Abstract
Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species, were grown in pots in monoculture and mixed culture (2 C3 : 1 C4 and 1 C3:2 C4) at two ambient partial pressures of CO2 (320 and 640 μbar), two photosynthetic photon flux densities (PPFDs) (daily maximum 2000 and 500 �mol m-2 s-1) and two levels of nitrogen nutrition (12 mM and 2 mM NO3-). Growth of shoots of both components in mixed culture was measured by physical separation, and the proportions of root biomass due to each component were calculated from δ13C value of total root biomass. In air (320 μbar CO2) at high PPFD and with high root zone-N, the shoot biomass of C3 and C4 components at the first harvest (28 days) was in proportion to the sowing ratio. However, by the second harvest (36 days) the C4 component predominated in both mixtures. Under the same conditions, but with low PPFD, C3 plants predominated at the first harvest but C4 plants had over- taken them by the time of the second harvest. Elevated atmospheric CO2 (640 μbar) stimulated shoot growth of Triticum in 15 of 16 treatment combinations and the stimulation was greatest in plants provided with low NO3-. Root growth of the C3 plants was generally stimulated by elevated CO2, but was only occasionally sensitive to the presence of C4 plants in mixed culture. However, growth of the C4 plants was often sensitive to the presence of C3 plants in mixed culture. In mixed cultures, elevated CO2 plants stimulated growth of C4 plants at high PPFD, high-N and in all low-N treatments but this was insufficient to offset a marked decline in shoot growth with increasing proportion of C3 plants in mixed cultures. The unexpected stimulation of growth of C4 plants by elevated CO2 was correlated with more negative δ13C values of C4 root biomass, suggesting a partial failure of the CO2 concentrating mechanism of C4 photosynthesis in Echinochloa under low-N. These experiments show that for these species nitrogen was more important than light or elevated pCO2 in determining the extent of competitive interactions in mixed culture.
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Claims 13
Claim · model-written summary
At the first harvest under high light and nitrogen, shoot biomass of both components matched sowing ratio.
- Taxon
- Triticum aestivum
Triticum aestivumt0 - Outcome
- shoot biomasse0
- Qualifier
- first harvest (28 days)e0
- Comparator
- sowing ratioe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the shoot biomass of C3 and C4 components at the first harvest (28 days) was in proportion to the sowing ratio.”
t0“Triticum aestivum”
Claim · model-written summary
At the second harvest under high light and nitrogen, Japanese millet predominated in both mixtures.
- Taxon
- Japanese millet
Echinochloa frumentaceae1 - Interactor
- WheatTriticum aestivume1other
- Outcome
- C4 component predominatede0
- Qualifier
- second harvest (36 days)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“by the second harvest (36 days) the C4 component predominated in both mixtures.”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
Claim · model-written summary
Under low light, wheat predominated at the first harvest.
- Taxon
- WheatTriticum aestivume1
- Interactor
- Japanese milletEchinochloa frumentaceae1other
- Outcome
- C3 plants predominatede0
- Qualifier
- low PPFDe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with low PPFD, C3 plants predominated at the first harvest”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
Claim · model-written summary
Under low light, Japanese millet overtook wheat by the second harvest.
- Taxon
- Japanese milletEchinochloa frumentaceae1
- Interactor
- WheatTriticum aestivume1other
- Outcome
- C4 plants had over- taken theme0
- Qualifier
- second harveste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“C4 plants had over- taken them by the time of the second harvest.”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
Claim · model-written summary
Elevated carbon dioxide stimulated wheat shoot growth in 15 of 16 treatment combinations.
- Treatment
- Elevated atmospheric CO2 (640 μbar)e0
- Outcome
- shoot growthe0
- Direction
- stimulatede0
- Value
- 15 of 16 treatment combinationse0
- Comparator
- 320e1
TriticumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated atmospheric CO2 (640 μbar) stimulated shoot growth of Triticum in 15 of 16 treatment combinations”
e1“two ambient partial pressures of CO2 (320 and 640 μbar)”
Claim · model-written summary
Carbon dioxide stimulation of wheat shoot growth was greatest under low nitrate.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the stimulation was greatest in plants provided with low NO3-”
e1“shoot growth of Triticum”
Claim · model-written summary
Elevated carbon dioxide generally stimulated wheat root growth.
- Taxon
- WheatTriticum aestivume1
- Treatment
- elevated CO2e0
- Outcome
- Root growthe0
- Direction
- stimulatede0
- Comparator
- 320e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root growth of the C3 plants was generally stimulated by elevated CO2”
e1“Wheat (Triticum aestivum L.), a C3 species”
e2“two ambient partial pressures of CO2 (320 and 640 μbar)”
Claim · model-written summary
Wheat root growth was only occasionally sensitive to Japanese millet in mixed culture.
- Taxon
- WheatTriticum aestivume1
- Interactor
- Japanese milletEchinochloa frumentaceae1other
- Outcome
- Root growthe2
- Qualifier
- only occasionallye0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“was only occasionally sensitive to the presence of C4 plants in mixed culture.”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
e2“Root growth of the C3 plants”
Claim · model-written summary
Japanese millet growth was often sensitive to wheat in mixed culture.
- Taxon
- Japanese milletEchinochloa frumentaceae1
- Interactor
- WheatTriticum aestivume1other
- Outcome
- growth of the C4 plantse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“growth of the C4 plants was often sensitive to the presence of C3 plants in mixed culture.”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
Claim · model-written summary
Elevated carbon dioxide stimulated millet growth at high light and nitrogen and in all low nitrogen treatments.
- Taxon
- Japanese milletEchinochloa frumentaceae1
- Treatment
- elevated CO2e0
- Interactor
- WheatTriticum aestivume1other
- Outcome
- growth of C4 plantse0
- Direction
- stimulatede0
- Qualifier
- high PPFD, high-N and in all low-N treatmentse0
- Comparator
- 320e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO2 plants stimulated growth of C4 plants at high PPFD, high-N and in all low-N treatments”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
e2“two ambient partial pressures of CO2 (320 and 640 μbar)”
Claim · model-written summary
Increasing the wheat proportion markedly reduced millet shoot growth in mixed culture.
- Taxon
- Japanese milletEchinochloa frumentaceae1
- Treatment
- increasing proportion of C3 plantse0
- Interactor
- WheatTriticum aestivume1other
- Outcome
- shoot growthe0
- Direction
- declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“marked decline in shoot growth with increasing proportion of C3 plants in mixed cultures.”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
Claim · model-written summary
Millet growth stimulation by carbon dioxide correlated with more negative root carbon isotope values.
- Taxon
- Japanese milletEchinochloa frumentaceae1
- Treatment
- elevated CO2e0
- Outcome
- growth of C4 plantse0
- Direction
- stimulatione0
- Qualifier
- more negative δ13C values of C4 root biomasse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stimulation of growth of C4 plants by elevated CO2 was correlated with more negative δ13C values of C4 root biomass”
e1“Japanese millet (Echinochloa frumentacea Link)”
Claim · model-written summary
Nitrogen was more important than light or carbon dioxide in determining mixed culture competition.
- Taxon
- WheatTriticum aestivume1
- Interactor
- Japanese milletEchinochloa frumentaceae1other
- Outcome
- extent of competitive interactions in mixed culturee0
- Comparator
- light or elevated pCO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrogen was more important than light or elevated pCO2 in determining the extent of competitive interactions in mixed culture.”
e1“Wheat (Triticum aestivum L.), a C3 species, and Japanese millet (Echinochloa frumentacea Link), a C4 species”
The same questions in other papers
co2 · growth · Triticum aestivum (wheat)Positive and negative results
123 papers in the same direction as this paper · 20 in the opposite direction · 1 reporting no difference from an alternative
- positive
- positive
- no effect
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