Abstract
ozone pollution, water stress, stomata conductance, ozone uptake, clover, OTC.Ozone is a strong oxidizing pollutant which derives by alteration of the photolytic NOx cycle and it accumulates in the troposphere spreading in rural areas and therefore determining injuries on natural vegetation and crops. Since its penetration occurs mainly through stomata, all factors which alter plant-atmosphere relations could be able to modify plant response to ozone. Interaction between ozone and water stress in Mediterranean environment was studied on ozone resistant and sensitive biotypes of white clover, which were grown in charcoal filtered and notfiltered Open Top Chambers in factorial combination with different levels of water supply. Measurements of biomass, leaf area and stomatal conductance were made during the growth period. Ozone injuries were estimated as not-filtered/filtered OTC yield ratio; the stomatal flux of ozone was estimated multiplying stomata conductance x diffusivity ratio between ozone and water vapour (0.613) x ozone hourly concentrations. The hourly values of ozone uptake were cumulated throughout the cropping periods of the two years. In the sensitive biotype, water stress reduced yield losses due to ozone from 38% to 22%, as well as yield losses due to water stress were reduced by the presence of ozone from 43% to 29%, while no interaction between ozone and water stress was observed in the resistant biotype. Biomass yield losses of the sensitive biotype were strictly correlated to cumulated ozone uptake (R2 = 0.99), while biomass yield losses of the resistant biotype were not affected by the ozone fluxes variations created by the treatments. Flux based models could better estimate yield losses due to ozone in Mediterranean environments in which other stresses could be contemporary present; therefore, the new European directives might replace the actual thresholds based on ozone concentration with others based on ozone flux models.
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Claims 7
Claim · model-written summary
In the sensitive white clover biotype, water stress reduced yield losses due to ozone from 38% to 22%.
- Taxon
- White Clover
Trifolium repenst0 - Material
- sensitive biotypee0
- Treatment
- water stresse0
- Outcome
- yield losses due to ozonee0
- Direction
- reducede0
- Value
- 38% to 22%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Two White Clover Biotypes”
e0“In the sensitive biotype, water stress reduced yield losses due to ozone from 38% to 22%”
Claim · model-written summary
In the sensitive white clover biotype, the presence of ozone reduced yield losses due to water stress from 43% to 29%.
- Taxon
- White CloverTrifolium repenst0
- Material
- sensitive biotypee0
- Treatment
- presence of ozonee1
- Outcome
- yield losses due to water stresse1
- Direction
- reducede1
- Value
- 43% to 29%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Two White Clover Biotypes”
e1“as well as yield losses due to water stress were reduced by the presence of ozone from 43% to 29%”
e0“In the sensitive biotype”
Claim · model-written summary
No interaction between ozone and water stress was observed in the resistant white clover biotype.
- Taxon
- White CloverTrifolium repenst0
- Material
- resistant biotypee2
- Treatment
- ozone and water stresse2
- Outcome
- interaction between ozone and water stresse2
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Two White Clover Biotypes”
e2“while no interaction between ozone and water stress was observed in the resistant biotype”
Claim · model-written summary
In the sensitive biotype, biomass yield losses were strictly correlated to cumulated ozone uptake (R2 = 0.99).
- Taxon
- White CloverTrifolium repenst0
- Material
- sensitive biotypee3
- Treatment
- cumulated ozone uptakee3
- Outcome
- Biomass yield lossese3
- Value
- R2 = 0.99e3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Two White Clover Biotypes”
e3“Biomass yield losses of the sensitive biotype were strictly correlated to cumulated ozone uptake (R2 = 0.99)”
Claim · model-written summary
Biomass yield losses of the resistant biotype were not affected by the ozone flux variations created by the treatments.
- Taxon
- White CloverTrifolium repenst0
- Material
- resistant biotypee4
- Treatment
- ozone fluxes variationse4
- Outcome
- biomass yield lossese4
- Direction
- not affectede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Two White Clover Biotypes”
e4“while biomass yield losses of the resistant biotype were not affected by the ozone fluxes variations created by the treatments”
Claim · model-written summary
Flux-based models could better estimate yield losses due to ozone than concentration-based thresholds.
Verbatim
e5“Flux based models could better estimate yield losses due to ozone in Mediterranean environments”
e6“the actual thresholds based on ozone concentration with others based on ozone flux models”
Claim · model-written summary
The European directives might replace concentration-based ozone thresholds with flux-based ones.
- Taxon
- White CloverTrifolium repenst0
- Outcome
- replace the actual thresholds based on ozone concentration with others based on ozone flux modelse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Two White Clover Biotypes”
e6“the new European directives might replace the actual thresholds based on ozone concentration with others based on ozone flux models”
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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.