Abstract
Elevated levels of atmospheric CO2 (eCO2) promote rice growth and increase methane (CH4) emissions from rice paddies, because increased input of plant photosynthate to soil stimulates methanogenic archae. However, temporal trends in the effects of eCO2 on rice growth and CH4 emissions are still unclear. To investigate changes in the effects of eCO2 over time, we conducted a two-season pot experiment in a walk-in growth chamber. Positive effects of eCO2 on rice leaf photosynthetic rate, biomass, and grain yield were similar between growing seasons. However, the effects of eCO2 on CH4 emissions decreased over time. Elevated CO2 increased CH4 emissions by 48%–101% in the first growing season, but only by 28%–30% in the second growing season. We also identified the microbial process underlying the acclimation of CH4 emissions to atmospheric CO2 enrichment: eCO2 stimulated the abundance of methanotrophs more strongly in soils that had been previously exposed to eCO2 than in soils that had not been. These results emphasize the need for long-term eCO2 experiments for accurate predictions of terrestrial feedbacks.
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Claims 7
Claim · model-written summary
Elevated CO2 increased rice leaf photosynthetic rate similarly across growing seasons.
- Taxon
- rice
Oryza sativae0 - Treatment
- eCO2e0
- Outcome
- leaf photosynthetic ratee0
- Direction
- Positivee0
- Qualifier
- similar between growing seasonse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Positive effects of eCO2 on rice leaf photosynthetic rate, biomass, and grain yield were similar between growing seasons.”
Claim · model-written summary
Elevated CO2 increased rice biomass similarly across growing seasons.
- Taxon
- riceOryza sativae0
- Treatment
- eCO2e0
- Outcome
- biomasse0
- Direction
- Positivee0
- Qualifier
- similar between growing seasonse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Positive effects of eCO2 on rice leaf photosynthetic rate, biomass, and grain yield were similar between growing seasons.”
Claim · model-written summary
Elevated CO2 increased rice grain yield similarly across growing seasons.
- Taxon
- riceOryza sativae0
- Treatment
- eCO2e0
- Outcome
- grain yielde0
- Direction
- Positivee0
- Qualifier
- similar between growing seasonse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Positive effects of eCO2 on rice leaf photosynthetic rate, biomass, and grain yield were similar between growing seasons.”
Claim · model-written summary
The effect of elevated CO2 on methane emissions declined over time.
- Taxon
- riceOryza sativae1
- Treatment
- eCO2e0
- Outcome
- CH4 emissionse0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effects of eCO2 on CH4 emissions decreased over time.”
e1“rice growth and CH4 emissions”
Claim · model-written summary
Elevated CO2 raised methane emissions by 48%–101% in the first season.
- Taxon
- riceOryza sativae1
- Treatment
- Elevated CO2e0
- Outcome
- CH4 emissionse0
- Direction
- increasede0
- Value
- 48%–101%e0
- Qualifier
- first growing seasone0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO2 increased CH4 emissions by 48%–101% in the first growing season”
e1“rice growth and CH4 emissions”
Claim · model-written summary
Elevated CO2 raised methane emissions by 28%–30% in the second season.
- Taxon
- riceOryza sativae1
- Treatment
- Elevated CO2e0
- Outcome
- CH4 emissionse0
- Direction
- increasede0
- Value
- 28%–30%e0
- Qualifier
- second growing seasone0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO2 increased CH4 emissions by 48%–101% in the first growing season, but only by 28%–30% in the second growing season.”
e1“rice growth and CH4 emissions”
Claim · model-written summary
Elevated CO2 stimulated methanotroph abundance more strongly in previously exposed soils.
- Taxon
- riceOryza sativae1
- Treatment
- eCO2e0
- Interactor
- methanotrophse0other
- Outcome
- abundance of methanotrophse0
- Direction
- more stronglye0
- Comparator
- soils that had not beene0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“eCO2 stimulated the abundance of methanotrophs more strongly in soils that had been previously exposed to eCO2 than in soils that had not been.”
e1“rice growth and CH4 emissions”
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See all 159 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.