf variability. These findings show that soil properties within-field spatial distribution and weather conditions are the primary factors governing Ψ_leaf heterogeneity observed in non-irrigated vineyards, and their effects are concomitants.