Abstract
The internal conductance to CO2 supply from substomatal cavities to sites of carboxylation poses a large limitation to photosynthesis. It is known that internal conductance is decreased by soil water deficits, but it is not known if it is affected by atmospheric water deficits (i.e. leaf to air vapour pressure deficit, VPD). The aim of this paper was to examine the responses of internal conductance to atmospheric and soil water deficits in seedlings of the evergreen perennial Eucalyptus regnans F. Muell and the herbaceous plants Solanum lycopersicum (formerly Lycopersicon esculentum) Mill. and Phaseolus vulgaris L. Internal conductance was estimated with the variable J method from concurrent measurements of gas exchange and fluorescence. In all three species steady-state stomatal conductance decreased by approximately 30% as VPD increased from 1 kPa to 2 kPa. In no species was internal conductance affected by VPD despite large effects on stomatal conductance. In contrast, soil water deficits decreased stomatal conductance and internal conductance of all three species. Decreases in stomatal and internal conductance under water deficit were proportional, but this proportionality differed among species, and thus the relationship between stomatal and internal conductance differed among species. These findings indicate that soil water deficits affect internal conductance while atmospheric water deficits do not. The reasons for this distinction are unknown but are consistent with soil and atmospheric water deficits having differing effects on leaf physiology and/or root-shoot communication.
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Claims 10
Claim · model-written summary
Higher VPD reduced steady-state stomatal conductance by about 30% in Eucalyptus regnans.
- Taxon
- Eucalyptus regnans
Eucalyptus regnanse1 - Treatment
- VPD increased from 1 kPa to 2 kPae0
- Outcome
- steady-state stomatal conductancee0
- Direction
- decreasede0
- Value
- approximately 30%e0
- Comparator
- 1 kPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all three species steady-state stomatal conductance decreased by approximately 30% as VPD increased from 1 kPa to 2 kPa.”
e1“Eucalyptus regnans F. Muell”
Claim · model-written summary
Higher VPD reduced steady-state stomatal conductance by about 30% in Solanum lycopersicum.
- Taxon
- Solanum lycopersicum
Solanum lycopersicume1 - Treatment
- VPD increased from 1 kPa to 2 kPae0
- Outcome
- steady-state stomatal conductancee0
- Direction
- decreasede0
- Value
- approximately 30%e0
- Comparator
- 1 kPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all three species steady-state stomatal conductance decreased by approximately 30% as VPD increased from 1 kPa to 2 kPa.”
e1“Solanum lycopersicum (formerly Lycopersicon esculentum) Mill.”
Claim · model-written summary
Higher VPD reduced steady-state stomatal conductance by about 30% in Phaseolus vulgaris.
- Taxon
- Phaseolus vulgaris
Phaseolus vulgarise1 - Treatment
- VPD increased from 1 kPa to 2 kPae0
- Outcome
- steady-state stomatal conductancee0
- Direction
- decreasede0
- Value
- approximately 30%e0
- Comparator
- 1 kPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In all three species steady-state stomatal conductance decreased by approximately 30% as VPD increased from 1 kPa to 2 kPa.”
e1“Phaseolus vulgaris L.”
Claim · model-written summary
Higher VPD did not affect internal conductance in Eucalyptus regnans.
- Taxon
- Eucalyptus regnansEucalyptus regnanse1
- Treatment
- VPDe0
- Outcome
- internal conductancee0
- Direction
- In no species was internal conductance affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In no species was internal conductance affected by VPD despite large effects on stomatal conductance.”
e1“Eucalyptus regnans F. Muell”
Claim · model-written summary
Higher VPD did not affect internal conductance in Solanum lycopersicum.
- Taxon
- Solanum lycopersicumSolanum lycopersicume1
- Treatment
- VPDe0
- Outcome
- internal conductancee0
- Direction
- In no species was internal conductance affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In no species was internal conductance affected by VPD despite large effects on stomatal conductance.”
e1“Solanum lycopersicum (formerly Lycopersicon esculentum) Mill.”
Claim · model-written summary
Higher VPD did not affect internal conductance in Phaseolus vulgaris.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise1
- Treatment
- VPDe0
- Outcome
- internal conductancee0
- Direction
- In no species was internal conductance affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In no species was internal conductance affected by VPD despite large effects on stomatal conductance.”
e1“Phaseolus vulgaris L.”
Claim · model-written summary
Soil water deficits decreased stomatal and internal conductance in Eucalyptus regnans.
- Taxon
- Eucalyptus regnansEucalyptus regnanse1
- Treatment
- soil water deficitse0
- Outcome
- stomatal conductance and internal conductancee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“soil water deficits decreased stomatal conductance and internal conductance of all three species.”
e1“Eucalyptus regnans F. Muell”
Claim · model-written summary
Soil water deficits decreased stomatal and internal conductance in Solanum lycopersicum.
- Taxon
- Solanum lycopersicumSolanum lycopersicume1
- Treatment
- soil water deficitse0
- Outcome
- stomatal conductance and internal conductancee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“soil water deficits decreased stomatal conductance and internal conductance of all three species.”
e1“Solanum lycopersicum (formerly Lycopersicon esculentum) Mill.”
Claim · model-written summary
Soil water deficits decreased stomatal and internal conductance in Phaseolus vulgaris.
- Taxon
- Phaseolus vulgarisPhaseolus vulgarise1
- Treatment
- soil water deficitse0
- Outcome
- stomatal conductance and internal conductancee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“soil water deficits decreased stomatal conductance and internal conductance of all three species.”
e1“Phaseolus vulgaris L.”
Claim · model-written summary
The proportional relationship between stomatal and internal conductance decreases under water deficit differed among the three species.
- Taxon
- Eucalyptus regnansEucalyptus regnanse1
- Outcome
- relationship between stomatal and internal conductancee0
- Direction
- differed among speciese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Decreases in stomatal and internal conductance under water deficit were proportional, but this proportionality differed among species, and thus the relationship between stomatal and internal conductance differed among species.”
e1“Eucalyptus regnans F. Muell and the herbaceous plants Solanum lycopersicum (formerly Lycopersicon esculentum) Mill. and Phaseolus vulgaris L.”
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See all 15 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.