Abstract
A controlled growth chamber experiment was conducted to investigate the short-term water use and photosynthetic responses of 30-d-old carrot seedlings to the combined effects of CO2 concentration (50-1 050 µmol mol-1) and moisture deficits (-5, -30, -55, and -70 kPa). The photosynthetic response data was fitted to a non-rectangular hyperbola model. The estimated parameters were compared for effects of moisture deficit and elevated CO2 concentration (EC). The carboxylation efficiency (α) increased in response to mild moisture stress (-30 kPa) under EC when compared to the unstressed control. However, moderate (-55 kPa) and extreme (-70 kPa) moisture deficits reduced α under EC. Maximum net photosynthetic rate (P Nmax) did not differ between mild water deficit and unstressed controls under EC. Moderate and extreme moisture deficits reduced P Nmax by nearly 85 % compared to controls. Dark respiration rate (R D) showed no consistent response to moisture deficit. The CO2 compensation concentration (Γ) was 324 µmol mol-1 for -75 kPa and ranged 63-93 µmol mol-1 for other moisture regimes. Interaction between moisture deficit and EC was noticed for P N, ratio of intercellular and ambient CO2 concentration (C i/C a), stomatal conductance (g s ), and transpiration rate (E). P N was maximum and C i/C a was minimum at -30 kPa moisture deficit and at C a of 350 µmol mol-1. The g s and E showed an inverse relationship at all moisture deficit regimes and EC. Water use efficiency (WUE) increased with moisture deficit up to -55 kPa and declined thereafter. EC showed a positive influence towards sustaining P N and increasing WUE only under mild moisture stress, and no beneficial effects of EC were noticed at moderate or extreme moisture deficits.
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Claims 14
Claim · model-written summary
Mild moisture stress increased carrot carboxylation efficiency under elevated CO2.
- Taxon
- carrot
Daucus carotat0 - Treatment
- mild moisture stress (-30 kPa)e0
- Outcome
- carboxylation efficiency (α)e0
- Direction
- increasede0
- Qualifier
- under ECe0
- Comparator
- unstressed controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“The carboxylation efficiency (α) increased in response to mild moisture stress (-30 kPa) under EC when compared to the unstressed control”
Claim · model-written summary
Moderate and extreme moisture deficits reduced carrot carboxylation efficiency under elevated CO2.
- Taxon
- carrotDaucus carotat0
- Treatment
- moderate (-55 kPa) and extreme (-70 kPa) moisture deficitse0
- Outcome
- αe0
- Direction
- reducede0
- Qualifier
- under ECe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“moderate (-55 kPa) and extreme (-70 kPa) moisture deficits reduced α under EC”
Claim · model-written summary
Maximum net photosynthetic rate did not differ under mild water deficit versus unstressed controls at elevated CO2.
- Taxon
- carrotDaucus carotat0
- Treatment
- mild water deficite0
- Outcome
- Maximum net photosynthetic rate (P Nmax)e0
- Direction
- did not differe0
- Comparator
- unstressed controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“Maximum net photosynthetic rate (P Nmax) did not differ between mild water deficit and unstressed controls under EC”
Claim · model-written summary
Moderate and extreme moisture deficits reduced carrot maximum net photosynthetic rate by nearly 85% versus controls.
- Taxon
- carrotDaucus carotat0
- Treatment
- Moderate and extreme moisture deficitse0
- Outcome
- P Nmaxe0
- Direction
- reducede0
- Value
- nearly 85 %e0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“Moderate and extreme moisture deficits reduced P Nmax by nearly 85 % compared to controls”
Claim · model-written summary
Dark respiration rate showed no consistent response to moisture deficit.
- Taxon
- carrotDaucus carotat0
- Treatment
- moisture deficite0
- Outcome
- Dark respiration rate (R D)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“Dark respiration rate (R D) showed no consistent response to moisture deficit”
Claim · model-written summary
CO2 compensation concentration was 324 µmol mol-1 at -75 kPa and 63-93 µmol mol-1 under other moisture regimes.
- Taxon
- carrotDaucus carotat0
- Outcome
- CO2 compensation concentration (Γ)e0
- Value
- 324 µmol mol-1e0
- Qualifier
- -75 kPae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“The CO2 compensation concentration (Γ) was 324 µmol mol-1 for -75 kPa and ranged 63-93 µmol mol-1 for other moisture regimes”
Claim · model-written summary
Moisture deficit and elevated CO2 interacted for net photosynthesis, intercellular-to-ambient CO2 ratio, stomatal conductance and transpiration.
- Taxon
- carrotDaucus carotat0
- Treatment
- moisture deficit and ECe0
- Outcome
- P N, ratio of intercellular and ambient CO2 concentration (C i/C a), stomatal conductance (g s ), and transpiration rate (E)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“Interaction between moisture deficit and EC was noticed for P N, ratio of intercellular and ambient CO2 concentration (C i/C a), stomatal conductance (g s ), and transpiration rate (E)”
Claim · model-written summary
Net photosynthesis was maximal at -30 kPa moisture deficit and 350 µmol mol-1 ambient CO2.
- Taxon
- carrotDaucus carotat0
- Outcome
- P Ne0
- Direction
- maximume0
- Qualifier
- -30 kPa moisture deficit and at C a of 350 µmol mol-1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“P N was maximum and C i/C a was minimum at -30 kPa moisture deficit and at C a of 350 µmol mol-1”
Claim · model-written summary
Intercellular-to-ambient CO2 ratio was minimal at -30 kPa moisture deficit and 350 µmol mol-1 ambient CO2.
- Taxon
- carrotDaucus carotat0
- Outcome
- C i/C ae0
- Direction
- minimume0
- Qualifier
- -30 kPa moisture deficit and at C a of 350 µmol mol-1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“P N was maximum and C i/C a was minimum at -30 kPa moisture deficit and at C a of 350 µmol mol-1”
Claim · model-written summary
Stomatal conductance and transpiration had an inverse relationship across moisture deficits and elevated CO2.
- Taxon
- carrotDaucus carotat0
- Treatment
- moisture deficit regimes and ECe0
- Outcome
- g s and Ee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“The g s and E showed an inverse relationship at all moisture deficit regimes and EC”
Claim · model-written summary
Water use efficiency increased with moisture deficit up to -55 kPa.
- Taxon
- carrotDaucus carotat0
- Treatment
- moisture deficite0
- Outcome
- Water use efficiency (WUE)e0
- Direction
- increasede0
- Qualifier
- up to -55 kPae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“Water use efficiency (WUE) increased with moisture deficit up to -55 kPa and declined thereafter”
Claim · model-written summary
Water use efficiency declined beyond -55 kPa moisture deficit.
- Taxon
- carrotDaucus carotat0
- Treatment
- moisture deficite0
- Outcome
- Water use efficiency (WUE)e0
- Direction
- declinede0
- Qualifier
- thereaftere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“Water use efficiency (WUE) increased with moisture deficit up to -55 kPa and declined thereafter”
Claim · model-written summary
Elevated CO2 sustained net photosynthesis only under mild moisture stress, with no beneficial effect at moderate or extreme deficits.
- Taxon
- carrotDaucus carotat0
- Treatment
- ECe0
- Outcome
- P Ne0
- Direction
- sustaininge0
- Qualifier
- only under mild moisture stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“EC showed a positive influence towards sustaining P N and increasing WUE only under mild moisture stress, and no beneficial effects of EC were noticed at moderate or extreme moisture deficits”
Claim · model-written summary
Elevated CO2 increased water use efficiency only under mild moisture stress.
- Taxon
- carrotDaucus carotat0
- Treatment
- ECe0
- Outcome
- WUEe0
- Direction
- increasinge0
- Qualifier
- only under mild moisture stresse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“carrot leaves”
e0“EC showed a positive influence towards sustaining P N and increasing WUE only under mild moisture stress, and no beneficial effects of EC were noticed at moderate or extreme moisture deficits”
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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.