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 (Ψleaf) 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 Ψleaf across both vineyards, at different dates. Our results demonstrated that in non-irrigated vineyards, the spatial distribution of Ψleaf 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 Ψleaf was greater, up to 0.73 MPa, in these conditions. However, topographic attributes (elevation and slope) were less related to grapevine Ψleaf variability. These findings show that soil properties within-field spatial distribution and weather conditions are the primary factors governing Ψleaf heterogeneity observed in non-irrigated vineyards, and their effects are concomitants.