Thresholds for leaf damage due to dehydration: declines of hydraulic function, stomatal conductance and cellular integrity precede those for photochemistry

Department(s)

Natural Science

Document Type

Article

Publication Date

7-1-2019

Keywords

drought stress, leaf hydraulics, photosynthesis, recovery, rehydration, stomatal conductance, turgor loss point, vulnerability

Abstract

Given increasing water deficits across numerous ecosystems world-wide, it is urgent to understand the sequence of failure of leaf function during dehydration. We assessed dehydration-induced losses of rehydration capacity and maximum quantum yield of the photosystem II (F /F ) in the leaves of 10 diverse angiosperm species, and tested when these occurred relative to turgor loss, declines of stomatal conductance g , and hydraulic conductance K , including xylem and outside xylem pathways for the same study plants. We resolved the sequences of relative water content and leaf water potential Ψ thresholds of functional impairment. On average, losses of leaf rehydration capacity occurred at dehydration beyond 50% declines of g , K and turgor loss point. Losses of F /F occurred after much stronger dehydration and were not recovered with leaf rehydration. Across species, tissue dehydration thresholds were intercorrelated, suggesting trait co-selection. Thresholds for each type of functional decline were much less variable across species in terms of relative water content than Ψ . The stomatal and leaf hydraulic systems show early functional declines before cell integrity is lost. Substantial damage to the photochemical apparatus occurs at extreme dehydration, after complete stomatal closure, and seems to be irreversible. v m s leaf leaf s leaf v m leaf

Publication Title

New Phytologist

ISSN

0028646X

E-ISSN

14698137

Volume

223

Issue

1

First Page

134

Last Page

149

DOI

10.1111/nph.15779

PubMed ID

30843202

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