Effect of different deficit irrigation regimens on soil moisture, production parameters of mango (Mangifera indica L.), and spectral vegetation indices in the Mediterranean region of Southern Spain

Mediterranean region is facing a severe water resource crisis, exacerbated by climate change. In recent decades, the region has experienced increased anthropogenic pressure due to population growth, tourism, and urban and agricultural expansion, intensifying competition for water among economic sectors. The agri-food sector is one of the most affected by water scarcity. This presents significant challenges for the sustainability of irrigated crops and underscores the need for efficient irrigation strategies and adaptive mechanisms. Among innovative strategies is deficit irrigation. In this context, to ensure effective water management, it is essential to constantly monitor soil moisture and adapt water conditions to the specific requirements of each crop. Precision agriculture, supported by technologies such as remote sensing and UAVs, plays a fundamental role in this context, enabling detailed crop monitoring and facilitating more efficient irrigation management. This study aims to evaluate the impact of using three different irrigation treatments on mango cultivation, a subtropical crop of growing importance in the Mediterranean region. Specifically, Treatment 1 is based on conventional surface drip irrigation without restrictions; Treatment 2 involves conventional surface drip irrigation with a 65% water reduction; and Treatment 3 uses deep subsurface drip irrigation (20 cm), with a similar water restriction as the previous treatment. The effect on mango cultivation has been evaluated based on: (i) soil moisture, (ii) production data collected during the 2022–2023 growing season on the experimental plot; and (iii) two vegetation indices (NDVI and NDRE) derived from multispectral data collected via two UAV flights at different phenological stages. The results indicate that surface drip irrigation has shown better outcomes in terms of production, yield, and crop quality compared to other treatments involving significant water reductions or subsurface irrigation. Deep deficit irrigation has obtained the worst results in the evaluation of plant production, and yield.