Abstract
Sodium chloride, at a concentration of 88 mol m −3 in half strength Hoagland nutrient solution, increased dry weight per unit area of Xanthium strumarium L. leaves by 19%, and chlorophyll by 45% compared to plants grown without added NaCl at ambient (350 μmol mol −1 ) CO 2 concentration. Photosynthesis, per unit leaf area, was almost unaffected. Even so, over a 4-week period, growth (dry weight increment) was reduced in the salt treatment by 50%. This could be ascribed to a large reduction in leaf area (>60%) and to an approx. 20% increase in the rate of dark respiration (Rd). Raising ambient [CO 2 ] from zero to 2000 μmol mol −1 decreased Rd in both control and salinized plants (by 20% at 1000, and by 50% at 2000 μmol mol −1 CO 2 concentration) compared to Rd in the absence of ambient CO 2 . High night-time [CO 2 ] had no significant effect on growth of non-salinized plants, irrespective of day-time ambient [CO 2 ]. Growth reduction caused by salt was reduced from 51% in plants grown in 350 μmol mol −1 throughout the day, to 31% in those grown continuously in 900 μmol mol −1 [CO 2 ]. The effect of [CO 2 ] at night on salinized plants depended on the daytime CO 2 concentration. Under 350 μmol mol −1 day-time [CO 2 ], 900 μmol mol −1 at night reduced growth over a 4-week period by 9% ( P <0.05) and 1700 μmol mol −1 reduced it by 14% ( P <0.01). However, under 900 μmol mol −1 day-time [CO 2 ], 900 vs . 350 μmol mol −1 [CO 2 ] at night increased growth by 17% ( P <0.01). It is concluded that there is both a functional and an otiose (functionless) component to Rd, which is increased by salt. Under conditions of low photosynthesis (such as here, in the low day-time [CO 2 ] regime) the otiose component is small and high night-time [CO 2 ] partly suppresses functional Rd, thereby reducing salt tolerance. In plants growing under conditions which stimulate photosynthesis (e.g. with increased daytime [CO 2 ]), elevated [CO 2 ] at night suppresses mainly the otiose component of respiration, thus increasing growth. Consequently, in regions of adequate water and sunlight, the predicted further elevation of the world atmospheric [CO 2 ] may increase plant salinity tolerance.
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Claims 17
Claim · model-written summary
NaCl increased leaf dry weight per unit area by 19% under ambient CO2.
- Taxon
- Xanthium strumarium L.
Xanthium strumariume0 - Treatment
- Sodium chloride, at a concentration of 88 mol m −3e0
- Outcome
- dry weight per unit area of Xanthium strumarium L. leavese0
- Direction
- increasede0
- Value
- 19%e0
- Comparator
- plants grown without added NaCle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sodium chloride, at a concentration of 88 mol m −3 in half strength Hoagland nutrient solution, increased dry weight per unit area of Xanthium strumarium L. leaves by 19%, and chlorophyll by 45% compared to plants grown without added NaCl at ambient (350 μmol mol −1 ) CO 2 concentration”
Claim · model-written summary
NaCl increased leaf chlorophyll by 45% under ambient CO2.
- Taxon
- Xanthium strumarium L.Xanthium strumariume0
- Treatment
- Sodium chloride, at a concentration of 88 mol m −3e0
- Outcome
- chlorophylle0
- Direction
- increasede0
- Value
- 45%e0
- Comparator
- plants grown without added NaCle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sodium chloride, at a concentration of 88 mol m −3 in half strength Hoagland nutrient solution, increased dry weight per unit area of Xanthium strumarium L. leaves by 19%, and chlorophyll by 45% compared to plants grown without added NaCl at ambient (350 μmol mol −1 ) CO 2 concentration”
Claim · model-written summary
Leaf-area photosynthesis was almost unaffected by NaCl.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- NaCle1
- Outcome
- Photosynthesis, per unit leaf areae0
- Direction
- almost unaffectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Photosynthesis, per unit leaf area, was almost unaffected”
e1“plants grown without added NaCl”
t0“Xanthium strumarium”
Claim · model-written summary
Salt reduced four-week dry weight growth by 50%.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- salt treatmente0
- Outcome
- growth (dry weight increment)e0
- Direction
- reducede0
- Value
- 50%e0
- Qualifier
- over a 4-week periode0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“over a 4-week period, growth (dry weight increment) was reduced in the salt treatment by 50%”
t0“Xanthium strumarium”
Claim · model-written summary
Salt reduced leaf area by more than 60%.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- salt treatmente1
- Outcome
- leaf areae0
- Direction
- reductione0
- Value
- >60%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“large reduction in leaf area (>60%)”
e1“salt treatment”
t0“Xanthium strumarium”
Claim · model-written summary
Salt increased dark respiration by about 20%.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- salt treatmente1
- Outcome
- rate of dark respiration (Rd)e0
- Direction
- increasee0
- Value
- approx. 20%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“approx. 20% increase in the rate of dark respiration (Rd)”
e1“salt treatment”
t0“Xanthium strumarium”
Claim · model-written summary
At 1000 μmol mol −1 CO2, dark respiration decreased by 20% relative to zero ambient CO2.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- 1000e0
- Outcome
- Rde0
- Direction
- decreasede0
- Value
- 20%e0
- Comparator
- absence of ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Raising ambient [CO 2 ] from zero to 2000 μmol mol −1 decreased Rd in both control and salinized plants (by 20% at 1000, and by 50% at 2000 μmol mol −1 CO 2 concentration) compared to Rd in the absence of ambient CO 2”
t0“Xanthium strumarium”
Claim · model-written summary
At 2000 μmol mol −1 CO2, dark respiration decreased by 50% relative to zero ambient CO2.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- 2000 μmol mol −1 CO 2 concentratione0
- Outcome
- Rde0
- Direction
- decreasede0
- Value
- 50%e0
- Comparator
- absence of ambient CO 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Raising ambient [CO 2 ] from zero to 2000 μmol mol −1 decreased Rd in both control and salinized plants (by 20% at 1000, and by 50% at 2000 μmol mol −1 CO 2 concentration) compared to Rd in the absence of ambient CO 2”
t0“Xanthium strumarium”
Claim · model-written summary
High nighttime CO2 had no significant effect on growth without salt across daytime CO2 conditions.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- High night-time [CO 2 ]e0
- Outcome
- growth of non-salinized plantse0
- Direction
- no significant effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“High night-time [CO 2 ] had no significant effect on growth of non-salinized plants, irrespective of day-time ambient [CO 2 ]”
t0“Xanthium strumarium”
Claim · model-written summary
Continuous 900 μmol mol −1 CO2 lessened salt growth reduction to 31%, versus 51% at 350 μmol mol −1.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- 900 μmol mol −1 [CO 2 ]e0
- Outcome
- Growth reduction caused by salte0
- Direction
- reducede0
- Value
- 31%e0
- Qualifier
- 51%e0
- Comparator
- 350 μmol mol −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Growth reduction caused by salt was reduced from 51% in plants grown in 350 μmol mol −1 throughout the day, to 31% in those grown continuously in 900 μmol mol −1 [CO 2 ]”
t0“Xanthium strumarium”
Claim · model-written summary
With daytime CO2 at 350, nighttime CO2 at 900 reduced growth by 9%.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- 900 μmol mol −1 at nighte0
- Outcome
- growthe0
- Direction
- reducede0
- Value
- 9%e0
- Qualifier
- Under 350 μmol mol −1 day-time [CO 2 ]e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under 350 μmol mol −1 day-time [CO 2 ], 900 μmol mol −1 at night reduced growth over a 4-week period by 9% ( P <0.05)”
t0“Xanthium strumarium”
Claim · model-written summary
With daytime CO2 at 350, nighttime CO2 at 1700 reduced growth by 14%.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- 1700 μmol mol −1e0
- Outcome
- growthe0
- Direction
- reducede0
- Value
- 14%e0
- Qualifier
- Under 350 μmol mol −1 day-time [CO 2 ]e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under 350 μmol mol −1 day-time [CO 2 ], 900 μmol mol −1 at night reduced growth over a 4-week period by 9% ( P <0.05) and 1700 μmol mol −1 reduced it by 14% ( P <0.01)”
t0“Xanthium strumarium”
Claim · model-written summary
With daytime CO2 at 900, nighttime CO2 at 900 versus 350 increased growth by 17%.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Treatment
- 900e0
- Outcome
- growthe0
- Direction
- increasede0
- Value
- 17%e0
- Qualifier
- 900 μmol mol −1 day-time [CO 2 ]e0
- Comparator
- 350 μmol mol −1 [CO 2 ] at nighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“under 900 μmol mol −1 day-time [CO 2 ], 900 vs . 350 μmol mol −1 [CO 2 ] at night increased growth by 17% ( P <0.01)”
t0“Xanthium strumarium”
Claim · model-written summary
The authors interpret salt-increased respiration as having functional and functionless components.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Outcome
- Rde0
- Qualifier
- functional and an otiose (functionless) componente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there is both a functional and an otiose (functionless) component to Rd, which is increased by salt”
t0“Xanthium strumarium”
Claim · model-written summary
The authors infer that high nighttime CO2 suppresses functional respiration and reduces salt tolerance under low photosynthesis.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Outcome
- salt tolerancee0
- Qualifier
- high night-time [CO 2 ] partly suppresses functional Rde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under conditions of low photosynthesis (such as here, in the low day-time [CO 2 ] regime) the otiose component is small and high night-time [CO 2 ] partly suppresses functional Rd, thereby reducing salt tolerance”
t0“Xanthium strumarium”
Claim · model-written summary
Under high daytime CO2, the authors infer nighttime CO2 suppresses functionless respiration and increases growth.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Outcome
- growthe0
- Qualifier
- suppresses mainly the otiose component of respiratione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO 2 ] at night suppresses mainly the otiose component of respiration, thus increasing growth”
t0“Xanthium strumarium”
Claim · model-written summary
Further atmospheric CO2 elevation is projected to increase plant salt tolerance where water and sunlight are adequate.
- Taxon
- Xanthium strumariumXanthium strumariumt0
- Outcome
- plant salinity tolerancee0
- Direction
- increasee0
- Qualifier
- in regions of adequate water and sunlighte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in regions of adequate water and sunlight, the predicted further elevation of the world atmospheric [CO 2 ] may increase plant salinity tolerance”
t0“Xanthium strumarium”
The same questions in other papers
co2 · growth · Xanthium strumarium (cocklebur)Positive and negative results
11 papers in the same direction as this paper · 4 in the opposite direction
- no effect
- negative
- no effect
12 papers more in this group
See all 16 papers →salinity · growth · Xanthium strumarium (cocklebur)Results agree
1 paper in the same direction as this paper
- negative
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.