Abstract
During the last ice age, CO2 concentration ([CO2]) was 180-200 micromol/mol compared with the modern value of 380 micromol/mol, and global temperatures were approximately 8 degrees C cooler. Relatively little is known about the responses of C3 and C4 species to long-term exposure to glacial conditions. Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 micromol/mol CO2 with current (30/24 degrees C) and glacial (22/16 degrees C) temperatures for 22 d. Overall, the C4 species exhibited a large growth advantage over the C3 species at low [CO2]. However, this advantage was reduced at low temperature, where the C4 species produced 5 x the total mass of the C3 species versus 14 x at the high temperature. This difference was due to a reduction in C4 growth at low temperature, since the C3 species exhibited similar growth between temperatures. Physiological differences between temperatures were not detected for either species, although photorespiration/net photosynthesis was reduced in the C3 species grown at low temperature, suggesting evidence of improved carbon balance at this treatment. This system suggests that C4 species had a growth advantage over C3 species during low [CO2] of the last ice age, although concurrent reductions in temperatures may have reduced this advantage.
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Claims 8
Claim · model-written summary
At low CO2 the C4 species Amaranthus retroflexus showed a large growth advantage over the C3 species.
- Taxon
- Amaranthus retroflexus L. (C4)
Amaranthus retroflexuse0 - Treatment
- 200 micromol/mol CO2e0
- Outcome
- growth advantagee1
- Direction
- advantagee1
- Comparator
- C3 speciese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 micromol/mol CO2 with current (30/24 degrees C) and glacial (22/16 degrees C) temperatures for 22 d”
e1“Overall, the C4 species exhibited a large growth advantage over the C3 species at low [CO2]”
Claim · model-written summary
At low temperature the C4 species produced 5 times the total mass of the C3 species.
Verbatim
e2“this advantage was reduced at low temperature, where the C4 species produced 5 x the total mass of the C3 species versus 14 x at the high temperature”
Claim · model-written summary
At high temperature the C4 species produced 14 times the total mass of the C3 species.
Verbatim
e2“this advantage was reduced at low temperature, where the C4 species produced 5 x the total mass of the C3 species versus 14 x at the high temperature”
Claim · model-written summary
The growth advantage of the C4 species over the C3 species was reduced at low temperature compared with high temperature.
Verbatim
e2“this advantage was reduced at low temperature, where the C4 species produced 5 x the total mass of the C3 species versus 14 x at the high temperature”
Claim · model-written summary
The C3 species Abutilon theophrasti showed similar growth at glacial and current temperatures.
- Taxon
- Abutilon theophrasti Medik. (C3)
Abutilon theophrastie0 - Treatment
- glacial (22/16 degrees C) temperaturese0
- Outcome
- growthe3
- Direction
- similare3
- Comparator
- current (30/24 degrees C)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 micromol/mol CO2 with current (30/24 degrees C) and glacial (22/16 degrees C) temperatures for 22 d”
e3“the C3 species exhibited similar growth between temperatures”
Claim · model-written summary
The reduction in the C4 growth advantage at low temperature was due to a reduction in C4 growth.
- Taxon
- Amaranthus retroflexus L. (C4)Amaranthus retroflexuse0
- Treatment
- low temperaturee6
- Outcome
- C4 growthe6
- Direction
- reductione6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 micromol/mol CO2 with current (30/24 degrees C) and glacial (22/16 degrees C) temperatures for 22 d”
e6“due to a reduction in C4 growth at low temperature”
Claim · model-written summary
Physiological differences between glacial and current temperatures were not detected for either species.
- Taxon
- Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4)Abutilon theophrastiAmaranthus retroflexuse0
- Treatment
- glacial (22/16 degrees C) temperaturese0
- Outcome
- Physiological differencese4
- Direction
- not detectede4
- Comparator
- current (30/24 degrees C)e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 micromol/mol CO2 with current (30/24 degrees C) and glacial (22/16 degrees C) temperatures for 22 d”
e4“Physiological differences between temperatures were not detected for either species”
Claim · model-written summary
Photorespiration/net photosynthesis was reduced in the C3 species Abutilon theophrasti at low temperature, suggesting improved carbon balance.
- Taxon
- Abutilon theophrasti Medik. (C3)Abutilon theophrastie0
- Treatment
- low temperaturee5
- Outcome
- photorespiration/net photosynthesise5
- Direction
- reducede5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Here Abutilon theophrasti Medik. (C3) and Amaranthus retroflexus L. (C4) were grown at 200 micromol/mol CO2 with current (30/24 degrees C) and glacial (22/16 degrees C) temperatures for 22 d”
e5“photorespiration/net photosynthesis was reduced in the C3 species grown at low temperature”
The same questions in other papers
cold · physiology: photosynthesis · Abutilon theophrasti (velvetleaf)Positive and negative results
1 in the opposite direction
- negative
co2 · growth · Amaranthus retroflexus (redroot amaranth)Positive and negative results
1 paper in the same direction as this paper · 5 in the opposite direction
- no effect
- no effect
- no effect
3 papers more in this group
See all 7 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.