Abstract
The effects of Cu, Cd, and Pb toxicity on photosynthesis in cucumber leaves (Cucumis sativus L.) were studied by the measurements of gas exchange characteristics, chlorophyll (Chl) fluorescence parameters, and Chl content. Concentrations of metals in sequence of 20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50-60 % after 10 d of treatment whereas 50 μM of Cu decreased it to 30 %. The content of Cd in leaves of plants treated with 50 μM Cd was three times higher than the contents of Cu and Pb after plant treatment with 50 μM Cu or 1 000 μM Pb. Hence Cd was transported to leaves much better than Cu and Pb. Nevertheless, the net photosynthetic rate and stomatal conductance in leaves treated with 50 μM Cu or Cd were similarly reduced. Thus, Cu was more toxic than Cd and Pb for photosynthesis in cucumber leaves. None of the investigated metals decreased internal CO2 concentrations. Also the effect of metals on potential efficiency of photosystem 2, PS2 (Fv/Fm) was negligible. The metal dependent reduction of PS2 quantum efficiency (ΦPS2) after plant adaptation in actinic irradiation was more noticeable. This could imply that reduced demand for ATP and NADPH in a dark phase of photosynthesis caused a down-regulation of PS2 photochemistry. Furthermore, in leaves of metal-treated plants the decrease in water percentage as well as lower contents of Chl and Fe were observed. Thus photosynthesis is not the main limiting factor for cucumber growth under Cu, Cd, or Pb stress.
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Claims 17
Claim · model-written summary
20 μM Cu reduced cucumber dry mass to 50-60 % after 10 days.
- Taxon
- cucumber
Cucumis sativust0 - Treatment
- 20 μM Cue0
- Outcome
- plant dry masse0
- Direction
- decreasede0
- Value
- 50-60 %e0
- Qualifier
- after 10 d of treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50-60 % after 10 d of treatment”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
20 and 50 μM Cd reduced cucumber dry mass to 50-60 % after 10 days.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 20 and 50 μM Cde0
- Outcome
- plant dry masse0
- Direction
- decreasede0
- Value
- 50-60 %e0
- Qualifier
- after 10 d of treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50-60 % after 10 d of treatment”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
50 μM Cd reduced cucumber dry mass to 50-60 % after 10 days.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 50 μM Cde0
- Outcome
- plant dry masse0
- Direction
- decreasede0
- Value
- 50-60 %e0
- Qualifier
- after 10 d of treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50-60 % after 10 d of treatment”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
1 000 μM Pb reduced cucumber dry mass to 50-60 % after 10 days.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 1 000 μM Pbe0
- Outcome
- plant dry masse0
- Direction
- decreasede0
- Value
- 50-60 %e0
- Qualifier
- after 10 d of treatmente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50-60 % after 10 d of treatment”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
50 μM Cu reduced cucumber dry mass to 30 %.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 50 μM of Cue0
- Outcome
- plant dry masse1
- Direction
- decreasede0
- Value
- 30 %e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“50 μM of Cu decreased it to 30 %”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
e1“20 μM Cu, 20 and 50 μM Cd, and 1 000 μM Pb decreased the plant dry mass to 50-60 % after 10 d of treatment”
Claim · model-written summary
Leaf Cd content after 50 μM Cd treatment was three times Cu content after 50 μM Cu treatment.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 50 μM Cde0
- Outcome
- content of Cd in leavese0
- Direction
- highere0
- Value
- three timese0
- Comparator
- 50 μM Cue0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The content of Cd in leaves of plants treated with 50 μM Cd was three times higher than the contents of Cu and Pb after plant treatment with 50 μM Cu or 1 000 μM Pb”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Leaf Cd content after 50 μM Cd treatment was three times Pb content after 1 000 μM Pb treatment.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 50 μM Cde0
- Outcome
- content of Cd in leavese0
- Direction
- highere0
- Value
- three timese0
- Comparator
- 1 000 μM Pbe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The content of Cd in leaves of plants treated with 50 μM Cd was three times higher than the contents of Cu and Pb after plant treatment with 50 μM Cu or 1 000 μM Pb”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
50 μM Cu reduced net photosynthetic rate in cucumber leaves.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 50 μM Cue0
- Outcome
- net photosynthetic ratee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the net photosynthetic rate and stomatal conductance in leaves treated with 50 μM Cu or Cd were similarly reduced”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
50 μM Cu reduced stomatal conductance in cucumber leaves.
- Taxon
- cucumberCucumis sativust0
- Treatment
- 50 μM Cue0
- Outcome
- stomatal conductancee0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the net photosynthetic rate and stomatal conductance in leaves treated with 50 μM Cu or Cd were similarly reduced”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Cu was more toxic to cucumber photosynthesis than Cd and Pb.
- Taxon
- cucumberCucumis sativust0
- Outcome
- photosynthesis in cucumber leavese0
- Direction
- more toxice0
- Comparator
- Cd and Pbe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Cu was more toxic than Cd and Pb for photosynthesis in cucumber leaves”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
None of the tested metals lowered internal CO2 concentration.
- Taxon
- cucumberCucumis sativust0
- Treatment
- investigated metalse0
- Outcome
- internal CO2 concentrationse0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“None of the investigated metals decreased internal CO2 concentrations”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Metals had negligible effect on potential PS2 efficiency.
- Taxon
- cucumberCucumis sativust0
- Treatment
- metalse0
- Outcome
- potential efficiency of photosystem 2e0
- Direction
- negligiblee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effect of metals on potential efficiency of photosystem 2, PS2 (Fv/Fm) was negligible”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Metal treatment reduced PS2 quantum efficiency after actinic irradiation adaptation.
- Taxon
- cucumberCucumis sativust0
- Treatment
- metale0
- Outcome
- PS2 quantum efficiencye0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The metal dependent reduction of PS2 quantum efficiency (ΦPS2) after plant adaptation in actinic irradiation was more noticeable”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Metal-treated leaves had lower water percentage.
- Taxon
- cucumberCucumis sativust0
- Treatment
- metal-treatede0
- Outcome
- water percentagee0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in leaves of metal-treated plants the decrease in water percentage as well as lower contents of Chl and Fe were observed”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Metal-treated leaves had lower contents of Chl.
- Taxon
- cucumberCucumis sativust0
- Treatment
- metal-treatede0
- Outcome
- contents of Chle0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in leaves of metal-treated plants the decrease in water percentage as well as lower contents of Chl and Fe were observed”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
Metal-treated leaves had lower Fe.
- Taxon
- cucumberCucumis sativust0
- Treatment
- metal-treatede0
- Outcome
- Fee0
- Direction
- lowere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“in leaves of metal-treated plants the decrease in water percentage as well as lower contents of Chl and Fe were observed”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
Claim · model-written summary
The authors conclude photosynthesis is not the main growth limitation under Cu, Cd or Pb stress.
- Taxon
- cucumberCucumis sativust0
- Outcome
- cucumber growthe0
- Qualifier
- photosynthesis is not the main limiting factore0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“photosynthesis is not the main limiting factor for cucumber growth under Cu, Cd, or Pb stress”
t0“Changes of photosynthetic parameters in cucumber leaves under Cu, Cd, and Pb stress”
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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.