Abstract
Two rice ( Oryza sativa L.) cultivars of contrasting morphologies, IR‐36 and Fujiyama‐5, were exposed to ambient (360 μl l −1 ) and ambient plus 300 μl l −1 CO 2 from time of emergence until ca 50% grain fill at the Duke University Phytotron, Durham, North Carolina. Exposure to increased CO 2 resulted in about a 50% increase in the photosynthetic rate for both cultivars and photosynthetic enhancement was still evident after 3 months of exposure to a high CO 2 environment. The photosynthetic response at 5% CO 2 and the response of CO 2 assimilation (A) to internal CO 2 (C i ) suggest a reallocation of biochemical resources from RuBP carboxylation to RuBP regeneration. Increases in total plant biomass at elevated CO 2 were approximately the same in both cultivars, although differences in allocation patterns were noted in root/shoot ratio. Differences in reproductive characteristics were also observed between cultivars at an elevated CO 2 environment with a significant increase in harvest index for IR‐36 but not for Fujiyama‐5. Changes in carbon allocation in reproduction between these two cultivars suggest that lines of rice could be identified that would maximize reproductive output in a future high CO 2 environment.
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Claims 6
Claim · model-written summary
Elevated CO2 increased photosynthetic rate about 50% in both cultivars, persisting after three months.
- Taxon
- rice
Oryza sativat0 - Treatment
- increased CO 2e0
- Outcome
- photosynthetic ratee0
- Direction
- increasee0
- Value
- about a 50%e0
- Qualifier
- after 3 months of exposuree0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Exposure to increased CO 2 resulted in about a 50% increase in the photosynthetic rate for both cultivars and photosynthetic enhancement was still evident after 3 months of exposure to a high CO 2 environment”
t0“rice”
Claim · model-written summary
CO2 response suggested biochemical resources shifted from RuBP carboxylation to regeneration.
- Taxon
- riceOryza sativat0
- Outcome
- reallocation of biochemical resources from RuBP carboxylation to RuBP regeneratione0
- Qualifier
- photosynthetic response at 5% CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The photosynthetic response at 5% CO 2 and the response of CO 2 assimilation (A) to internal CO 2 (C i ) suggest a reallocation of biochemical resources from RuBP carboxylation to RuBP regeneration”
t0“rice”
Claim · model-written summary
Elevated CO2 increased total plant biomass similarly in both cultivars.
- Taxon
- riceOryza sativat0
- Treatment
- elevated CO 2e0
- Outcome
- total plant biomasse0
- Direction
- Increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increases in total plant biomass at elevated CO 2 were approximately the same in both cultivars”
t0“rice”
Claim · model-written summary
Cultivars differed in root to shoot allocation under elevated CO2.
- Taxon
- riceOryza sativat0
- Outcome
- root/shoot ratioe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“differences in allocation patterns were noted in root/shoot ratio”
t0“rice”
Claim · model-written summary
IR‐36 harvest index rose significantly at elevated CO2.
- Taxon
- riceOryza sativat0
- Material
- IR‐36e0
- Treatment
- elevated CO 2e0
- Outcome
- harvest indexe0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at an elevated CO 2 environment with a significant increase in harvest index for IR‐36”
t0“rice”
Claim · model-written summary
Fujiyama‐5 did not show a significant harvest index increase at elevated CO2.
- Taxon
- riceOryza sativat0
- Material
- Fujiyama‐5e0
- Treatment
- elevated CO 2e1
- Outcome
- harvest indexe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant increase in harvest index for IR‐36 but not for Fujiyama‐5”
e1“at an elevated CO 2 environment”
t0“rice”
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