Abstract
SUMMARY The effects of mixtures of ozone and carbon dioxide on growth and physiology of an O 3 ‐sensitive (NC‐S) and an O 3 ‐resistant (NC‐R) clone of white clover (Trifolium repens L.) were determined. The experiment was performed in a greenhouse with O 3 treatments of 5 and 82 nl l −1 (ppb) for 6 h d −1 and CO 2 treatments of 380 (ambient), 490,600, and 710 μl l −1 (ppm) for 24 h d −1 . Enrichment with CO 2 decreased foliar gas exchange (measured as stomatal resistance) of NC‐R more than that of NC‐S whereas O 3 decreased gas exchange of NC‐S more than that of NC‐R. Ozone caused extensive foliar injury of NC‐S but caused only slight injury of NC‐R. CO 2 enrichment suppressed O 3 ‐induced foliar injury of NC‐S as measured after 4 wk of exposure, but this effect diminished after 8 wk of exposure. CO 2 enrichment decreased the relative chlorophyll content (μg of chlorophyll mg −1 of leaf tissue sampled) but not the total chlorophyll (total chlorophyll in the leaves sampled). There were no O 3 × CO 2 interactions for foliar chlorophyll. High concentrations of CO 2 caused reddening of new leaves near the end of the 8 wk exposure period. CO 2 enrichment decreased foliar concentrations of N, P, K, S, Cu, B, and Fe, increased foliar concentrations of Mn, but did not affect Zn, Ca, or Mg. Ozone exposure did not modify the CO 2 effects on foliar nutrient concentration. Ozone decreased growth of NC‐S but not NC‐R while CO 2 enrichment stimulated growth of both clones. The highest CO 2 concentration appeared to decrease the effects of O 3 on growth of NC‐S. However, except for a transitory effect on foliar injury, there was no evidence that CO 2 , at concentrations less than the highest used in this study, will protect white clover from the effects of tropospheric O 3 .
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Claims 20
Claim · model-written summary
Carbon dioxide enrichment reduced gas exchange more in NC‐R than NC‐S.
- Taxon
- white clover
Trifolium repenst0 - Material
- NC‐Re0
- Treatment
- CO 2e0
- Outcome
- foliar gas exchangee0
- Direction
- decreasede0
- Comparator
- NC‐Se0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Enrichment with CO 2 decreased foliar gas exchange (measured as stomatal resistance) of NC‐R more than that of NC‐S”
t0“white clover”
Claim · model-written summary
Ozone reduced gas exchange more in NC‐S than NC‐R.
- Taxon
- white cloverTrifolium repenst0
- Material
- NC‐Se0
- Treatment
- O 3e0
- Outcome
- gas exchangee0
- Direction
- decreasede0
- Comparator
- NC‐Re0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“O 3 decreased gas exchange of NC‐S more than that of NC‐R”
t0“white clover”
Claim · model-written summary
Ozone extensively injured NC‐S foliage.
- Taxon
- white cloverTrifolium repenst0
- Material
- NC‐Se0
- Treatment
- Ozonee0
- Outcome
- foliar injurye0
- Comparator
- NC‐Re0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone caused extensive foliar injury of NC‐S but caused only slight injury of NC‐R.”
t0“white clover”
Claim · model-written summary
Ozone caused slight injury to NC‐R foliage.
- Taxon
- white cloverTrifolium repenst0
- Material
- NC‐Re0
- Treatment
- Ozonee0
- Outcome
- slight injurye0
- Comparator
- NC‐Se0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone caused extensive foliar injury of NC‐S but caused only slight injury of NC‐R.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment suppressed ozone injury of NC‐S after four weeks, with diminished suppression after eight.
- Taxon
- white cloverTrifolium repenst0
- Material
- NC‐Se0
- Treatment
- CO 2 enrichmente0
- Outcome
- O 3 ‐induced foliar injurye0
- Direction
- suppressede0
- Qualifier
- after 4 wk of exposuree0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment suppressed O 3 ‐induced foliar injury of NC‐S as measured after 4 wk of exposure, but this effect diminished after 8 wk of exposure.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment decreased relative chlorophyll content.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- relative chlorophyll contente0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased the relative chlorophyll content (μg of chlorophyll mg −1 of leaf tissue sampled) but not the total chlorophyll”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment did not decrease total chlorophyll.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- total chlorophylle0
- Direction
- note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased the relative chlorophyll content (μg of chlorophyll mg −1 of leaf tissue sampled) but not the total chlorophyll”
t0“white clover”
Claim · model-written summary
There was no ozone by carbon dioxide interaction for foliar chlorophyll.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- O 3 × CO 2e0
- Outcome
- foliar chlorophylle0
- Direction
- noe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no O 3 × CO 2 interactions for foliar chlorophyll.”
t0“white clover”
Claim · model-written summary
High carbon dioxide reddened new leaves near the end of eight weeks.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- High concentrations of CO 2e0
- Outcome
- reddening of new leavese0
- Qualifier
- 8 wk exposure periode0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High concentrations of CO 2 caused reddening of new leaves near the end of the 8 wk exposure period.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment decreased foliar N, P and K concentrations.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- foliar concentrations of N, P, Ke0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased foliar concentrations of N, P, K, S, Cu, B, and Fe, increased foliar concentrations of Mn, but did not affect Zn, Ca, or Mg.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment decreased foliar S, Cu and B concentrations.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- S, Cu, Be0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased foliar concentrations of N, P, K, S, Cu, B, and Fe, increased foliar concentrations of Mn, but did not affect Zn, Ca, or Mg.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment decreased foliar Fe concentration.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- Fee0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased foliar concentrations of N, P, K, S, Cu, B, and Fe, increased foliar concentrations of Mn, but did not affect Zn, Ca, or Mg.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment increased foliar Mn concentration.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- foliar concentrations of Mne0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased foliar concentrations of N, P, K, S, Cu, B, and Fe, increased foliar concentrations of Mn, but did not affect Zn, Ca, or Mg.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment did not affect foliar Zn, Ca or Mg concentration.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- Zn, Ca, or Mge0
- Direction
- did not affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“CO 2 enrichment decreased foliar concentrations of N, P, K, S, Cu, B, and Fe, increased foliar concentrations of Mn, but did not affect Zn, Ca, or Mg.”
t0“white clover”
Claim · model-written summary
Ozone did not modify carbon dioxide effects on foliar nutrients.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- Ozone exposuree0
- Outcome
- CO 2 effects on foliar nutrient concentratione0
- Direction
- did not modifye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone exposure did not modify the CO 2 effects on foliar nutrient concentration.”
t0“white clover”
Claim · model-written summary
Ozone decreased growth of NC‐S.
- Taxon
- white cloverTrifolium repenst0
- Material
- NC‐Se0
- Treatment
- Ozonee0
- Outcome
- growthe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone decreased growth of NC‐S but not NC‐R while CO 2 enrichment stimulated growth of both clones.”
t0“white clover”
Claim · model-written summary
Ozone did not decrease growth of NC‐R.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone decreased growth of NC‐S but not NC‐R while CO 2 enrichment stimulated growth of both clones.”
t0“white clover”
Claim · model-written summary
Carbon dioxide enrichment stimulated growth of both clones.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- CO 2 enrichmente0
- Outcome
- growth of both clonese0
- Direction
- stimulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ozone decreased growth of NC‐S but not NC‐R while CO 2 enrichment stimulated growth of both clones.”
t0“white clover”
Claim · model-written summary
Highest carbon dioxide concentration appeared to lessen ozone growth effects in NC‐S.
- Taxon
- white cloverTrifolium repenst0
- Material
- NC‐Se0
- Treatment
- highest CO 2 concentratione0
- Outcome
- effects of O 3 on growthe0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The highest CO 2 concentration appeared to decrease the effects of O 3 on growth of NC‐S.”
t0“white clover”
Claim · model-written summary
Authors found no evidence that lower carbon dioxide concentrations protect clover against tropospheric ozone.
- Taxon
- white cloverTrifolium repense0
- Outcome
- protect white clover from the effects of tropospheric O 3e0
- Direction
- no evidencee0
- Qualifier
- at concentrations less than the highest used in this studye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there was no evidence that CO 2 , at concentrations less than the highest used in this study, will protect white clover from the effects of tropospheric O 3”
The same questions in other papers
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See all 14 papers →co2 · physiology: gas exchange · Trifolium repens (white clover)Results agree
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ozone · crop injury · Trifolium repens (white clover)Results agree
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ozone · growth · Trifolium repens (white clover)Results agree
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See all 6 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.