Impact of irrigation regimes on grapevine yield and water stress indicators assessed by remote sensing

Increasing drought severity and the rising frequency of extreme climate events are expected to make soil water availability a critical limiting factor for grapevine yield and wine quality. This study evaluated the effects of three irrigation regimes on the grapevine cultivar ‘Panonia’ in a two-year field experiment conducted in an organic vineyard in the Belgrade wine-growing region. Drip irrigation treatments included full irrigation at 100% of crop evapotranspiration, deficit irrigation at 50%, and rainfed conditions (without irrigation). Soil moisture and canopy temperature were monitored during the growing season, while a multispectral camera mounted on a UAV was employed to assess the spatial variability of grapevine water status. Based on the multispectral images, vegetation indices (NDVI, GNDVI, OSAVI) were computed for the main phenological stages. Deficit irrigation resulted in the highest yield per vine (2.71 kg·vine⁻¹) and maintained photosynthetic activity and efficient water use, whereas full irrigation promoted larger cluster size, highlighting trade-offs among yield components. Vegetation indices and canopy temperature reliably reflected vine water status and predicted yield across growth stages. Regression analysis indicated that early-season indices moderately predicted final yield, mid-season thermal and water stress indicators were highly predictive, and late-season indices reflected senescence effects. Energy consumption and greenhouse gas emissions were quantified across irrigation regimes, showing that deficit irrigation reduced the carbon footprint while maintaining high yield. These findings indicate that ‘Panonia’ grapevines exhibit relatively high tolerance to water deficit and confirm that integrating UAV-based remote sensing into vineyard management can optimize resource use, enhance productivity, and support climate-smart and sustainable viticulture.