Abstract
Lettuce ( Lactuca sativa L. cv. Summer-green) plug transplants were grown for 3 weeks under 16 combinations of four levels (100, 150, 200, and 300 μmol·m -2 ·s -1 ) of photosynthetic photon flux ( PPF ), two photoperiods (16 and 24 h), and two levels of CO 2 (400 and 800 μmol·mol -1 ) in growth chambers maintained at an air temperature of 20 ±2 °C. As PPF increased, dry mass (DM), percent DM, and leaf number increased, while ratio of shoot to root dry mass (S/R), ratio of leaf length to leaf width (LL/LW), specific leaf area, and hypocotyl length decreased. At the same PPF, DM was increased by 25% to 100% and 10% to 100% with extended photoperiod and elevated CO 2 concentration, respectively. Dry mass, percent DM, and leaf number increased linearly with daily light integral (DLI, the product of PPF and photoperiod), while S/R, specific leaf area, LL/LW and hypocotyl length decreased as DLI increased under each CO 2 concentration. Hypocotyl length was influenced by PPF and photoperiod, but not by CO 2 concentration. Leaf morphology, which can be reflected by LL/LW, was substantially influenced by PPF at 100 to 200 μmol·m -2 ·s -1 , but not at 200 to 300 μmol·m -2 ·s -1 . At the same DLI, the longer photoperiod promoted growth under the low CO 2 concentration, but not under the high CO 2 concentration. Longer photoperiod and/or higher CO 2 concentration compensated for a low PPF.
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Claims 13
Claim · model-written summary
Increasing PPF raised dry mass, percent dry mass, and leaf number.
- Taxon
- Lettuce
Lactuca sativat0 - Treatment
- PPFe0
- Outcome
- dry mass (DM), percent DM, and leaf numbere0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“As PPF increased, dry mass (DM), percent DM, and leaf number increased”
t0“Lettuce”
Claim · model-written summary
Increasing PPF reduced shoot to root mass ratio, leaf shape ratio, and specific leaf area.
- Taxon
- LettuceLactuca sativat0
- Treatment
- PPFe1
- Outcome
- ratio of shoot to root dry mass (S/R), ratio of leaf length to leaf width (LL/LW), specific leaf areae0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while ratio of shoot to root dry mass (S/R), ratio of leaf length to leaf width (LL/LW), specific leaf area, and hypocotyl length decreased”
e1“As PPF increased”
t0“Lettuce”
Claim · model-written summary
Increasing PPF reduced hypocotyl length.
- Taxon
- LettuceLactuca sativat0
- Treatment
- PPFe1
- Outcome
- hypocotyl lengthe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“while ratio of shoot to root dry mass (S/R), ratio of leaf length to leaf width (LL/LW), specific leaf area, and hypocotyl length decreased”
e1“As PPF increased”
t0“Lettuce”
Claim · model-written summary
Extended photoperiod raised dry mass by 25% to 100% at the same PPF.
- Taxon
- LettuceLactuca sativat0
- Treatment
- extended photoperiode0
- Outcome
- DMe0
- Direction
- increasede0
- Value
- 25% to 100%e0
- Comparator
- same PPFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the same PPF, DM was increased by 25% to 100% and 10% to 100% with extended photoperiod and elevated CO 2 concentration, respectively”
t0“Lettuce”
Claim · model-written summary
Elevated CO2 raised dry mass by 10% to 100% at the same PPF.
- Taxon
- LettuceLactuca sativat0
- Treatment
- elevated CO 2 concentratione0
- Outcome
- DMe0
- Direction
- increasede0
- Value
- 10% to 100%e0
- Comparator
- same PPFe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the same PPF, DM was increased by 25% to 100% and 10% to 100% with extended photoperiod and elevated CO 2 concentration, respectively”
t0“Lettuce”
Claim · model-written summary
Dry mass, percent dry mass, and leaf number increased with daily light integral.
- Taxon
- LettuceLactuca sativat0
- Treatment
- daily light integrale0
- Outcome
- Dry mass, percent DM, and leaf numbere0
- Direction
- increasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Dry mass, percent DM, and leaf number increased linearly with daily light integral (DLI, the product of PPF and photoperiod)”
t0“Lettuce”
Claim · model-written summary
Shoot to root ratio, specific leaf area, and leaf shape ratio decreased with daily light integral.
- Taxon
- LettuceLactuca sativat0
- Treatment
- DLIe0
- Outcome
- S/R, specific leaf area, LL/LWe0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“S/R, specific leaf area, LL/LW and hypocotyl length decreased as DLI increased under each CO 2 concentration”
t0“Lettuce”
Claim · model-written summary
Hypocotyl length decreased with daily light integral.
- Taxon
- LettuceLactuca sativat0
- Treatment
- DLIe0
- Outcome
- hypocotyl lengthe0
- Direction
- decreasede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“hypocotyl length decreased as DLI increased under each CO 2 concentration”
t0“Lettuce”
Claim · model-written summary
CO2 concentration did not influence hypocotyl length.
- Taxon
- LettuceLactuca sativat0
- Treatment
- CO 2 concentratione0
- Outcome
- Hypocotyl lengthe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hypocotyl length was influenced by PPF and photoperiod, but not by CO 2 concentration”
t0“Lettuce”
Claim · model-written summary
PPF substantially influenced leaf shape ratio at 100 to 200 but not 200 to 300 micromoles.
- Taxon
- LettuceLactuca sativat0
- Treatment
- PPFe0
- Outcome
- LL/LWe0
- Qualifier
- 100 to 200 μmol·m -2 ·s -1e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Leaf morphology, which can be reflected by LL/LW, was substantially influenced by PPF at 100 to 200 μmol·m -2 ·s -1 , but not at 200 to 300 μmol·m -2 ·s -1”
t0“Lettuce”
Claim · model-written summary
At equal daily light integral, longer photoperiod promoted growth under low CO2.
- Taxon
- LettuceLactuca sativat0
- Treatment
- longer photoperiode0
- Outcome
- growthe0
- Direction
- promotede0
- Qualifier
- low CO 2 concentratione0
- Comparator
- same DLIe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the same DLI, the longer photoperiod promoted growth under the low CO 2 concentration”
t0“Lettuce”
Claim · model-written summary
At equal daily light integral, longer photoperiod did not promote growth under high CO2.
- Taxon
- LettuceLactuca sativat0
- Treatment
- longer photoperiode0
- Outcome
- growthe0
- Qualifier
- high CO 2 concentratione0
- Comparator
- same DLIe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the same DLI, the longer photoperiod promoted growth under the low CO 2 concentration, but not under the high CO 2 concentration”
t0“Lettuce”
Claim · model-written summary
Longer photoperiod and higher CO2 compensated for low PPF.
- Taxon
- LettuceLactuca sativat0
- Treatment
- Longer photoperiod and/or higher CO 2 concentratione0
- Outcome
- compensated for a low PPFe0
- Comparator
- low PPFe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Longer photoperiod and/or higher CO 2 concentration compensated for a low PPF”
t0“Lettuce”
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