Abstract
Effects of elevated root-zone (RZ) CO2 concentration (RZ [CO2]) and RZ temperature (RZT) on photosynthesis, productivity, nitrate (NO3 -), total reduced nitrogen (TRN), total leaf soluble and Rubisco proteins were studied in aeroponically grown lettuce plants in a tropical greenhouse. Three weeks after transplanting, four different RZ [CO2] concentrations (ambient, 360 ppm, and elevated concentrations of 2,000; 10,000; and 50,000 ppm) were imposed on plants at 20°C-RZT or ambient(A)-RZT (24-38°C). Elevated RZ [CO2] resulted in significantly higher light-saturated net photosynthetic rate, but lower light-saturated stomatal conductance. Higher elevated RZ [CO2] also protected plants from both chronic and dynamic photoinhibition (measured by chlorophyll fluorescence Fv/Fm ratio) and reduced leaf water loss. Under each RZ [CO2], all these variables were significantly higher in 20°C-RZT plants than in A-RZT plants. All plants accumulated more biomass at elevated RZ [CO2] than at ambient RZ [CO2]. Greater increases of biomass in roots than in shoots were manifested by lower shoot/root ratios at elevated RZ [CO2]. Although the total biomass was higher at 20°C-RZT, the increase in biomass under elevated RZ [CO2] was greater at A-RZT. Shoot NO3 - and TRN concentrations, total leaf soluble and Rubisco protein concentrations were higher in all elevated RZ [CO2] plants than in plants under ambient RZ [CO2] at both RZTs. Under each RZ [CO2], total leaf soluble and Rubisco protein concentrations were significantly higher at 20°C-RZT than at A-RZT. Our results demonstrated that increased P Nmax and productivity under elevated [CO2] was partially due to the alleviation of midday water loss, both dynamic and chronic photoinhibition as well as higher turnover of Calvin cycle with higher Rubisco proteins.
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Claims 13
Claim · model-written summary
Elevated root-zone CO2 increased light-saturated photosynthesis significantly.
- Taxon
- lettuce
Lactuca sativat0 - Treatment
- Elevated RZ [CO2]e0
- Outcome
- light-saturated net photosynthetic ratee0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated RZ [CO2] resulted in significantly higher light-saturated net photosynthetic rate, but lower light-saturated stomatal conductance”
t0“lettuce”
Claim · model-written summary
Elevated root-zone CO2 lowered light-saturated stomatal conductance.
- Taxon
- lettuceLactuca sativat0
- Treatment
- Elevated RZ [CO2]e0
- Outcome
- light-saturated stomatal conductancee0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated RZ [CO2] resulted in significantly higher light-saturated net photosynthetic rate, but lower light-saturated stomatal conductance”
t0“lettuce”
Claim · model-written summary
Higher root-zone CO2 protected lettuce from chronic and dynamic photoinhibition.
- Taxon
- lettuceLactuca sativat0
- Treatment
- Higher elevated RZ [CO2]e0
- Outcome
- chronic and dynamic photoinhibitione0
- Direction
- protectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher elevated RZ [CO2] also protected plants from both chronic and dynamic photoinhibition (measured by chlorophyll fluorescence Fv/Fm ratio)”
t0“lettuce”
Claim · model-written summary
Higher root-zone CO2 reduced leaf water loss.
- Taxon
- lettuceLactuca sativat0
- Treatment
- Higher elevated RZ [CO2]e0
- Outcome
- leaf water losse0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Higher elevated RZ [CO2] also protected plants from both chronic and dynamic photoinhibition (measured by chlorophyll fluorescence Fv/Fm ratio) and reduced leaf water loss”
t0“lettuce”
Claim · model-written summary
Across CO2 levels, the preceding physiological variables were higher at 20°C than ambient root-zone temperature.
- Taxon
- lettuceLactuca sativat0
- Treatment
- 20°C-RZTe0
- Outcome
- all these variablese0
- Direction
- highere0
- Comparator
- A-RZTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under each RZ [CO2], all these variables were significantly higher in 20°C-RZT plants than in A-RZT plants”
t0“lettuce”
Claim · model-written summary
All plants accumulated more biomass at elevated than ambient root-zone CO2.
- Taxon
- lettuceLactuca sativat0
- Treatment
- elevated RZ [CO2]e0
- Outcome
- biomasse0
- Direction
- moree0
- Comparator
- ambient RZ [CO2]e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All plants accumulated more biomass at elevated RZ [CO2] than at ambient RZ [CO2]”
t0“lettuce”
Claim · model-written summary
Elevated root-zone CO2 lowered shoot/root ratios through larger root than shoot biomass gains.
- Taxon
- lettuceLactuca sativat0
- Treatment
- elevated RZ [CO2]e0
- Outcome
- shoot/root ratiose0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Greater increases of biomass in roots than in shoots were manifested by lower shoot/root ratios at elevated RZ [CO2]”
t0“lettuce”
Claim · model-written summary
Total biomass was higher at 20°C root-zone temperature.
- Taxon
- lettuceLactuca sativat0
- Treatment
- 20°C-RZTe0
- Outcome
- total biomasse0
- Direction
- highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total biomass was higher at 20°C-RZT”
t0“lettuce”
Claim · model-written summary
The biomass response to elevated CO2 was greater at ambient than 20°C root-zone temperature.
- Taxon
- lettuceLactuca sativat0
- Treatment
- elevated RZ [CO2]e0
- Outcome
- increase in biomasse0
- Direction
- greatere0
- Setting
- A-RZTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increase in biomass under elevated RZ [CO2] was greater at A-RZT”
t0“lettuce”
Claim · model-written summary
Elevated CO2 increased shoot nitrate and total reduced nitrogen concentrations at both temperatures.
- Taxon
- lettuceLactuca sativat0
- Treatment
- elevated RZ [CO2]e0
- Outcome
- Shoot NO3 - and TRN concentrationse0
- Direction
- highere0
- Comparator
- ambient RZ [CO2]e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot NO3 - and TRN concentrations, total leaf soluble and Rubisco protein concentrations were higher in all elevated RZ [CO2] plants than in plants under ambient RZ [CO2] at both RZTs”
t0“lettuce”
Claim · model-written summary
Elevated CO2 increased soluble and Rubisco protein concentrations.
- Taxon
- lettuceLactuca sativat0
- Treatment
- elevated RZ [CO2]e0
- Outcome
- total leaf soluble and Rubisco protein concentrationse0
- Direction
- highere0
- Comparator
- ambient RZ [CO2]e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot NO3 - and TRN concentrations, total leaf soluble and Rubisco protein concentrations were higher in all elevated RZ [CO2] plants than in plants under ambient RZ [CO2] at both RZTs”
t0“lettuce”
Claim · model-written summary
At each CO2 level, soluble and Rubisco protein concentrations were higher at 20°C than ambient temperature.
- Taxon
- lettuceLactuca sativat0
- Treatment
- 20°C-RZTe0
- Outcome
- total leaf soluble and Rubisco protein concentrationse0
- Direction
- highere0
- Comparator
- A-RZTe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under each RZ [CO2], total leaf soluble and Rubisco protein concentrations were significantly higher at 20°C-RZT than at A-RZT”
t0“lettuce”
Claim · model-written summary
Authors attributed greater photosynthesis and productivity under elevated CO2 partly to less water loss and photoinhibition and higher Calvin cycle turnover.
- Taxon
- lettuceLactuca sativat0
- Outcome
- increased P Nmax and productivitye0
- Qualifier
- alleviation of midday water loss, both dynamic and chronic photoinhibition as well as higher turnover of Calvin cycle with higher Rubisco proteinse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“increased P Nmax and productivity under elevated [CO2] was partially due to the alleviation of midday water loss, both dynamic and chronic photoinhibition as well as higher turnover of Calvin cycle with higher Rubisco proteins”
t0“lettuce”
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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.