Abstract
SUMMARY Spring wheat ( Triticum aestivum L., cv. Albis) was grown in open‐top chambers and exposed to four different levels of ozone (O 3 ) from the three‐leaf stage until maturity. The aim was to examine changes in leaf and canopy gas exchange, and in chlorophyll fluorescence, in response to O 3 flux. Measurements were carried out periodically between full expansion and complete senescence of flag leaves. Fluxes to the canopy of CO 2 (CER c .) (corrected for soilborne CO 2 ), water vapour (E c ) and O 3 were determined by using open‐top chambers as differential systems. Water use efficiency (WUE c .) was calculated from CER c , and E c . Leaf CO 2 (CER n ) and H 2 O (E n ) exchange rates, stomatal conductance (g,(H 2 O)), and WUE n , were analyzed with a portable gas exchange analyzer. Effects of O 3 flux on structural components of photosynthesis were examined by determining variable fluorescence (defined by the F v /F o ratio) in leaves after 60 minutes of dark‐adaptation or during the night. The decline in CER c and CER n associated with senescence was accelerated by O 3 . Average CER n between flag leaf unfolding and late milk stage declined linearly with increasing O 3 flux. The corresponding decline in average CER c was less pronounced. The quantitative effect of O 3 flux on CER c corresponded well with the effect on grain yield. In young leaves, g s (H 2 O) was reduced in response to O 3 but WUE n was unaffected. With progressing leaf age, WUE n declined. Thus, in the young leaves, O 3 affected the stomata directly and, consequently, limitation of photosynthesis was primarily due to reduced CO 2 diffusion. In contrast, in senescent leaves, the effect of O 3 was mainly due to reduced carboxylation. Compared with WUE n WUE c responded differently to increasing O 3 flux. During O 2 fluxes at above‐ambient levels, WUE C tended to increase rather than to decrease. It is suggested that under O 3 stress, factors controlling WUE at the canopy level differ from those operating at the level of single flag leaves. The decline in F v /F o measured after anthesis was stimulated by O 2 , but no effect of O 3 was detected when F v /F o was measured during the night. This leads to the conclusion that the effect of O 3 on photosynthetic structures is reversible and the reduction in photosynthesis in response to O 3 flux is due to metabolic changes rather than to direct damage to structural components.
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Claims 16
Claim · model-written summary
In spring wheat, CER c accelerated under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)
Triticum aestivumt0 - Treatment
- O 3e0
- Outcome
- CER ce0
- Direction
- acceleratede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decline in CER c and CER n associated with senescence was accelerated by O 3 .”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, CER n accelerated under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- CER ne0
- Direction
- acceleratede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decline in CER c and CER n associated with senescence was accelerated by O 3 .”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, Average CER n declined under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- Average CER ne0
- Direction
- declinede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average CER n between flag leaf unfolding and late milk stage declined linearly with increasing O 3 flux.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, average CER c decline under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Outcome
- average CER ce0
- Direction
- declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The corresponding decline in average CER c was less pronounced.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, g s (H 2 O) reduced under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- g s (H 2 O)e0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In young leaves, g s (H 2 O) was reduced in response to O 3 but WUE n was unaffected.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, WUE n unaffected under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- WUE ne0
- Direction
- unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In young leaves, g s (H 2 O) was reduced in response to O 3 but WUE n was unaffected.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, WUE n declined under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Organ / stage
- leaf agee0
- Outcome
- WUE ne0
- Direction
- declinede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“With progressing leaf age, WUE n declined.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, WUE C increase under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 2e0
- Outcome
- WUE Ce0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During O 2 fluxes at above‐ambient levels, WUE C tended to increase rather than to decrease.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, F v /F o stimulated under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 2e0
- Outcome
- F v /F oe0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decline in F v /F o measured after anthesis was stimulated by O 2 , but no effect of O 3 was detected when F v /F o was measured during the night.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
In spring wheat, F v /F o no effect under the stated ozone or age condition.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- F v /F oe0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The decline in F v /F o measured after anthesis was stimulated by O 2 , but no effect of O 3 was detected when F v /F o was measured during the night.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
Ozone effects on canopy carbon exchange corresponded to effects on grain yield.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3 fluxe0
- Outcome
- effect on grain yielde0
- Qualifier
- CER ce0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The quantitative effect of O 3 flux on CER c corresponded well with the effect on grain yield.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors attribute young leaf photosynthesis limitation to reduced carbon dioxide diffusion following stomatal effects.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- limitation of photosynthesise0
- Qualifier
- reduced CO 2 diffusione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Thus, in the young leaves, O 3 affected the stomata directly and, consequently, limitation of photosynthesis was primarily due to reduced CO 2 diffusion.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors attribute ozone effects in senescent leaves mainly to reduced carboxylation.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- effect of O 3e0
- Qualifier
- reduced carboxylatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In contrast, in senescent leaves, the effect of O 3 was mainly due to reduced carboxylation.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors suggest canopy and single leaf water use efficiency have different controls under ozone stress.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3 stresse0
- Outcome
- WUEe0
- Qualifier
- factors controlling WUE at the canopy level differ from those operating at the level of single flag leavese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“It is suggested that under O 3 stress, factors controlling WUE at the canopy level differ from those operating at the level of single flag leaves.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors infer reversible photosynthetic structural effects of ozone.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3e0
- Outcome
- effect of O 3 on photosynthetic structurese0
- Qualifier
- reversiblee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This leads to the conclusion that the effect of O 3 on photosynthetic structures is reversible and the reduction in photosynthesis in response to O 3 flux is due to metabolic changes rather than to direct damage to structural components.”
t0“spring wheat (Triticum aestivum L.)”
Claim · model-written summary
The authors attribute ozone related photosynthesis reduction to metabolic changes.
- Taxon
- spring wheat (Triticum aestivum L.)Triticum aestivumt0
- Treatment
- O 3 fluxe0
- Outcome
- reduction in photosynthesise0
- Qualifier
- metabolic changese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This leads to the conclusion that the effect of O 3 on photosynthetic structures is reversible and the reduction in photosynthesis in response to O 3 flux is due to metabolic changes rather than to direct damage to structural components.”
t0“spring wheat (Triticum aestivum L.)”
The same questions in other papers
ozone · physiology: water · Triticum aestivum (wheat)Positive and negative results
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ozone · physiology: gas exchange · Triticum aestivum (wheat)Positive and negative results
13 papers in the same direction as this paper · 1 in the opposite direction
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11 papers more in this group
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.