Abstract
Photosynthesis and concurrent export rates of expanded leaves on the flowering shoot of Rosa hybrida L. `Samantha' were measured at three stages of shoot and flower bud development. At 35 and 90 Pa CO 2 photosynthesis and concurrent export rates of the upper expanded leaves were greater at Stage 3 (i.e., when petal color of the flower bud was visible) than at the two earlier stages of shoot and flower development. The optimum for leaf photosynthesis and concurrent export at ambient CO 2 and saturating irradiance were ≈25 °C. Export was more sensitive to increased temperature than was carbon fixation. For example, at 40 °C photosynthesis was 40% lower while the export rate during photosynthesis was reduced by 80%. Increasing the photon fluence flux rate from 200 to 1000 μmol·m -2 ·s -1 PAR increased the photosynthetic rate and the concurrent export rate at 35 and 90 Pa CO 2 , but the increase in export was proportionally greater than that of photosynthesis. At 35 Pa CO 2 , the rate of C export during photosynthesis increased from 31 to 59% of the concurrent C fixation rate. At 90 Pa CO 2 , export during photosynthesis increased from 38 to 62% of the photosynthesis rate. The importance of irradiance on translocation processes was further demonstrated by comparing the disappearance of label during the feed period and during an extended night period. Plants grown at each CO 2 level exported about three times as much of the 14 C fixed during a 2-hour feed period in the light as during a subsequent 15-hour dark chase period. The nighttime export and respiration rates of leaves which had been exposed to elevated CO 2 levels during the feed were higher than those rates observed at ambient CO 2 . However, at the end of the chase period, the leaves of plants which had been exposed to CO 2 enrichment during the feed also retained more 14 C than did the leaves of the plants which were at ambient CO 2 . Thus, although more 14 C was fixed and exported under high CO 2 , the same proportion of labelled assimilates were exported, respired, and retained in the dark as at ambient CO 2 .
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Claims 12
Claim · model-written summary
At both CO2 levels, stage 3 leaves had greater photosynthesis and carbon export than earlier stages.
- Taxon
- Rosa hybrida
Rosa hybrid cultivare1 - Organ / stage
- upper expanded leavese0
- Outcome
- photosynthesis and concurrent export ratese0
- Direction
- greatere0
- Qualifier
- At 35 and 90 Pa CO 2e0
- Comparator
- the two earlier stages of shoot and flower developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 35 and 90 Pa CO 2 photosynthesis and concurrent export rates of the upper expanded leaves were greater at Stage 3 (i.e., when petal color of the flower bud was visible) than at the two earlier stages of shoot and flower development”
e1“Rosa hybrida L.”
Claim · model-written summary
Leaf photosynthesis and export were optimal near 25 °C at ambient CO2 and saturating light.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Outcome
- leaf photosynthesis and concurrent exporte0
- Direction
- optimume0
- Value
- ≈25 °Ce0
- Qualifier
- ambient CO 2 and saturating irradiancee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The optimum for leaf photosynthesis and concurrent export at ambient CO 2 and saturating irradiance were ≈25 °C”
e1“Rosa hybrida L.”
Claim · model-written summary
At 40 °C, photosynthesis was 40% lower.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Outcome
- photosynthesise0
- Direction
- lowere0
- Value
- 40%e0
- Qualifier
- at 40 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at 40 °C photosynthesis was 40% lower while the export rate during photosynthesis was reduced by 80%”
e1“Rosa hybrida L.”
Claim · model-written summary
At 40 °C, export during photosynthesis was reduced by 80%.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Outcome
- export rate during photosynthesise0
- Direction
- reducede0
- Value
- 80%e0
- Qualifier
- at 40 °Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“at 40 °C photosynthesis was 40% lower while the export rate during photosynthesis was reduced by 80%”
e1“Rosa hybrida L.”
Claim · model-written summary
Increasing light from 200 to 1000 PAR increased photosynthesis at both CO2 levels.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Treatment
- Increasing the photon fluence flux rate from 200 to 1000 μmol·m -2 ·s -1 PARe0
- Outcome
- photosynthetic ratee0
- Direction
- increasede0
- Qualifier
- at 35 and 90 Pa CO 2e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing the photon fluence flux rate from 200 to 1000 μmol·m -2 ·s -1 PAR increased the photosynthetic rate and the concurrent export rate at 35 and 90 Pa CO 2”
e1“Rosa hybrida L.”
Claim · model-written summary
Increasing light increased concurrent export at both CO2 levels.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Treatment
- Increasing the photon fluence flux rate from 200 to 1000 μmol·m -2 ·s -1 PARe0
- Outcome
- concurrent export ratee0
- Direction
- increasede0
- Qualifier
- at 35 and 90 Pa CO 2e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing the photon fluence flux rate from 200 to 1000 μmol·m -2 ·s -1 PAR increased the photosynthetic rate and the concurrent export rate at 35 and 90 Pa CO 2”
e1“Rosa hybrida L.”
Claim · model-written summary
At 35 Pa CO2, carbon export rose from 31% to 59% of fixation with increased irradiance.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Outcome
- rate of C export during photosynthesise0
- Direction
- increasede0
- Value
- 31 to 59%e0
- Qualifier
- At 35 Pa CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 35 Pa CO 2 , the rate of C export during photosynthesis increased from 31 to 59% of the concurrent C fixation rate”
e1“Rosa hybrida L.”
Claim · model-written summary
At 90 Pa CO2, export rose from 38% to 62% of photosynthesis with increased irradiance.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Outcome
- export during photosynthesise0
- Direction
- increasede0
- Value
- 38 to 62%e0
- Qualifier
- At 90 Pa CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 90 Pa CO 2 , export during photosynthesis increased from 38 to 62% of the photosynthesis rate”
e1“Rosa hybrida L.”
Claim · model-written summary
Plants exported about three times as much fixed carbon in light as in dark chase.
Verbatim
e0“Plants grown at each CO 2 level exported about three times as much of the 14 C fixed during a 2-hour feed period in the light as during a subsequent 15-hour dark chase period”
Claim · model-written summary
Elevated CO2 during feeding increased nighttime export and respiration relative to ambient CO2.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Treatment
- elevated CO 2 levelse0
- Outcome
- nighttime export and respiration ratese0
- Direction
- highere0
- Comparator
- ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nighttime export and respiration rates of leaves which had been exposed to elevated CO 2 levels during the feed were higher than those rates observed at ambient CO 2”
e1“Rosa hybrida L.”
Claim · model-written summary
CO2-enriched leaves retained more labeled carbon at the end of the dark chase.
Verbatim
e0“the leaves of plants which had been exposed to CO 2 enrichment during the feed also retained more 14 C than did the leaves of the plants which were at ambient CO 2”
Claim · model-written summary
The fractions exported, respired, and retained in darkness were equal under high and ambient CO2.
- Taxon
- Rosa hybridaRosa hybrid cultivare1
- Treatment
- high CO 2e0
- Outcome
- proportion of labelled assimilates were exported, respired, and retainede0
- Direction
- samee0
- Comparator
- ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Thus, although more 14 C was fixed and exported under high CO 2 , the same proportion of labelled assimilates were exported, respired, and retained in the dark as at ambient CO 2”
e1“Rosa hybrida L.”
The same questions in other papers
light · physiology: photosynthesis · Rosa hybrid cultivarPositive and negative results
3 papers in the same direction as this paper · 3 in the opposite direction
- negative
- negative
- negative
3 papers more in this group
See all 7 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.