Abstract
Abstract Two cultivars of spring wheat ( Triticum aestivum L. cvs. Alexandria and Hanno) and three cultivars of winter wheat (cvs. Riband, Mercia and Haven) were grown at two concentrations of CO 2 [ambient (355 pmol mol −1 ) and elevated (708 μmol mol −1 )] under two O 3 regimes [clean air (< 5 nmol mol −1 O 3 ) and polluted air (15 nmol mol −1 O 3 at night rising to a midday maximum of 75 nmol mol −1 )] in a phytotron at the University of Newcastle‐upon‐Tyne. Between the two‐leaf stage and anthesis, measurements of leaf gas‐exchange, non‐structural carbohydrate content, visible O 3 damage, growth, dry matter partitioning, yield components and root development were made in order to examine responses to elevated CO 2 and/or O 3 . Growth at elevated CO 2 resulted in a sustained increase in the rate of CO 2 assimilation, but after roughly 6 weeks' exposure there was evidence of a slight decline in the photosynthetic rate (c.‐15%) measured under growth conditions which was most pronounced in the winter cultivars. Enhanced rates of CO 2 assimilation were accompanied by a decrease in stomatal conductance which improved the instantaneous water use efficiency of individual leaves. CO 2 enrichment stimulated shoot and root growth to an equivalent extent, and increased tillering and yield components, however, non‐structural carbohydrates still accumulated in source leaves. In contrast, long‐term exposure to O 3 resulted in a decreased CO 2 assimilation rate (c. ‐13%), partial stomatal closure, and the accumulation of fructan and starch in leaves in the light. These effects were manifested in decreased rates of shoot and root growth, with root growth more severely affected than shoot growth. In the combined treatment growth of O 3 ‐treated plants was enhanced by elevated CO 2 , but there was little evidence that CO 2 enrichment afforded additional protection against O 3 damage. The reduction in growth induced by O 3 at elevated CO 2 was similar to that induced by O 3 at ambient CO 2 despite additive effects of the individual gases on stomatal conductance that would be expected to reduce the O 3 flux by 20%, and also CO 2 ‐induced increases in the provision of substrates for detoxification and repair processes. These observations suggest that CO 2 enrichment may render plants more susceptible to O 3 damage at the cellular level. Possible mechanisms are discussed.
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Claims 15
Claim · model-written summary
Elevated CO2 resulted in a sustained increase in the rate of CO2 assimilation in wheat compared with ambient CO2.
- Taxon
- wheat
Triticum aestivumt0 - Treatment
- elevated CO 2e2
- Outcome
- rate of CO 2 assimilatione2
- Direction
- increasee2
- Qualifier
- sustainede2
- Comparator
- ambiente1
- Setting
- phytotrone3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[ambient (355 pmol mol”
e2“Growth at elevated CO 2 resulted in a sustained increase in the rate of CO 2 assimilation”
e3“in a phytotron at the University”
Claim · model-written summary
After roughly 6 weeks of elevated CO2, photosynthetic rate declined slightly, most markedly in winter cultivars.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- elevated CO 2e2
- Outcome
- photosynthetic ratee4
- Direction
- declinee4
- Qualifier
- most pronounced in the winter cultivarse5
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[ambient (355 pmol mol”
e2“Growth at elevated CO 2 resulted in a sustained increase in the rate of CO 2 assimilation”
e4“after roughly 6 weeks' exposure there was evidence of a slight decline in the photosynthetic rate”
e5“which was most pronounced in the winter cultivars”
Claim · model-written summary
Elevated CO2 decreased stomatal conductance in wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- elevated CO 2e2
- Outcome
- stomatal conductancee6
- Direction
- decreasee6
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[ambient (355 pmol mol”
e2“Growth at elevated CO 2 resulted in a sustained increase in the rate of CO 2 assimilation”
e6“Enhanced rates of CO 2 assimilation were accompanied by a decrease in stomatal conductance”
Claim · model-written summary
Elevated CO2 improved the instantaneous water use efficiency of individual wheat leaves.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- elevated CO 2e2
- Outcome
- instantaneous water use efficiencye7
- Direction
- improvede7
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[ambient (355 pmol mol”
e2“Growth at elevated CO 2 resulted in a sustained increase in the rate of CO 2 assimilation”
e7“which improved the instantaneous water use efficiency of individual leaves”
Claim · model-written summary
CO2 enrichment stimulated shoot and root growth of wheat to an equivalent extent.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- CO 2 enrichmente2
- Outcome
- shoot and root growthe2
- Direction
- stimulatede2
- Qualifier
- to an equivalent extente2
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[ambient (355 pmol mol”
e2“CO 2 enrichment stimulated shoot and root growth to an equivalent extent”
Claim · model-written summary
CO2 enrichment increased tillering and yield components of wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- CO 2 enrichmente2
- Outcome
- tillering and yield componentse3
- Direction
- increasede3
- Comparator
- ambiente1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[ambient (355 pmol mol”
e2“CO 2 enrichment stimulated shoot and root growth to an equivalent extent”
e3“increased tillering and yield components”
Claim · model-written summary
Long-term exposure to O3 decreased the CO2 assimilation rate of wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- exposure to O 3e2
- Outcome
- CO 2 assimilation ratee2
- Direction
- decreasede2
- Comparator
- clean aire1
- Setting
- phytotrone3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[clean air (< 5 nmol mol”
e2“exposure to O 3 resulted in a decreased CO 2 assimilation rate”
e3“in a phytotron at the University”
Claim · model-written summary
O3 caused partial stomatal closure in wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- exposure to O 3e2
- Outcome
- partial stomatal closuree3
- Comparator
- clean aire1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[clean air (< 5 nmol mol”
e2“exposure to O 3 resulted in a decreased CO 2 assimilation rate”
e3“partial stomatal closure, and the accumulation of fructan and starch in leaves”
Claim · model-written summary
O3 increased accumulation of fructan and starch in wheat leaves.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- exposure to O 3e2
- Outcome
- fructan and starch in leavese3
- Direction
- accumulatione3
- Comparator
- clean aire1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[clean air (< 5 nmol mol”
e2“exposure to O 3 resulted in a decreased CO 2 assimilation rate”
e3“partial stomatal closure, and the accumulation of fructan and starch in leaves”
Claim · model-written summary
O3 decreased shoot and root growth of wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- exposure to O 3e2
- Outcome
- shoot and root growthe4
- Direction
- decreasede4
- Comparator
- clean aire1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“[clean air (< 5 nmol mol”
e2“exposure to O 3 resulted in a decreased CO 2 assimilation rate”
e4“decreased rates of shoot and root growth”
Claim · model-written summary
O3 affected root growth more severely than shoot growth in wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- exposure to O 3e1
- Outcome
- root growthe2
- Direction
- more severely affectede2
- Comparator
- shoot growthe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“exposure to O 3 resulted in a decreased CO 2 assimilation rate”
e2“with root growth more severely affected than shoot growth”
Claim · model-written summary
Elevated CO2 enhanced the growth of O3-treated wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- elevated CO 2e2
- Outcome
- growthe1
- Direction
- enhancede2
- Comparator
- O 3e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“In the combined treatment growth of O 3”
e2“was enhanced by elevated CO 2”
Claim · model-written summary
Elevated CO2 gave little additional protection of wheat against O3 damage.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- CO 2 enrichmente1
- Outcome
- protection against O 3 damagee1
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“there was little evidence that CO 2 enrichment afforded additional protection against O 3 damage”
Claim · model-written summary
The growth reduction induced by O3 was similar at elevated and ambient CO2 in wheat.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- O 3 at elevated CO 2e1
- Outcome
- reduction in growthe1
- Direction
- similare1
- Comparator
- O 3 at ambient CO 2e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“The reduction in growth induced by O 3 at elevated CO 2 was similar to that induced by O 3 at ambient CO 2”
Claim · model-written summary
CO2 enrichment may make wheat more susceptible to O3 damage at the cellular level.
- Taxon
- wheatTriticum aestivumt0
- Treatment
- CO 2 enrichmente1
- Outcome
- O 3 damagee1
- Direction
- more susceptiblee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“physiology of wheat (Triticum aestivum L.)”
e1“These observations suggest that CO 2 enrichment may render plants more susceptible to O 3 damage at the cellular level”
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See all 145 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.