Assessing inter-intraspecific variability of leaf vulnerability to embolism for 10 alpine Rhododendron species growing in Southwestern China

Abstract

Alpine Rhododendron species are prominent constituents and renowned ornamental plants in alpine ecosystems. Consequently, evaluating the genetic variation in embolism resistance within the genus Rhododendron and predicting their adaptability to future climate change is important. Nevertheless, the assessment of embolism resistance in Rhododendron species remains limited. This investigation aimed to examine leaf vulnerability to embolism across ten alpine Rhododendron species, which are frequently employed as ornamental species in Rhododendron forests in Southwest China. The study analyzed the correlation between embolism resistance and various morphological traits, while also conducting water control experiments to evaluate the relationship between embolism resistance and drought resistance. The outcomes indicated pronounced variations in leaf vulnerability to embolism among species, as reflected by the water potential at 50% of embolized pixels (P₅₀ ). Furthermore, the leaf P₅₀ exhibited a significant positive correlation with vessel diameter (D) (R² = 0.44, P = 0.03) and vessel wall span (b) (R² = 0.64, P = 0.005), while displaying a significant negative correlation with vessel reinforcement ((t/b)² ) (R² = 0.67, P = 0.004). These findings underscore the reliability of selecting species based on embolism vulnerability to preserve the diversity of alpine ecosystems and foster resilience to climate change.