Monitoring of Emerging Water Stress Situations by Thermal and Vegetation Indices in Different Almond Cultivars

In recent years, the area dedicated to modern irrigated almond plantations has increased significantly in Spain. However, legal irrigation allocations are lower than maximum water requirements of crop most cases. Therefore, growers forced implement regulated deficit strategies on their farms, applying stress certain resistant phenological periods and avoiding it sensitive periods. Given need monitor status crop, especially stress, objective this work was evaluate sensitivity two UAV-based indicators detect early conditions four cultivars. The field trial conducted during 2020 an experimental orchard, where were established: full (FI), which received 100% (IR), (RDI), 70% IR whole period except kernel-filling stage when 40% IR. UAV flights performed selected dates season. Crop Water Status Index (CWSI) Normalized Difference Vegetation (NDVI) derived from thermal multispectral images, respectively, compared classical indicators, i.e., stem potential (Ψstem), stomatal conductance (gs), photosynthetic rate (AN). Of performed, three corresponded mild a single flight under moderate conditions. Under CWSI not able capture differences between FI RDI trees that observed with Ψstem. conditions, reached showed significant among both treatments. No NVDI response Although NDVI low signal intensity makes index less robust stress. It can be concluded measurements reliable status, although for (mild) levels Ψstem seems preferred option.