Key message: Both stem and leaf tissues act as coordinated capacitors releasing water into the transpiration stream to delay xylem embolism. The olive tree (Olea europaea L.) is becoming increasingly topical in plant hydraulics because of its physiological characteristics to cope with drought. Rodriguez-Dominguez et al. (2018) recently found that the coordination in olive of disparate organs like leaves and roots can significantly contribute to a marked stem xylem resistance reaching P50 values of ca. -6 MPa. Although such safety margin is well known, there is a lack of the knowledge about the effect of water that is released from surrounding tissues into the xylem (so-called hydraulic capacitance; kg MPa-1 m-3), which contributes to guarantee plant hydraulic performance under drought stress. Moreover, the gradient of water potential that transpiration path creates from the leaves throughout the plant hydraulic system suggests a coordination between the hydraulic capacitance of leaf and stem tissues. To this end, we will present the results of drought-induced embolism in two-year old olive seedlings submitted to bench-top dehydration. The hydraulic capacitance of the stems, derived from desorption curves, and that of leaves, quantified from pressure-volume curves, were compared with xylem embolism formation, estimated from stem vulnerability curves.

Comunicación presentada en el XIM4 4th Xylem International Meeting Padua, 25-27 September 2019

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