Drought resilience and fruit performance in strawberry tree (Arbutus unedo L.) populations: ecophysiological screening and postharvest behaviour

Climate change is increasing the frequency and intensity of drought and heat events in Mediterranean regions, urging the need for resilient fruit crops that link stress tolerance to relevant fruit quality traits. My PhD project focuses on the strawberry tree (Arbutus unedo L.), an underutilised Mediterranean evergreen fruit species of considerable ecological relevance in Southern Europe, with a recognised capacity to cope with diverse abiotic and biotic constraints. The project objective is to characterise six Italian A. unedo populations in terms of physiological performance under water-limited conditions and fruit quality characteristics. The primary step is to select provenances with contrasting pedoclimatic characteristics and to use calculated climatic indices (e.g., Emberger’s Q2) across an aridity–temperature gradient. These provenances are then screened for constitutive traits under well-watered conditions combining measurements of xylem vulnerability to embolism formation (P50), water-use strategy (e.g., minimum epidermal conductance, g_min; specific leaf area, SLA), and cellular drought tolerance derived from pressure–volume analysis (turgor loss point, TLP; osmotic potential at full turgor, π₀; and modulus of elasticity, ε).  After that, inducible trait modifications are tested under water stress and recovery conditions, monitoring gas exchange, plant water relations, chlorophyll fluorescence parameters, hydraulic resistance, and growth. In parallel,  a core component of the work investigates fruit physiological performance across different ripening stages (identified by skin colour) and during post-harvest storage. Fruits, harvested at the yellow–orange stage, are analysed for respiratory activity using a custom fruit chamber coupled to a LI-COR 6800 system. Post-harvest dynamics are monitored under two storage treatments (ambient temperature vs. 4 °C) and related to quality attributes, including colour development, soluble solids (°Brix), firmness, weight loss, pectin content, sugar profile, and polyphenol-related traits. Within this post-harvest study, the project also considers the use of edible coatings as a practical tool to modulate storage techniques and help preserve the quality attributes of this perishable fruit. Therefore, integrating provenance screening with fruit respiration and post-harvest physiology provides a practical basis for selecting A. unedo genotypes with improved drought resilience and high fruit yield and quality, thereby fostering A. unedo cultivation in Mediterranean areas under a changing climate.