Abstract

To compare water stress tolerance traits between different fruit tree species under the same experimental conditions can provide valuable information for understanding the mechanisms underlying water stress tolerance in a broader sense. This work aimed to determine and compare the water stress tolerance of six fruit tree species typically cultivated in Mediterranean regions, i.e., pomegranate, fig, mandarin, avocado, and two Prunus species ('R40' and 'R20') and evaluate its association with water use and growth under water deficit. Iso-anisohydric behavior (low to high water stress tolerance) was assessed through a multi-trait approach and associated with growth and water use under well-watered and water deficit conditions. Avocado and mandarin were classified as species with stricter stomatal control over water potential, while pomegranate, fig, and Prunus spp. showed a lesser stomatal control. This classification was supported by the multi-traits analysis, which showed that avocado and mandarin, in contrast to the rest of the species, were characterized by more sensitive gas-exchange thresholds. A more isohydric behavior was associated with lower soil water use capacity, but higher root hydraulic conductivity, and a lower growth capacity. Some traits, such as the fraction of transpirable soil water thresholds, root hydraulic conductivity, and residual soil water content, provide valuable information to discriminate between species or genotypes that are better adapted to water deficit conditions. These traits explain the position of the species in the iso-anisohydric spectrum and allow us to understand and develop better strategies for water management in agricultural systems.