Abstract
Abstract Since most commercially grown soybean plants in the USA are subjected to low or moderate levels of ambient O 3 pollution it is important to understand whether exposure to O 3 influences CO 2 exchange in this species. Therefore, for 8 weeks soybean ( Glycine max cv. Hodgson) plants were exposed to O 3 for 6.8 h daily in controlled environment chambers. Four treatments were used: 0.01, 0.05, 0.09, and 0.13 µ L L −1 O 3 in filtered air. Net photosynthesis (P n ), dark respiration, and chlorophyll content were measured in all treatments for both individual leaves of various ages and for whole plants. Measurements of CO 2 exchange were made nondestructively with an infrared gas analysis system using either plexiglass cuvettes (leaves) or continuously stirred tank reactors (plants). The P n of whole plants was reduced by 10, 11, and 22% in the 0.05, 0.09, and 0.13 µ L L −1 treatments, respectively, compared with the 0.01 µ L L −1 treatment. Among individual leaves of similar ages, exposure to O 3 also resulted in declines in P n and this occurred at all leaf ages. There was a significant linear relationship between P n and O 3 concentration for both individual leaves and for whole plants. Chlorophyll contents of whole plants and individual leaves were also reduced by O 3 exposure. Chlorophyll content and P n were correlated with each other for both individual leaves and whole plants. Changes with leaf age were typical for P n and for chlorophyll content. There was no apparent effect of O 3 treatment on dark respiration. The observed reduction in P n at low levels of O 3 (coupled with reports of O 3 ‐induced reduction in growth and yield) suggests that ambient O 3 pollution in the USA is currently causing decreased P n in field‐grown soybean which can lead to a significant loss in yield.
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Claims 10
Claim · model-written summary
At 0.05 µ L L −1 ozone, whole-plant photosynthesis fell 10% versus 0.01 µ L L −1.
- Taxon
- Soybean
Glycine maxt0 - Treatment
- 0.05e0
- Outcome
- P n of whole plantse0
- Direction
- reducede0
- Value
- 10e0
- Comparator
- 0.01 µ L L −1 treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The P n of whole plants was reduced by 10, 11, and 22% in the 0.05, 0.09, and 0.13 µ L L −1 treatments, respectively, compared with the 0.01 µ L L −1 treatment”
t0“Soybean”
Claim · model-written summary
At 0.09 µ L L −1 ozone, whole-plant photosynthesis fell 11% versus 0.01 µ L L −1.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- 0.09e0
- Outcome
- P n of whole plantse0
- Direction
- reducede0
- Value
- 11e0
- Comparator
- 0.01 µ L L −1 treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The P n of whole plants was reduced by 10, 11, and 22% in the 0.05, 0.09, and 0.13 µ L L −1 treatments, respectively, compared with the 0.01 µ L L −1 treatment”
t0“Soybean”
Claim · model-written summary
At 0.13 µ L L −1 ozone, whole-plant photosynthesis fell 22% versus 0.01 µ L L −1.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- 0.13 µ L L −1e0
- Outcome
- P n of whole plantse0
- Direction
- reducede0
- Value
- 22%e0
- Comparator
- 0.01 µ L L −1 treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The P n of whole plants was reduced by 10, 11, and 22% in the 0.05, 0.09, and 0.13 µ L L −1 treatments, respectively, compared with the 0.01 µ L L −1 treatment”
t0“Soybean”
Claim · model-written summary
Ozone reduced photosynthesis in individual leaves at all leaf ages.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- all leaf agese0
- Treatment
- exposure to O 3e0
- Outcome
- P ne0
- Direction
- declinese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“exposure to O 3 also resulted in declines in P n and this occurred at all leaf ages”
t0“soybean”
Claim · model-written summary
Photosynthesis had a significant linear relationship with ozone concentration in leaves and whole plants.
- Taxon
- soybeanGlycine maxt0
- Treatment
- O 3 concentratione0
- Outcome
- P ne0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant linear relationship between P n and O 3 concentration for both individual leaves and for whole plants”
t0“soybean”
Claim · model-written summary
Ozone reduced chlorophyll in whole plants and individual leaves.
- Taxon
- soybeanGlycine maxt0
- Treatment
- O 3 exposuree0
- Outcome
- Chlorophyll contents of whole plants and individual leavese0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorophyll contents of whole plants and individual leaves were also reduced by O 3 exposure”
t0“soybean”
Claim · model-written summary
Chlorophyll and photosynthesis were correlated in leaves and whole plants.
- Taxon
- soybeanGlycine maxt0
- Compound
- Chlorophyll contente0
- Outcome
- P ne0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorophyll content and P n were correlated with each other for both individual leaves and whole plants”
t0“soybean”
Claim · model-written summary
Photosynthesis and chlorophyll content changed with leaf age.
- Taxon
- soybeanGlycine maxt0
- Organ / stage
- leaf agee0
- Outcome
- P n and for chlorophyll contente0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Changes with leaf age were typical for P n and for chlorophyll content”
t0“soybean”
Claim · model-written summary
Ozone had no apparent effect on dark respiration.
- Taxon
- soybeanGlycine maxt0
- Treatment
- O 3 treatmente0
- Outcome
- dark respiratione0
- Direction
- no apparent effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“no apparent effect of O 3 treatment on dark respiration”
t0“soybean”
Claim · model-written summary
The authors infer ambient ozone currently decreases field soybean photosynthesis and may cause yield loss.
- Taxon
- soybeanGlycine maxe0
- Treatment
- ambient O 3 pollutione0
- Outcome
- P ne0
- Direction
- decreasede0
- Qualifier
- can lead to a significant loss in yielde0
- Setting
- USAe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“ambient O 3 pollution in the USA is currently causing decreased P n in field‐grown soybean which can lead to a significant loss in yield”
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See all 8 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.