Integrated Irrigation Management for a Pear Orchard Under Mediterranean Semi-Arid Conditions

Abstract

This study evaluated the effect of an integrated irrigation practice (IP), including regulated deficit irrigation (RDI), managed through an IoT-based platform, on a pear orchard (Pyrus communis L., cv. ‘Krystali’) compared to the farmer’s standard practice (FP). Tree response was evaluated through the measurement of tree water relations, leaf physiological functions, biochemical parameters, fruit growth and quality, production, and aerial multispectral NDVI imaging. IP achieved 15.8% water savings, significantly enhancing water-use efficiency and increasing yield per tree. However, IP trees exhibited higher crop water stress index (CWSI) values and lower midday stem water potential (Ψstem) than FP, particularly by late July, indicating progressive water stress. Leaf-level responses revealed morphological and biochemical alterations to drought, including increased leaf mass per area (LMA), dry matter content (DM), and accumulation of proline, alongside declines in chlorophyll pigments. Despite these stress indicators, gas exchange parameters were maintained in IP, possibly due to fruit load modulating source–sink relationships and surpassing stomatal limitations. IP reduced vegetative growth, as evidenced by lower winter pruning material mass, but this did not result in improved fruit quality. IP produced smaller fruit with lower antioxidant activity, polyphenolic content and soluble solids content/acidity ratio, although fruit firmness was improved. UAV-derived NDVI successfully detected changes in canopy structure following summer pruning but did not discriminate between irrigation treatments, indicating that moderate water stress affected tree physiology before producing measurable changes in canopy greenness. The study highlights the need for integrating irrigation management with fruit thinning and careful scheduling to optimize both water productivity and marketable fruit quality in water-scarce pear production areas.