Abstract
Abstract Increasing atmospheric CO 2 is recognized as a major aspect of global climate change that would have a significant impact on the productivity of major agricultural crops. Two field experiments were done, with the objective of quantifying the response of a short‐duration rice ( Oryza sativa ) variety (BG‐300) to elevated atmospheric carbon dioxide, in the low elevation, subhumid zone of Sri Lanka. The experiment contained three treatments. In the elevated CO 2 treatment, rice was grown at a CO 2 concentration of 570 µmol/mol within open top chambers (OTC s). The ambient CO 2 treatment included crops grown within OTC s, but maintained at the ambient CO 2 concentration of 370 µmol/mol. The third treatment was a crop grown in the open field under ambient CO 2 concentration. Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments in the maha (January – March 2001) and yala (May – August, 2001) seasons. Significant increases in total biomass at harvest (23 % and 39 %, respectively, in maha and yala ) were more responsible for the above yield increases than the slight increases in the harvest index (4 % and 2 %). Yields of the ambient and open field treatments did not differ significantly. Among the yield components, the number of panicles per hill was significantly higher in the elevated treatment and showed significant positive correlations with grain yield in both seasons. In addition, grain yield showed significant positive correlations with the percentage of filled grains in maha and the number of grains per panicle in yala . Significant increases in the number of tillers per hill under elevated CO 2 were responsible for its greater leaf area index and the greater numbers of panicles per hill. Crops under elevated CO 2 accumulated biomass faster than those grown under ambient CO 2 during the vegetative and grain‐filling stages. The results of this study demonstrate that elevated CO 2 causes significant yield increases in rice, even when it is grown in warm, subhumid tropical climates.
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Claims 15
Claim · model-written summary
Elevated CO2 increased rice grain yield by 24% in maha relative to ambient treatments.
- Taxon
- rice
Oryza sativae0 - Treatment
- elevated CO 2e0
- Outcome
- Grain yieldse0
- Direction
- greatere0
- Value
- 24 %e0
- Qualifier
- maha (January – March 2001)e0
- Comparator
- ambient treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments in the maha (January – March 2001) and yala (May – August, 2001) seasons.”
Claim · model-written summary
Elevated CO2 increased rice grain yield by 39% in yala relative to ambient treatments.
- Taxon
- riceOryza sativae0
- Treatment
- elevated CO 2e0
- Outcome
- Grain yieldse0
- Direction
- greatere0
- Value
- 39 %e0
- Qualifier
- yala (May – August, 2001)e0
- Comparator
- ambient treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments in the maha (January – March 2001) and yala (May – August, 2001) seasons.”
Claim · model-written summary
Total biomass at harvest increased significantly by 23% in maha.
- Taxon
- riceOryza sativae1
- Treatment
- elevated CO 2e1
- Outcome
- total biomass at harveste0
- Direction
- increasese0
- Value
- 23 %e0
- Qualifier
- mahae0
- Comparator
- ambient treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in total biomass at harvest (23 % and 39 %, respectively, in maha and yala ) were more responsible for the above yield increases than the slight increases in the harvest index (4 % and 2 %).”
e1“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments”
Claim · model-written summary
Total biomass at harvest increased significantly by 39% in yala.
- Taxon
- riceOryza sativae1
- Treatment
- elevated CO 2e1
- Outcome
- total biomass at harveste0
- Direction
- increasese0
- Value
- 39 %e0
- Qualifier
- yalae0
- Comparator
- ambient treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in total biomass at harvest (23 % and 39 %, respectively, in maha and yala ) were more responsible for the above yield increases than the slight increases in the harvest index (4 % and 2 %).”
e1“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments”
Claim · model-written summary
Harvest index increased slightly by 4% in maha.
- Taxon
- riceOryza sativae1
- Treatment
- elevated CO 2e1
- Outcome
- harvest indexe0
- Direction
- increasese0
- Value
- 4 %e0
- Qualifier
- mahae0
- Comparator
- ambient treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in total biomass at harvest (23 % and 39 %, respectively, in maha and yala ) were more responsible for the above yield increases than the slight increases in the harvest index (4 % and 2 %).”
e1“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments”
Claim · model-written summary
Harvest index increased slightly by 2% in yala.
- Taxon
- riceOryza sativae1
- Treatment
- elevated CO 2e1
- Outcome
- harvest indexe0
- Direction
- increasese0
- Value
- 2 %e0
- Qualifier
- yalae0
- Comparator
- ambient treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in total biomass at harvest (23 % and 39 %, respectively, in maha and yala ) were more responsible for the above yield increases than the slight increases in the harvest index (4 % and 2 %).”
e1“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments”
Claim · model-written summary
Biomass increases contributed more to rice yield increases than harvest-index increases.
- Taxon
- RiceOryza sativat0
- Outcome
- yield increasese0
- Qualifier
- increases in total biomass at harveste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in total biomass at harvest (23 % and 39 %, respectively, in maha and yala ) were more responsible for the above yield increases than the slight increases in the harvest index (4 % and 2 %).”
t0“Rice”
Claim · model-written summary
Rice yields did not differ significantly between ambient chamber and open-field treatments.
- Taxon
- RiceOryza sativat0
- Treatment
- ambiente0
- Outcome
- Yieldse0
- Direction
- did not differ significantlye0
- Comparator
- open field treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yields of the ambient and open field treatments did not differ significantly.”
t0“Rice”
Claim · model-written summary
Panicles per hill were significantly higher under elevated CO2.
- Taxon
- riceOryza sativae1
- Treatment
- elevated CO 2e1
- Outcome
- number of panicles per hille0
- Direction
- highere0
- Comparator
- ambient treatmentse1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Among the yield components, the number of panicles per hill was significantly higher in the elevated treatment”
e1“Grain yields of rice crops grown under elevated CO 2 were 24 % and 39 % greater than the respective ambient treatments”
Claim · model-written summary
Panicle number per hill correlated positively and significantly with grain yield in both seasons.
- Taxon
- RiceOryza sativat0
- Outcome
- grain yielde0
- Direction
- positive correlationse0
- Qualifier
- both seasonse0
- Comparator
- number of panicles per hille0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the number of panicles per hill was significantly higher in the elevated treatment and showed significant positive correlations with grain yield in both seasons.”
t0“Rice”
Claim · model-written summary
Grain yield correlated significantly and positively with filled-grain percentage in maha.
- Taxon
- RiceOryza sativat0
- Outcome
- grain yielde0
- Direction
- positive correlationse0
- Qualifier
- mahae0
- Comparator
- percentage of filled grainse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“grain yield showed significant positive correlations with the percentage of filled grains in maha and the number of grains per panicle in yala”
t0“Rice”
Claim · model-written summary
Grain yield correlated significantly and positively with grains per panicle in yala.
- Taxon
- RiceOryza sativat0
- Outcome
- grain yielde0
- Direction
- positive correlationse0
- Qualifier
- yalae0
- Comparator
- number of grains per paniclee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“grain yield showed significant positive correlations with the percentage of filled grains in maha and the number of grains per panicle in yala”
t0“Rice”
Claim · model-written summary
Elevated CO2 significantly increased tillers per hill.
- Taxon
- RiceOryza sativat0
- Treatment
- elevated CO 2e0
- Outcome
- number of tillers per hille0
- Direction
- increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in the number of tillers per hill under elevated CO 2 were responsible for its greater leaf area index and the greater numbers of panicles per hill.”
t0“Rice”
Claim · model-written summary
Increased tillering under elevated CO2 explained greater leaf area index and panicle numbers.
- Taxon
- RiceOryza sativat0
- Treatment
- elevated CO 2e0
- Outcome
- greater leaf area index and the greater numbers of panicles per hille0
- Qualifier
- increases in the number of tillers per hille0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Significant increases in the number of tillers per hill under elevated CO 2 were responsible for its greater leaf area index and the greater numbers of panicles per hill.”
t0“Rice”
Claim · model-written summary
Elevated CO2 accelerated biomass accumulation during vegetative and grain-filling stages relative to ambient CO2.
- Taxon
- RiceOryza sativat0
- Organ / stage
- vegetative and grain‐filling stagese0
- Treatment
- elevated CO 2e0
- Outcome
- biomasse0
- Direction
- fastere0
- Comparator
- ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Crops under elevated CO 2 accumulated biomass faster than those grown under ambient CO 2 during the vegetative and grain‐filling stages.”
t0“Rice”
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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.