Abstract
Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium. Determinations of chlorophyll a fluorescence were used to estimate relative changes in electron transport rate. Alterations in leaf mass per unit area, which-on a short-term basis-largely reflect changes in water content, were recorded continuously with a beta-gauge. Turgor pressure of mesophyll cells was determined with a pressure probe. As reported previously (K Winter, DJ von Willert [1972] Z Pflanzenphysiol 67: 166-170), recently expanded leaves of plants grown under nonsaline conditions showed gas-exchange characteristics of a C(3) plant. Although these plants were not exposed to any particular stress treatment, water content and turgor pressure regularly decreased toward the end of the 12 hour light periods and recovered during the following 12 hours of darkness. When the NaCl concentration of the rooting medium was raised to 400 millimolar, in increments of 100 millimolar given at the onset of the photoperiods for 4 consecutive days, leaf water content and turgor pressure decreased by as much as 30 and 60%, respectively, during the course of the photoperiods. These transient decreases probably triggered the induction of the biochemical machinery which is required for CAM to operate. After several days at 400 millimolar NaCl, when leaves showed features typical of CAM, overall turgor pressure and leaf mass per unit area had increased above the levels before onset of the salt treatment, and diurnal alterations in leaf water content were reduced. Net carbon gain during photoperiods and average intercellular CO(2) partial pressures at which net CO(2) uptake occurred, progressively decreased upon salinization. Reversible diurnal depressions in leaf conductance and net CO(2) uptake, with minima recorded in the middle of the photoperiods, preceded the occurrence of nocturnal net CO(2) uptake. During these reductions, intercellular CO(2) partial pressure and rates of photosynthetic electron transport decreased. With advancing age, leaves of plants grown under nonsaline conditions exhibited progressively greater diurnal reductions in turgor pressure and developed a low degree of CAM activity.
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Claims 10
Claim · model-written summary
Leaf water content and turgor pressure decreased by as much as 30% and 60% during the photoperiods under NaCl.
- Taxon
- Mesembryanthemum crystallinum
Mesembryanthemum crystallinume0 - Treatment
- high NaCl salinitye0
- Outcome
- leaf water content and turgor pressuree1
- Direction
- decreasede1
- Value
- 30 and 60%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e1“leaf water content and turgor pressure decreased by as much as 30 and 60%, respectively, during the course of the photoperiods”
Claim · model-written summary
Net carbon gain during photoperiods and average intercellular CO2 partial pressures progressively decreased upon salinization.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Treatment
- salinizatione2
- Outcome
- Net carbon gain during photoperiods and average intercellular CO(2) partial pressurese2
- Direction
- progressively decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e2“Net carbon gain during photoperiods and average intercellular CO(2) partial pressures at which net CO(2) uptake occurred, progressively decreased upon salinization”
Claim · model-written summary
Reversible diurnal depressions in leaf conductance and net CO2 uptake preceded nocturnal net CO2 uptake.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Treatment
- Reversible diurnal depressions in leaf conductance and net CO(2) uptakee3
- Outcome
- nocturnal net CO(2) uptakee3
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e3“Reversible diurnal depressions in leaf conductance and net CO(2) uptake, with minima recorded in the middle of the photoperiods, preceded the occurrence of nocturnal net CO(2) uptake”
Claim · model-written summary
During the depressions, intercellular CO2 partial pressure and rates of photosynthetic electron transport decreased.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Treatment
- these reductionse4
- Outcome
- intercellular CO(2) partial pressure and rates of photosynthetic electron transporte4
- Direction
- decreasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e4“During these reductions, intercellular CO(2) partial pressure and rates of photosynthetic electron transport decreased”
Claim · model-written summary
With advancing age, leaves under nonsaline conditions showed progressively greater diurnal reductions in turgor pressure.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Treatment
- advancing agee5
- Outcome
- diurnal reductions in turgor pressuree5
- Direction
- greatere5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e5“With advancing age, leaves of plants grown under nonsaline conditions exhibited progressively greater diurnal reductions in turgor pressure and developed a low degree of CAM activity”
Claim · model-written summary
Leaves grown under nonsaline conditions developed a low degree of CAM activity with advancing age.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Outcome
- CAM activitye5
- Value
- low degree of CAM activitye5
- Setting
- nonsaline conditionse5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e5“With advancing age, leaves of plants grown under nonsaline conditions exhibited progressively greater diurnal reductions in turgor pressure and developed a low degree of CAM activity”
Claim · model-written summary
After several days at 400 millimolar NaCl, overall turgor pressure and leaf mass per unit area increased above the levels before the salt treatment.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Treatment
- 400 millimolar NaCle6
- Outcome
- overall turgor pressure and leaf mass per unit areae6
- Direction
- increasede6
- Comparator
- the levels before onset of the salt treatmente6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e6“After several days at 400 millimolar NaCl, when leaves showed features typical of CAM, overall turgor pressure and leaf mass per unit area had increased above the levels before onset of the salt treatment”
Claim · model-written summary
Under 400 millimolar NaCl, diurnal alterations in leaf water content were reduced.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Treatment
- 400 millimolar NaCle6
- Outcome
- diurnal alterations in leaf water contente7
- Direction
- reducede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e6“After several days at 400 millimolar NaCl, when leaves showed features typical of CAM, overall turgor pressure and leaf mass per unit area had increased above the levels before onset of the salt treatment”
e7“diurnal alterations in leaf water content were reduced”
Claim · model-written summary
Water content and turgor pressure regularly decreased toward the end of the 12 hour light periods in plants grown under nonsaline conditions.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Outcome
- water content and turgor pressuree7
- Direction
- decreasede7
- Qualifier
- toward the end of the 12 hour light periodse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e7“water content and turgor pressure regularly decreased toward the end of the 12 hour light periods”
Claim · model-written summary
Transient decreases in leaf water content probably triggered induction of the biochemical machinery required for CAM.
- Taxon
- Mesembryanthemum crystallinumMesembryanthemum crystallinume0
- Outcome
- induction of the biochemical machinerye6
- Qualifier
- transient decreasese6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Simultaneous measurements of net CO(2) exchange, water vapor exchange, and leaf water relations were performed in Mesembryanthemum crystallinum during the development of crassulacean acid metabolism (CAM) in response to high NaCl salinity in the rooting medium”
e6“These transient decreases probably triggered the induction of the biochemical machinery which is required for CAM to operate”