Abstract
summary White clover plants ( Trifolium repens L. cv. ‘Grasslands Huia’) were exposed to combinations of gaseous pollutants and acid mists for 15 wk. The treatments were (a) charcoal‐filtered air (control), ( b ) 40 ppb SO 2 + 40 ppb NO 2 , (e) 40 ppb O a with additional peaks of 2 × 3 h at 80 ppb and 1 × 1 h at 110 ppb O 3 and ( d ) SO 2 +NO 2 +O 3 (a combination of treatments b and c ), these being combined with acid mist treatments (6 mm wk 1 ) with solutions at pHs of 2.5, 3.5, 4.5 and 5.6. All gaseous pollution treatments resulted in substantial reductions in plant dry weights with additive effects of SO 2 + NO 2 and O 3 in the SO 2 + NO 2 +O 2 treatment. There was a lower dry weight, averaged over all gas pollution treatments, for plants exposed to pH 2.5 compared with pH 4.5 or pH 5.6 mists. An interactive effect of gas x mist treatments revealed that effects of acid mists on plant dry weights were overridden by the more toxic O 3 and SO 2 + NO 2 + O 3 gas exposures. Net photosynthesis was reduced in plants exposed to pH 2.5 and pH 3.5 mists compared with plants exposed to pH 5.6 mist. Rates of stomatal conductance were reduced by exposure to the gaseous pollution treatments but not to acid mists. Water loss was greater after 55 h for leaves detached from plants exposed to all gaseous pollution treatments compared with ones from control plants. There was a greater loss of water from detached leaves exposed to pH 2.5 compared with pH 5.6 mist. The quantities (loads) of S + N in gaseous form resulting in decreased growth of T. repens were calculated to be much lower than those applied in mists with no adverse effects. It is concluded that the concepts of critical levels and critical loads of pollutants need considerable refinement for realistic assessments of the threat of pollutants to vegetation.
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Claims 11
Claim · model-written summary
All gaseous pollution treatments caused substantial reductions in white clover plant dry weights.
- Taxon
- white clover
Trifolium repenst0 - Treatment
- gaseous pollution treatmentse0
- Outcome
- plant dry weightse0
- Direction
- reductionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“All gaseous pollution treatments resulted in substantial reductions in plant dry weights”
Claim · model-written summary
Effects of SO2 + NO2 and of O3 on white clover dry weight were additive in the combined SO2 + NO2 + O3 treatment.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- SO 2 + NO 2 and O 3e0
- Outcome
- plant dry weightse0
- Direction
- additive effectse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“All gaseous pollution treatments resulted in substantial reductions in plant dry weights with additive effects of SO 2 + NO 2 and O 3 in the SO 2 + NO 2 +O 2 treatment”
Claim · model-written summary
Averaged over all gas treatments, white clover plants exposed to pH 2.5 mist had lower dry weight than those exposed to pH 4.5 or pH 5.6 mists.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- pH 2.5e0
- Outcome
- dry weighte0
- Direction
- lowere0
- Comparator
- pH 4.5 or pH 5.6 mistse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“There was a lower dry weight, averaged over all gas pollution treatments, for plants exposed to pH 2.5 compared with pH 4.5 or pH 5.6 mists”
Claim · model-written summary
A gas x mist interaction showed that effects of acid mists on plant dry weights were overridden by the more toxic O3 and SO2 + NO2 + O3 gas exposures.
- Taxon
- white cloverTrifolium repenst0
- Outcome
- effects of acid mists on plant dry weights were overriddene0
- Qualifier
- more toxic O 3 and SO 2 + NO 2 + O 3 gas exposurese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“An interactive effect of gas x mist treatments revealed that effects of acid mists on plant dry weights were overridden by the more toxic O 3 and SO 2 + NO 2 + O 3 gas exposures”
Claim · model-written summary
Net photosynthesis was reduced in white clover exposed to pH 2.5 and pH 3.5 mists compared with pH 5.6 mist.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- pH 2.5 and pH 3.5 mistse0
- Outcome
- Net photosynthesise0
- Direction
- reducede0
- Comparator
- pH 5.6 miste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“Net photosynthesis was reduced in plants exposed to pH 2.5 and pH 3.5 mists compared with plants exposed to pH 5.6 mist”
Claim · model-written summary
Stomatal conductance rates were reduced by the gaseous pollution treatments.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- gaseous pollution treatmentse0
- Outcome
- Rates of stomatal conductancee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“Rates of stomatal conductance were reduced by exposure to the gaseous pollution treatments”
Claim · model-written summary
Stomatal conductance rates were not reduced by exposure to acid mists.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- acid mistse0
- Outcome
- Rates of stomatal conductancee0
- Direction
- no_changeinferrede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“Rates of stomatal conductance were reduced by exposure to the gaseous pollution treatments but not to acid mists”
Claim · model-written summary
Detached leaves from plants exposed to all gaseous pollution treatments lost more water after 55 h than leaves from control plants.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- gaseous pollution treatmentse0
- Outcome
- Water losse0
- Direction
- greatere0
- Comparator
- control plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“Water loss was greater after 55 h for leaves detached from plants exposed to all gaseous pollution treatments compared with ones from control plants”
Claim · model-written summary
Detached leaves exposed to pH 2.5 mist lost more water than those exposed to pH 5.6 mist.
- Taxon
- white cloverTrifolium repenst0
- Treatment
- pH 2.5e0
- Outcome
- loss of watere0
- Direction
- greatere0
- Comparator
- pH 5.6 miste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“There was a greater loss of water from detached leaves exposed to pH 2.5 compared with pH 5.6 mist”
Claim · model-written summary
The loads of S + N in gaseous form that decreased growth of T. repens were calculated to be much lower than the loads applied in mists with no adverse effects.
- Taxon
- T. repensTrifolium repense0
- Outcome
- quantities (loads) of S + N in gaseous form resulting in decreased growthe0
- Qualifier
- much lower than those applied in mists with no adverse effectse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The quantities (loads) of S + N in gaseous form resulting in decreased growth of T. repens were calculated to be much lower than those applied in mists with no adverse effects”
Claim · model-written summary
The authors conclude that the concepts of critical levels and critical loads of pollutants need considerable refinement for realistic assessment of the threat to vegetation.
- Taxon
- white cloverTrifolium repenst0
- Outcome
- critical levels and critical loads of pollutants need considerable refinemente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“white clover”
e0“the concepts of critical levels and critical loads of pollutants need considerable refinement”
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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.