Physiological Traits Combination Shapes Common Strategies of Water and Carbon Use Regulation Across Fruit Tree Species

Crop plants, including fruit trees, are particularly vulnerable to water scarcity because past selection prioritized productivity over drought resistance, making it challenging to maintain productivity with minimal water use in the context of climate change. This study aims to determine which trait combination of 10 fruit tree species influences their water and carbon use, with the goal of understanding their adaptability to water scarcity. The results showed that water stress traits (turgor loss point, TLP; vulnerability index, VI), a carbon-related trait (specific leaf area; SLA), and a biomass allocation trait (Huber value; H_v) define the major axis of variability and present the strongest correlations with other traits. Two distinct strategies emerged: the first, mainly around Prunus species, was characterized by high H_v, low SLA, more negative TLP, and low VI, indicating greater water-stress tolerance due to sapwood redundancy and reduced organ vulnerability. They also exhibited higher maximum photosynthetic rates, indicating greater assimilation rates. The second strategy, mainly including Citrus species, exhibited opposite traits and trends. These trait combinations were likely shaped by shared ancestry and environmental factors. Understanding these correlations can guide irrigation practices and the selection of resilient species, contributing to more robust agricultural systems in a changing climate scenario.