Abstract
The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments. Under high irradiance, salinity had no significant effect on the intercellular to ambient CO2 concentration ratio (C i/C a). However, during photosynthesis under limiting irradiance, the maximum quantum efficiency of CO2 fixation decreased under salinity across species, suggesting there is increased leakage of the CO2 delivered to the bundle sheath cells by the C4 pump. Growth under salinity did not affect the maximum intrinsic efficiency of photosystem 2, PS2 (FV/FM) in these species, suggesting salinity had no effect on photosynthesis by inactivation of PS2 reaction centers. Under saline conditions and high irradiance, P N was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on P N in S. densiflora or D. spicata. This inhibition of P N in S. patens and S. alterniflora was not due to an effect on stomatal conductance since the ratio of C i/C a did not decrease under saline conditions. In growth with and without salt, P N was saturated at ∼500 µmol(quantum) m-2 s-1 while J O2 continued to increase up to full sunlight, indicating that carbon assimilation was not tightly coupled to photochemistry in these halophytic species. This increase in alternative electron flow under high irradiance might be an inherent function in these halophytes for dissipating excess energy.
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Claims 11
Claim · model-written summary
Salinity had no significant effect on the intercellular to ambient CO2 concentration ratio under high irradiance in C4 estuarine grasses.
Verbatim
e0“The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments”
e1“Under high irradiance, salinity had no significant effect on the intercellular to ambient CO2 concentration ratio (C i/C a)”
Claim · model-written summary
Salinity decreased the maximum quantum efficiency of CO2 fixation across C4 estuarine grass species under limiting irradiance.
- Taxon
- halotolerant estuarine C4 grassese0
- Treatment
- salinitye2
- Outcome
- the maximum quantum efficiency of CO2 fixatione2
- Direction
- decreasede2
- Qualifier
- under limiting irradiancee2
Not reportedComparator
Verbatim
e0“The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments”
e2“during photosynthesis under limiting irradiance, the maximum quantum efficiency of CO2 fixation decreased under salinity across species”
Claim · model-written summary
Growth under salinity did not affect the maximum intrinsic efficiency of photosystem 2 in C4 estuarine grasses.
- Taxon
- halotolerant estuarine C4 grassese0
- Treatment
- Growth under salinitye3
- Outcome
- the maximum intrinsic efficiency of photosystem 2, PS2 (FV/FM)e3
- Direction
- did not affecte3
Not reportedComparator
Verbatim
e0“The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments”
e3“Growth under salinity did not affect the maximum intrinsic efficiency of photosystem 2, PS2 (FV/FM) in these species”
Claim · model-written summary
Under saline conditions and high irradiance, P N was reduced by 75 % in Spartina patens.
- Taxon
- Spartina patens
Sporobolus pumiluse4 - Treatment
- saline conditionse4
- Outcome
- P Ne4
- Direction
- reducede4
- Value
- 75 %e4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“Under saline conditions and high irradiance, P N was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on P N in S. densiflora or D. spicata”
Claim · model-written summary
Under saline conditions and high irradiance, P N was reduced by 75 % in S. alterniflora.
- Taxon
- S. alterniflora
Sporobolus alternifloruse4 - Treatment
- saline conditionse4
- Outcome
- P Ne4
- Direction
- reducede4
- Value
- 75 %e4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“Under saline conditions and high irradiance, P N was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on P N in S. densiflora or D. spicata”
Claim · model-written summary
Salinity had no effect on P N in S. densiflora.
- Taxon
- S. densifloraSporobolus purpurascense4
- Treatment
- salinitye4
- Outcome
- P Ne4
- Direction
- no effecte4
Not reportedComparator
Verbatim
e4“Under saline conditions and high irradiance, P N was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on P N in S. densiflora or D. spicata”
Claim · model-written summary
Salinity had no effect on P N in Distichlis spicata.
- Taxon
- D. spicata
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Distichlis spicatae4 - Treatment
- salinitye4
- Outcome
- P Ne4
- Direction
- no effecte4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e4“Under saline conditions and high irradiance, P N was reduced by 75 % in Spartina patens and S. alterniflora, whereas salinity had no effect on P N in S. densiflora or D. spicata”
Claim · model-written summary
In S. patens, the P N reduction under salinity was not due to stomatal closure, as the Ci/Ca ratio did not decrease under saline conditions.
- Taxon
- S. patensSporobolus pumiluse5
- Treatment
- saline conditionse5
- Outcome
- the ratio of C i/C ae5
- Direction
- did not decreasee5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“This inhibition of P N in S. patens and S. alterniflora was not due to an effect on stomatal conductance since the ratio of C i/C a did not decrease under saline conditions”
Claim · model-written summary
P N saturated at about 500 µmol(quantum) m-2 s-1 in C4 estuarine grasses with and without salt.
Verbatim
e0“The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments”
e6“In growth with and without salt, P N was saturated at ∼500 µmol(quantum) m-2 s-1 while J O2 continued to increase up to full sunlight, indicating that carbon assimilation was not tightly coupled to photochemistry in these halophytic species”
Claim · model-written summary
J O2 continued to increase up to full sunlight in C4 estuarine grasses.
Verbatim
e0“The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments”
e6“In growth with and without salt, P N was saturated at ∼500 µmol(quantum) m-2 s-1 while J O2 continued to increase up to full sunlight, indicating that carbon assimilation was not tightly coupled to photochemistry in these halophytic species”
Claim · model-written summary
Carbon assimilation was not tightly coupled to photochemistry in these halophytic species.
Verbatim
e0“The effects of salinity (sea water at 0 ‰ versus 30 ‰) on gross rates of O2 evolution (J O2) and net rates of CO2 uptake (P N) were measured in the halotolerant estuarine C4 grasses Spartina patens, S. alterniflora, S. densiflora, and Distichlis spicata in controlled growth environments”
e6“In growth with and without salt, P N was saturated at ∼500 µmol(quantum) m-2 s-1 while J O2 continued to increase up to full sunlight, indicating that carbon assimilation was not tightly coupled to photochemistry in these halophytic species”
The same questions in other papers
salinity · physiology: photosynthesis · Sporobolus purpurascensPositive and negative results
1 in the opposite direction
- positive
salinity · physiology: photosynthesis · Sporobolus pumilusResults agree
1 paper in the same direction as this paper
- negative
salinity · physiology: photosynthesis · Distichlis spicata (saltgrass)Results agree
1 paper in the same direction as this paper
- negative
salinity · physiology: photosynthesis · Sporobolus alterniflorus (smooth cordgrass)Results agree
2 papers in the same direction as this paper
- negative
- 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.