Abstract
Abstract Rising atmospheric CO 2 concentrations stimulate photosynthesis and productivity of C3 plants such as rice ( Oryza sativa L.), a phenomenon known as the CO 2 fertilization effect (CFE). Previous studies have shown that a greater sink capacity (e.g. grain number, or grain size) enhances the CFE on rice yield and that cytokinin is involved in the sink capacity; however, the direct involvement of this phytohormone in the CFE remains unclear. In this study, we tested whether exogenous application of kinetin improved the CFE of cultivars with different sink sizes (Koshihikari, japonica, with small sink; Takanari, indica with large sink ) using a free‐air CO 2 enrichment experiment on a rice paddy. We hypothesized that kinetin increases the sink size and thereby enhances the CFE, particularly for the cultivar with a smaller sink. Elevated CO 2 (200 µmol/mol above ambient concentration) increased grain yield by 11.4%, averaged across two cultivars. Kinetin significantly improved the CFE in Takanari from 11.2% to 19.2%, but not in Koshihikari. The enhancement of the CFE by kinetin in Takanari appeared through the increased sink size resulting from a greater panicle density. In contrast, kinetin did not increase panicle density or sink size in Koshihikari and failed to enhance the CFE. We therefore conclude that sink size improves CFE on rice yield, and that kinetin could increase sink size, but the effect is cultivar dependent.
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Claims 5
Claim · model-written summary
Elevated CO2 increased rice grain yield by 11.4% across two cultivars.
- Taxon
- rice
Oryza sativat0 - Treatment
- Elevated CO 2 (200 µmol/mol above ambient concentration)e0
- Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 11.4%e0
- Comparator
- ambient concentratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO 2 (200 µmol/mol above ambient concentration) increased grain yield by 11.4%, averaged across two cultivars”
t0“rice”
Claim · model-written summary
Kinetin improved the CO2 fertilization effect in Takanari from 11.2% to 19.2%.
- Taxon
- riceOryza sativat0
- Material
- Takanarie0
- Treatment
- Kinetine0
- Outcome
- CFEe0
- Direction
- improvede0
- Value
- 11.2% to 19.2%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Kinetin significantly improved the CFE in Takanari from 11.2% to 19.2%, but not in Koshihikari”
t0“rice”
Claim · model-written summary
Kinetin did not improve the CO2 fertilization effect in Koshihikari.
- Taxon
- riceOryza sativat0
- Material
- Koshihikarie0
- Treatment
- Kinetine0
- Outcome
- CFEe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Kinetin significantly improved the CFE in Takanari from 11.2% to 19.2%, but not in Koshihikari”
t0“rice”
Claim · model-written summary
In Takanari, kinetin enhanced the CO2 fertilization effect through greater panicle density and sink size.
- Taxon
- riceOryza sativat0
- Material
- Takanarie0
- Treatment
- kinetine0
- Outcome
- enhancement of the CFEe0
- Qualifier
- increased sink size resulting from a greater panicle densitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The enhancement of the CFE by kinetin in Takanari appeared through the increased sink size resulting from a greater panicle density”
t0“rice”
Claim · model-written summary
Kinetin did not increase panicle density or sink size in Koshihikari.
- Taxon
- riceOryza sativat0
- Material
- Koshihikarie0
- Treatment
- kinetine0
- Outcome
- panicle density or sink sizee0
- Direction
- did not increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“kinetin did not increase panicle density or sink size in Koshihikari”
t0“rice”
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