Xylem embolism persists long after drought has ended and should thus have a lasting effect on plants’ ability to recover from severe drought. This assumption was rarely tested, as quantifying the amount of embolism of individual intact trees is difficult, and following recovery would require long-term monitoring, specifically when studying trees.
Our goal was to test the effect of embolism on recovery from drought in a wide population. We exposed 210 Carob seedlings (Ceratonia siliqua), a species with high resistance to embolism, to a gradient of drought durations, and monitored their ability to recover during five months with respect to their embolism level (assessed using micro-computed tomography).
Seedlings that suffered 38% embolism had 50% chance of dying. In the surviving seedlings, stomatal conductance was still inhibited a month after rehydration but recovered after five months to pre-drought levels regardless of the embolism levels. The hydraulic limitations were mostly noticed in the canopy size as five months after rehydration canopy area and the ability to resprout were strongly correlated to the embolism level sustained during drought (but not to the water potential).
Our results suggest that embolism can be fatal even at levels <50% and that maintaining the integrity of the hydraulic system is critical for rapid drought recovery.
