Abstract
Gas exchange rates were measured during podfill on leaflets of soybean [ Glycine max (L.) Merr. ‘Bragg’] plants grown in 330 (ambient) and 660 (high) μmol CO 2 −1 environments in outdoor growth chambers and rooted in a reconstituted profile of Arredondo fine sand (loamy, siliceous, hyperthermic Grossarenic Plaleudult). Carbon exchange rates (CER), transpiration rates (TR), leaf resistance ( r L ) and leaf temperature ( T L ) measured to investigate their diurnal changes. These parameters were also measured during midday periods at various CO 2 concentrations (90‐990 μmol CO 2 mol −1 ) to study the effects of adaptation to ambient and high CO 2 , environments on the subsequent response to CO 2 levels. The primary objective was to determine CO 2 effects on leaf water use and water‐use efficiency, an important question as global CO 2 continues to rise. Diurnal TR of leaflets grown and measured at high CO 2 levels was not different from TR of leaflets grown and measured at ambient CO 2 . Leaf temperature was approximately 1.5°C higher for the leaflets at the high CO 2 concentration; also, r L was higher throughout the day on these leaflets than r L of those at ambient CO 2 levels. Water use efficiency (WUE = CER/TRf) or leaflets at high CO 2 was about twice the WUE of leaflets grown and measured at ambient CO 2 . Transpiration rates of leaflets adapted to ambient or high CO 2 concentrations were not significantly affected by short‐term CO 2 changes. However, regardless of CO 2 level of adaptation, T L and r L increased as CO 2 increased. It was concluded that: (i) TR of the high CO 2 leaflets was similar that of ambient CO 2 leaflets because the increases in r L caused by high CO 2 were partially offset by increases in vapor pressure gradient between leaf‐to‐air caused by increased T L ; (ii) Leaves adapted to high CO 2 had higher WUE than leaves adapted to ambient CO 2 , mainly because of a two‐fold increase in CER.
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Claims 9
Claim · model-written summary
High CO2 grown and measured leaflets had similar diurnal transpiration to ambient CO2 leaflets.
- Taxon
- Soybean
Glycine maxt0 - Treatment
- high CO 2 levelse0
- Outcome
- Diurnal TRe0
- Direction
- not differente0
- Comparator
- ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Diurnal TR of leaflets grown and measured at high CO 2 levels was not different from TR of leaflets grown and measured at ambient CO 2 .”
t0“Soybean Leaves”
Claim · model-written summary
High CO2 leaflets were about 1.5°C warmer.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- high CO 2 concentratione0
- Outcome
- Leaf temperaturee0
- Direction
- highere0
- Value
- 1.5°Ce0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf temperature was approximately 1.5°C higher for the leaflets at the high CO 2 concentration”
t0“Soybean Leaves”
Claim · model-written summary
Leaf resistance was higher throughout the day under high CO2.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- these leafletse0
- Outcome
- r Le0
- Direction
- highere0
- Comparator
- ambient CO 2 levelse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“r L was higher throughout the day on these leaflets than r L of those at ambient CO 2 levels”
t0“Soybean Leaves”
Claim · model-written summary
High CO2 leaflets had about twice the water use efficiency of ambient CO2 leaflets.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- high CO 2e0
- Outcome
- Water use efficiencye0
- Direction
- twicee0
- Value
- about twicee0
- Comparator
- ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Water use efficiency (WUE = CER/TRf) or leaflets at high CO 2 was about twice the WUE of leaflets grown and measured at ambient CO 2 .”
t0“Soybean Leaves”
Claim · model-written summary
Short term CO2 changes did not significantly affect transpiration in either adaptation group.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- short‐term CO 2 changese0
- Outcome
- Transpiration ratese0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transpiration rates of leaflets adapted to ambient or high CO 2 concentrations were not significantly affected by short‐term CO 2 changes.”
t0“Soybean Leaves”
Claim · model-written summary
Leaf temperature increased with CO2 regardless of adaptation.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- CO 2e0
- Outcome
- T Le0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“regardless of CO 2 level of adaptation, T L and r L increased as CO 2 increased”
t0“Soybean Leaves”
Claim · model-written summary
Leaf resistance increased with CO2 regardless of adaptation.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- CO 2e0
- Outcome
- r Le0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“regardless of CO 2 level of adaptation, T L and r L increased as CO 2 increased”
t0“Soybean Leaves”
Claim · model-written summary
The authors attribute similar transpiration to a vapor pressure gradient offsetting leaf resistance.
- Taxon
- SoybeanGlycine maxt0
- Outcome
- TRe0
- Direction
- similare0
- Qualifier
- increases in vapor pressure gradient between leaf‐to‐aire0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“TR of the high CO 2 leaflets was similar that of ambient CO 2 leaflets because the increases in r L caused by high CO 2 were partially offset by increases in vapor pressure gradient between leaf‐to‐air caused by increased T L”
t0“Soybean Leaves”
Claim · model-written summary
The authors attribute higher water use efficiency mainly to a twofold increase in carbon exchange rate.
- Taxon
- SoybeanGlycine maxt0
- Treatment
- high CO 2e0
- Outcome
- WUEe0
- Direction
- highere0
- Qualifier
- two‐fold increase in CERe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaves adapted to high CO 2 had higher WUE than leaves adapted to ambient CO 2 , mainly because of a two‐fold increase in CER”
t0“Soybean Leaves”
The same questions in other papers
co2 · physiology: gas exchange · Glycine max (soybean)Positive and negative results
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See all 11 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.