Abstract
Leaf gas exchange characteristics for 16 species of cycad were determined under field conditions in Miami, Fla. Net CO 2 assimilation (A CO2 ) ranged from 4.9 μmol·m -2 ·s -1 for Lepidozamia peroffskyana Regel to 10.1 μmol·m -2 ·s -1 for Zamia furfuracea L. fil. in Aiton. Stomatal conductance to H 2 O (g s ) was more variable, ranging from 85 mmol·m -2 ·s -1 for Cycas seemannii A. Br. to 335 mmol·m -2 ·s -1 for Encephalartos hildebrandtii A. Br. & Bouche. Transpiration (E) ranged from 1.7 mmol·m -2 ·s -1 for Cycas chamberlainii W.H. Brown & Keinholz to 4.8 mmol·m -2 ·s -1 for Encephalartos hildebrandtii. Highly variable E was more controlling of water-use efficiency than the less-variable A CO2 . The difference between air and pinnae temperature ranged from 0.3 to 1.6 °C and was inversely related to mean g s among the species. The values within geographic regions representative of the native habitats of the species were highly variable. For example, two of the African species exhibited the highest and lowest values of water-use efficiency in the survey. Leaf gas exchange for the four largest species with arborescent growth form was less than that for the three small species with subterranean or short bulbous growth form. The diurnal variation in leaf gas exchange for Zamia furfuracea exhibited a two-peaked pattern with a distinct midday depression in A CO2 and g s . The ratio of dark respiration to maximum A CO2 for Zamia furfuracea was 0.04. As a group, the values for A CO2 and g s for these cycads ranked at the lower end of the range for all plants species.
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Claims 16
Claim · model-written summary
Net CO2 assimilation ranged from 4.9 for Lepidozamia peroffskyana to 10.1 μmol·m -2 ·s -1 for Zamia furfuracea.
- Taxon
- Lepidozamia peroffskyana Regel
Lepidozamia peroffskyanae0 - Outcome
- Net CO 2 assimilatione0
- Direction
- ranged frome0
- Value
- 4.9 μmol·m -2 ·s -1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Net CO 2 assimilation (A CO2 ) ranged from 4.9 μmol·m -2 ·s -1 for Lepidozamia peroffskyana Regel to 10.1 μmol·m -2 ·s -1 for Zamia furfuracea L. fil. in Aiton.”
Claim · model-written summary
Zamia furfuracea reached 10.1 μmol·m -2 ·s -1 net CO2 assimilation.
- Taxon
- Zamia furfuracea L. fil. in Aiton
Zamia furfuraceae0 - Outcome
- Net CO 2 assimilatione0
- Direction
- ranged frome0
- Value
- 10.1 μmol·m -2 ·s -1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Net CO 2 assimilation (A CO2 ) ranged from 4.9 μmol·m -2 ·s -1 for Lepidozamia peroffskyana Regel to 10.1 μmol·m -2 ·s -1 for Zamia furfuracea L. fil. in Aiton.”
Claim · model-written summary
Cycas seemannii had stomatal conductance of 85 mmol·m -2 ·s -1.
- Taxon
- Cycas seemannii A. Br.
Cycas seemanniie0 - Outcome
- Stomatal conductance to H 2 Oe0
- Direction
- ranging frome0
- Value
- 85 mmol·m -2 ·s -1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Stomatal conductance to H 2 O (g s ) was more variable, ranging from 85 mmol·m -2 ·s -1 for Cycas seemannii A. Br. to 335 mmol·m -2 ·s -1 for Encephalartos hildebrandtii A. Br. & Bouche.”
Claim · model-written summary
Encephalartos hildebrandtii had stomatal conductance of 335 mmol·m -2 ·s -1.
- Taxon
- Encephalartos hildebrandtii A. Br. & Bouche
.JPG?width=60)
Encephalartos hildebrandtiie0 - Outcome
- Stomatal conductance to H 2 Oe0
- Direction
- ranging frome0
- Value
- 335 mmol·m -2 ·s -1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.JPG?width=500)
Verbatim
e0“Stomatal conductance to H 2 O (g s ) was more variable, ranging from 85 mmol·m -2 ·s -1 for Cycas seemannii A. Br. to 335 mmol·m -2 ·s -1 for Encephalartos hildebrandtii A. Br. & Bouche.”
Claim · model-written summary
Cycas chamberlainii transpiration was 1.7 mmol·m -2 ·s -1.
- Taxon
- Cycas chamberlainii W.H. Brown & Keinholz
Cycas chamberlainiie0 - Outcome
- Transpiratione0
- Direction
- ranged frome0
- Value
- 1.7 mmol·m -2 ·s -1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transpiration (E) ranged from 1.7 mmol·m -2 ·s -1 for Cycas chamberlainii W.H. Brown & Keinholz to 4.8 mmol·m -2 ·s -1 for Encephalartos hildebrandtii.”
Claim · model-written summary
Encephalartos hildebrandtii transpiration was 4.8 mmol·m -2 ·s -1.
- Taxon
- Encephalartos hildebrandtiiEncephalartos hildebrandtiie0
- Outcome
- Transpiratione0
- Direction
- ranged frome0
- Value
- 4.8 mmol·m -2 ·s -1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transpiration (E) ranged from 1.7 mmol·m -2 ·s -1 for Cycas chamberlainii W.H. Brown & Keinholz to 4.8 mmol·m -2 ·s -1 for Encephalartos hildebrandtii.”
Claim · model-written summary
Variable transpiration controlled water-use efficiency more than less-variable assimilation.
Verbatim
e0“Highly variable E was more controlling of water-use efficiency than the less-variable A CO2 .”
t0“Cycad Species”
Claim · model-written summary
The air-to-pinnae temperature difference ranged from 0.3 to 1.6 °C.
Verbatim
e0“The difference between air and pinnae temperature ranged from 0.3 to 1.6 °C”
t0“Cycad Species”
Claim · model-written summary
The air-to-pinnae temperature difference was inversely associated with mean stomatal conductance.
Verbatim
e0“The difference between air and pinnae temperature ranged from 0.3 to 1.6 °C and was inversely related to mean g s among the species.”
t0“Cycad Species”
Claim · model-written summary
Gas-exchange values varied substantially within native-habitat geographic regions.
Verbatim
e0“The values within geographic regions representative of the native habitats of the species were highly variable.”
t0“Cycad Species”
Claim · model-written summary
Two African species had the highest and lowest water-use efficiency in the survey.
Verbatim
e0“two of the African species exhibited the highest and lowest values of water-use efficiency in the survey.”
t0“Cycad Species”
Claim · model-written summary
Four large arborescent species had lower leaf gas exchange than three small subterranean or short bulbous species.
Verbatim
e0“Leaf gas exchange for the four largest species with arborescent growth form was less than that for the three small species with subterranean or short bulbous growth form.”
t0“Cycad Species”
Claim · model-written summary
Zamia furfuracea had a two-peaked diurnal leaf gas-exchange pattern.
- Taxon
- Zamia furfuraceaZamia furfuraceae0
- Outcome
- two-peaked patterne0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The diurnal variation in leaf gas exchange for Zamia furfuracea exhibited a two-peaked pattern with a distinct midday depression in A CO2 and g s .”
Claim · model-written summary
Zamia furfuracea had midday depression in assimilation and stomatal conductance.
- Taxon
- Zamia furfuraceaZamia furfuraceae0
- Outcome
- midday depression in A CO2 and g se0
- Direction
- depressione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The diurnal variation in leaf gas exchange for Zamia furfuracea exhibited a two-peaked pattern with a distinct midday depression in A CO2 and g s .”
Claim · model-written summary
Zamia furfuracea dark respiration to maximum assimilation ratio was 0.04.
- Taxon
- Zamia furfuraceaZamia furfuraceae0
- Outcome
- ratio of dark respiration to maximum A CO2e0
- Value
- 0.04e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The ratio of dark respiration to maximum A CO2 for Zamia furfuracea was 0.04.”
Claim · model-written summary
As a group, cycads had assimilation and conductance values near the lower end of the plant range.
- Taxon
- cycadsCycadopsidae0
- Outcome
- values for A CO2 and g se0
- Direction
- lower ende0
- Comparator
- all plants speciese0
Verbatim
e0“As a group, the values for A CO2 and g s for these cycads ranked at the lower end of the range for all plants species.”