Abstract
Summary 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 v / F m ) in the leaves of 10 diverse angiosperm species, and tested when these occurred relative to turgor loss, declines of stomatal conductance g s , and hydraulic conductance K leaf , including xylem and outside xylem pathways for the same study plants. We resolved the sequences of relative water content and leaf water potential Ψ leaf thresholds of functional impairment. On average, losses of leaf rehydration capacity occurred at dehydration beyond 50% declines of g s , K leaf and turgor loss point. Losses of F v / F m 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 leaf . 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.
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Claims 6
Claim · model-written summary
Losses of leaf rehydration capacity occurred beyond 50% declines of stomatal conductance, leaf hydraulic conductance and turgor loss point.
Verbatim
e1“On average, losses of leaf rehydration capacity occurred at dehydration beyond 50% declines of g s , K leaf and turgor loss point”
e2“10 diverse angiosperm species”
Claim · model-written summary
Losses of Fv/Fm were not recovered with rehydration and occurred after much stronger dehydration.
Verbatim
e1“Losses of F v / F m occurred after much stronger dehydration and were not recovered with leaf rehydration”
e2“10 diverse angiosperm species”
Claim · model-written summary
Tissue dehydration thresholds were intercorrelated across species.
Verbatim
e1“Across species, tissue dehydration thresholds were intercorrelated”
e2“10 diverse angiosperm species”
Claim · model-written summary
Thresholds for each type of functional decline were much less variable across species in relative water content than in leaf water potential.
Verbatim
e1“Thresholds for each type of functional decline were much less variable across species in terms of relative water content than Ψ leaf”
e2“10 diverse angiosperm species”
Claim · model-written summary
Stomatal and leaf hydraulic systems showed early functional declines before cell integrity was lost.
Verbatim
e1“The stomatal and leaf hydraulic systems show early functional declines before cell integrity is lost”
e2“10 diverse angiosperm species”
Claim · model-written summary
Substantial damage to the photochemical apparatus occurred only at extreme dehydration, after complete stomatal closure, and seems to be irreversible.
Verbatim
e1“Substantial damage to the photochemical apparatus occurs at extreme dehydration, after complete stomatal closure, and seems to be irreversible”
e2“10 diverse angiosperm species”