Abstract
Abstract Measurements of photosynthesis as a function of intercellular CO 2 (A‐C 1 curve) were made on single. attached leaves of Plantago maritima L. while plants were exposed to changes in salinity. Salinity was increased in steps from 50 to 500 mol m ‐3 NaCl and then returned to 50 mol m ‐3 NaCl at two rates, 75 mol m ‐3 (NaCl) day ‐1 (experiment 1) and 150 mol m ‐3 (NaCl) day ‐1 (experiment 2). In experiment one, the CO 2 assimilation rate declined at high CO 2 concentrations, but the initial slope of the A‐C 1 curve was unaffected in young leaves after salinity was increased to 500 mol m ‐3 NaCl. The insensitivity of photosynthesis to increases in CO 2 concentration above air levels was not associated with insensitivity to a reduction in oxygen concentration. In experiment two increasing the rate at which salinity was changed resulted in larger declines in photosynthesis and leaf conductance than were observed in experiment one. Both the initial slope and the CO 2 saturated region of the A‐C 1 curve were substantially reduced at high salinity suggesting that mesophyll biochemical capacity had been inhibited. However, concurrent measurements of photosynthesis as oxygen evolution under 5% CO 2 indicated no effect of increased salinity on photosynthetic capacity. This suggests that the apparent non‐stomatal limitations indicated by A‐C 1 measurements were artifacts caused by strong, nonuniform stomatal closure.
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Claims 9
Claim · model-written summary
At high CO2 in experiment one, assimilation rate declined.
- Taxon
- Plantago maritima L.
Plantago maritimat0 - Outcome
- CO 2 assimilation ratee0
- Direction
- declinede0
- Qualifier
- at high CO 2 concentrationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In experiment one, the CO 2 assimilation rate declined at high CO 2 concentrations”
t0“Plantago maritima L.”
Claim · model-written summary
The initial A-C curve slope in young leaves was unaffected after salinity reached 500 mol m−3 NaCl.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Organ / stage
- young leavese0
- Treatment
- salinity was increased to 500 mol m ‐3 NaCle0
- Outcome
- initial slope of the A‐C 1 curvee0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the initial slope of the A‐C 1 curve was unaffected in young leaves after salinity was increased to 500 mol m ‐3 NaCl”
t0“Plantago maritima L.”
Claim · model-written summary
The lack of photosynthetic response to added CO2 was not associated with insensitivity to reduced oxygen.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Treatment
- a reduction in oxygen concentratione0
- Outcome
- insensitivity of photosynthesis to increases in CO 2 concentratione0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The insensitivity of photosynthesis to increases in CO 2 concentration above air levels was not associated with insensitivity to a reduction in oxygen concentration.”
t0“Plantago maritima L.”
Claim · model-written summary
The faster salinity change in experiment two caused larger declines in photosynthesis than in experiment one.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Treatment
- increasing the rate at which salinity was changede0
- Outcome
- photosynthesise0
- Direction
- larger declinese0
- Comparator
- experiment onee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing the rate at which salinity was changed resulted in larger declines in photosynthesis and leaf conductance than were observed in experiment one”
t0“Plantago maritima L.”
Claim · model-written summary
The faster salinity change in experiment two caused larger declines in leaf conductance than in experiment one.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Treatment
- increasing the rate at which salinity was changede0
- Outcome
- leaf conductancee0
- Direction
- larger declinese0
- Comparator
- experiment onee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increasing the rate at which salinity was changed resulted in larger declines in photosynthesis and leaf conductance than were observed in experiment one”
t0“Plantago maritima L.”
Claim · model-written summary
High salinity reduced the initial slope of the A-C curve.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Treatment
- high salinitye0
- Outcome
- initial slopee0
- Direction
- substantially reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both the initial slope and the CO 2 saturated region of the A‐C 1 curve were substantially reduced at high salinity”
t0“Plantago maritima L.”
Claim · model-written summary
High salinity reduced the CO2-saturated region of the A-C curve.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Treatment
- high salinitye0
- Outcome
- CO 2 saturated region of the A‐C 1 curvee0
- Direction
- substantially reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Both the initial slope and the CO 2 saturated region of the A‐C 1 curve were substantially reduced at high salinity”
t0“Plantago maritima L.”
Claim · model-written summary
Oxygen-evolution measurements under 5% CO2 indicated no effect of increased salinity on photosynthetic capacity.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Treatment
- increased salinitye0
- Outcome
- photosynthetic capacitye0
- Direction
- no effecte0
- Qualifier
- under 5% CO 2e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“concurrent measurements of photosynthesis as oxygen evolution under 5% CO 2 indicated no effect of increased salinity on photosynthetic capacity”
t0“Plantago maritima L.”
Claim · model-written summary
The authors attributed apparent non-stomatal limitations in A-C measurements to strong, nonuniform stomatal closure.
- Taxon
- Plantago maritima L.Plantago maritimat0
- Outcome
- apparent non‐stomatal limitationse0
- Qualifier
- strong, nonuniform stomatal closuree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the apparent non‐stomatal limitations indicated by A‐C 1 measurements were artifacts caused by strong, nonuniform stomatal closure”
t0“Plantago maritima L.”
The same questions in other papers
salinity · physiology: photosynthesis · Plantago maritima (sea plantain)Results agree
1 paper in the same direction as this paper
- negative
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.