Abstract
The projected rise in atmospheric CO2 concentration is expected to increase growth and yield of many agricultural crops. The magnitude of this stimulus will partly depend on interactions with other components of the atmosphere such as tropospheric O3. Elevated CO2 concentrations often lessen the deleterious effects of O3, but the mechanisms responsible for this response have received little direct examination. Previous studies have indicated that protection against O3 injury by elevated CO2 can be attributed to reduced O3 uptake, while other studies suggest that CO2 effects on anti-oxidant metabolism might also be involved. The aim of this experiment was to test further the roles of O3 flux and antioxidant metabolism in the suppression of O3 injury by elevated CO2. In a two-year experiment, soybean [Glycine max (L.) Merr.] was exposed from emergence to maturity to charcoal-filtered air or charcoal-filtered air plus a range of O3 concentrations in combination with ambient or approximately twice-ambient CO2 concentrations in open-top field chambers. Experimental manipulation of O3 concentrations and estimates of plant O3 uptake indicated that equivalent O3 fluxes that suppressed net photosynthesis, growth, and yield at ambient concentrations of CO2 were generally much less detrimental to plants treated concurrently with elevated CO2. These responses appeared unrelated to treatment effects on superoxide dismutase, glutathione reductase, and peroxidase activities and glutathione concentration. Total ascorbic acid concentration increased by 28-72% in lower canopy leaves in response to elevated CO2 and O3 but not in upper canopy leaves. Increasing concentrations of atmospheric CO2 will likely ameliorate O3 damage to many crops due to reduced O3 uptake, increased carbon assimilation, and possibly as yet undetermined additional factors. The results of this study further suggest that elevated CO2 may increase the threshold O3 flux for biomass and yield loss in soybean.
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Claims 6
Claim · model-written summary
At equivalent ozone fluxes, elevated CO2 reduced detrimental effects on net photosynthesis, growth and yield.
- Taxon
- soybean
Glycine maxt0 - Treatment
- elevated CO2e0
- Outcome
- net photosynthesis, growth, and yielde0
- Direction
- much less detrimentale0
- Comparator
- ambient concentrations of CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“equivalent O3 fluxes that suppressed net photosynthesis, growth, and yield at ambient concentrations of CO2 were generally much less detrimental to plants treated concurrently with elevated CO2.”
t0“in soybean”
Claim · model-written summary
The protective response appeared unrelated to superoxide dismutase, glutathione reductase and peroxidase activities.
- Taxon
- soybeanGlycine maxt0
- Gene
- superoxide dismutase, glutathione reductase, and peroxidasee0
- Outcome
- These responsese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These responses appeared unrelated to treatment effects on superoxide dismutase, glutathione reductase, and peroxidase activities and glutathione concentration.”
t0“in soybean”
Claim · model-written summary
The protective response appeared unrelated to glutathione concentration.
- Taxon
- soybeanGlycine maxt0
- Compound
- glutathione concentratione0
- Outcome
- These responsese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“These responses appeared unrelated to treatment effects on superoxide dismutase, glutathione reductase, and peroxidase activities and glutathione concentration.”
t0“in soybean”
Claim · model-written summary
Elevated CO2 and O3 increased lower-canopy ascorbic acid concentration by 28-72%.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- lower canopy leavese0
- Treatment
- elevated CO2 and O3e0
- Outcome
- Total ascorbic acid concentratione0
- Direction
- increasede0
- Value
- 28-72%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total ascorbic acid concentration increased by 28-72% in lower canopy leaves in response to elevated CO2 and O3 but not in upper canopy leaves.”
t0“in soybean”
Claim · model-written summary
Upper-canopy leaves did not show the ascorbic acid increase.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- upper canopy leavese0
- Treatment
- elevated CO2 and O3e0
- Outcome
- Total ascorbic acid concentratione0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Total ascorbic acid concentration increased by 28-72% in lower canopy leaves in response to elevated CO2 and O3 but not in upper canopy leaves.”
t0“in soybean”
Claim · model-written summary
The authors infer elevated CO2 may raise the ozone-flux threshold for soybean biomass and yield loss.
- Taxon
- soybeanGlycine maxe0
- Treatment
- elevated CO2e0
- Outcome
- threshold O3 flux for biomass and yield losse0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO2 may increase the threshold O3 flux for biomass and yield loss in soybean.”
The same questions in other papers
ozone · quality: phytochemicals · Glycine max (soybean)Results differ
1 paper in the same direction as this paper · 4 in the opposite direction
- no effect
- positive
- no effect
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See all 6 papers →co2 · physiology: photosynthesis · Glycine max (soybean)Results differ
49 papers in the same direction as this paper · 14 in the opposite direction
- no effect
- negative
- no effect
60 papers more in this group
See all 64 papers →co2 · quality: phytochemicals · Glycine max (soybean)Positive and negative results
2 in the opposite direction
- negative
- negative
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.