Abstract
Steady-state and dynamic gas exchange responses to ozone visible injury were investigated in an ozone-sensitive poplar clone under field conditions. The results were translated into whole tree water loss and carbon assimilation by comparing trees exposed to ambient ozone and trees treated with the ozone-protectant ethylenediurea (EDU). Steady-state stomatal conductance and photosynthesis linearly decreased with increasing ozone visible injury. Dynamic responses simulated by severing of a leaf revealed that stomatal sluggishness increased until a threshold of 5% injury and was then fairly constant. Sluggishness resulted from longer time to respond to the closing signal and slower rate of closing. Changes in photosynthesis were driven by the dynamics of stomata. Whole-tree carbon assimilation and water loss were lower in trees exposed to ambient O(3) than in trees protected by EDU, both under steady-state and dynamic conditions. Although stomatal sluggishness is expected to increase water loss, lower stomatal conductance and premature leaf shedding of injured leaves aggravated O(3) effects on whole tree carbon gain, while compensating for water loss. On average, WUE of trees exposed to ambient ozone was 2-4% lower than that of EDU-protected control trees in September and 6-8% lower in October.
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Claims 9
Claim · model-written summary
Stomatal conductance and photosynthesis decreased linearly with ozone injury.
PopulusOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Steady-state stomatal conductance and photosynthesis linearly decreased with increasing ozone visible injury”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Stomatal sluggishness increased until 5% injury, then was fairly constant.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stomatal sluggishness increased until a threshold of 5% injury and was then fairly constant”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Longer response time and slower closing caused sluggishness.
- Outcome
- Sluggishnesse0
- Qualifier
- longer time to respond to the closing signal and slower rate of closinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sluggishness resulted from longer time to respond to the closing signal and slower rate of closing”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Changes in photosynthesis were driven by stomatal dynamics.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes in photosynthesis were driven by the dynamics of stomata”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Ambient ozone reduced whole-tree carbon assimilation relative to EDU protection.
- Treatment
- ambient O(3)e0
- Outcome
- Whole-tree carbon assimilatione0
- Direction
- lowere0
- Comparator
- trees protected by EDUe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Whole-tree carbon assimilation and water loss were lower in trees exposed to ambient O(3) than in trees protected by EDU, both under steady-state and dynamic conditions”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Ambient ozone reduced whole-tree water loss relative to EDU protection.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Whole-tree carbon assimilation and water loss were lower in trees exposed to ambient O(3) than in trees protected by EDU, both under steady-state and dynamic conditions”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Lower conductance and premature shedding aggravated ozone effects on carbon gain while compensating water loss.
- Outcome
- whole tree carbon gaine0
- Qualifier
- lower stomatal conductance and premature leaf shedding of injured leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“lower stomatal conductance and premature leaf shedding of injured leaves aggravated O(3) effects on whole tree carbon gain, while compensating for water loss”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Ambient ozone lowered WUE by 2-4% in September.
- Treatment
- ambient ozonee0
- Outcome
- WUEe0
- Direction
- lowere0
- Value
- 2-4%e0
- Qualifier
- Septembere0
- Comparator
- EDU-protected control treese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WUE of trees exposed to ambient ozone was 2-4% lower than that of EDU-protected control trees in September”
t0“ozone-sensitive poplar clone under field conditions”
Claim · model-written summary
Ambient ozone lowered WUE by 6-8% in October.
- Treatment
- ambient ozonee0
- Outcome
- WUEe0
- Direction
- lowere0
- Value
- 6-8%e0
- Qualifier
- Octobere0
- Comparator
- EDU-protected control treese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“WUE of trees exposed to ambient ozone was 2-4% lower than that of EDU-protected control trees in September and 6-8% lower in October”
t0“ozone-sensitive poplar clone under field conditions”
The same questions in other papers
ozone · physiology: photosynthesis · Populus (poplar)Results differ
16 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- negative
14 papers more in this group
See all 18 papers →ozone · physiology: water · Populus (poplar)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- 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.