A clear trade‐off between leaf hydraulic efficiency and safety in an aridland shrub during regrowth.

It has been suggested that a trade‐off between hydraulic efficiency and safety is related to drought adaptation across species. However, whether leaf hydraulic efficiency is sacrificed for safety during woody resprout regrowth after crown removal is not well understood. We measured leaf water potential (ψleaf) at predawn (ψpd) and midday (ψmid), leaf maximum hydraulic conductance (Kleaf‐max), ψleaf at induction 50% loss of Kleaf‐max (KleafP50), leaf area‐specific whole‐plant hydraulic conductance (LSC), leaf vein structure and turgor loss point (πtlp) in 1‐ to 13‐year‐old resprouts of the aridland shrub (Caragana korshinskii). ψpd was similar, ψmid and KleafP50 became more negative, and Kleaf–max decreased in resprouts with the increasing age; thus, leaf hydraulic efficiency clearly traded off against safety. The difference between ψmid and KleafP50, leaf hydraulic safety margin, increased gradually with increasing resprout age. More negative ψmid and KleafP50 were closely related to decreasing LSC and more negative πtlp, respectively, and the decreasing Kleaf‐max arose from the lower minor vein density and the narrower midrib xylem vessels. Our results showed that a clear trade‐off between leaf hydraulic efficiency and safety helps C. korshinskii resprouts adapt to increasing water stress as they approach final size. A trade‐off between leaf hydraulic efficiency and safety is proposed to be related to drought adaptation, but it is still under debate. Here, leaf hydraulic efficiency clearly traded off against safety in resprouts of Caragana korshinskii, thus helping resprouts adapt to increasing water stress. [ABSTRACT FROM AUTHOR]