Abstract
Abstract At very low concentrations of Ca 2+ in solution both H + and Cu 2+ retarded Zn 2+ absorption through two distinct effects—toxicity and inhibition. Concentrations of 350µ M Ca 2+ overcame toxic effects of H + at pH 3 but even 500µ M Ca 2+ did not prevent toxicity of Cu 2+ at 10µ M . At Ca 2+ concentrations commonly encountered in soil solutions no toxicities appeared. Copper inhibited Zn 2+ absorption strongly and competitively, Co 2+ competitively but weakly, and Mn 2+ and Fe 2+ had no effect. Also, Ca 2+ had no effect on Cu 2+ inhibition. Increasing H + concentration from pH 7 to 3 in the presence of 350µ M , 10m M , or 50m M Ca 2+ severely inhibited Zn 2+ absorption. Hydrogen ions inhibited Zn 2+ absorption by two mechanisms—one Ca 2+ ‐sensitive, the other Ca 2+ ‐insensitive. The Ca 2+ ‐sensitive mechanism only operated at very low Ca 2+ or under very acid conditions. At the usual H + and Ca 2+ concentrations of soil solutions, H + inhibited Zn 2+ absorption only by the Ca 2+ insensitive mechanism; in this mechanism H + was non‐competitive with Zn 2+ . In soils the effects of Ca 2+ , Cu 2+ , and of H + would be additive. However the effects of Cu 2+ and especially of H + on soil chemical reactions may operate in the opposite direction to their effects on Zn 2+ absorption. More information is needed on the behavior of chelating compounds before the effects of Cu 2+ on Zn 2+ absorption from soils can be assessed.
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Claims 14
Claim · model-written summary
At low calcium, hydrogen and copper ions retarded zinc absorption through toxicity and inhibition.
- Taxon
- Wheat Seedlings
Triticum aestivumt0 - Treatment
- H + and Cu 2+e0
- Outcome
- Zn 2+ absorptione0
- Direction
- retardede0
- Qualifier
- At very low concentrations of Ca 2+e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At very low concentrations of Ca 2+ in solution both H + and Cu 2+ retarded Zn 2+ absorption through two distinct effects—toxicity and inhibition”
t0“Wheat Seedlings”
Claim · model-written summary
Calcium at 350µ M overcame hydrogen toxicity at pH 3.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- 350µ M Ca 2+e0
- Outcome
- toxic effects of H +e0
- Direction
- overcamee0
- Qualifier
- pH 3e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Concentrations of 350µ M Ca 2+ overcame toxic effects of H + at pH 3”
t0“Wheat Seedlings”
Claim · model-written summary
Calcium at 500µ M did not prevent copper toxicity at 10µ M.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- 500µ M Ca 2+e0
- Outcome
- toxicity of Cu 2+e0
- Direction
- did not prevente0
- Qualifier
- at 10µ Me0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“even 500µ M Ca 2+ did not prevent toxicity of Cu 2+ at 10µ M”
t0“Wheat Seedlings”
Claim · model-written summary
No ion toxicities appeared at calcium concentrations common in soil solutions.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Outcome
- no toxicities appearede0
- Qualifier
- At Ca 2+ concentrations commonly encountered in soil solutionse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At Ca 2+ concentrations commonly encountered in soil solutions no toxicities appeared”
t0“Wheat Seedlings”
Claim · model-written summary
Copper strongly and competitively inhibited zinc absorption.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- Coppere0
- Outcome
- Zn 2+ absorptione0
- Direction
- inhibitede0
- Qualifier
- strongly and competitivelye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Copper inhibited Zn 2+ absorption strongly and competitively”
t0“Wheat Seedlings”
Claim · model-written summary
Cobalt weakly and competitively inhibited zinc absorption.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- Co 2+e0
- Outcome
- Zn 2+ absorptione1
- Qualifier
- competitively but weaklye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Co 2+ competitively but weakly”
e1“Copper inhibited Zn 2+ absorption strongly and competitively, Co 2+ competitively but weakly”
t0“Wheat Seedlings”
Claim · model-written summary
Manganese and iron had no effect on zinc absorption.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- Mn 2+ and Fe 2+e0
- Outcome
- Zn 2+ absorptione1
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Mn 2+ and Fe 2+ had no effect”
e1“Copper inhibited Zn 2+ absorption strongly and competitively, Co 2+ competitively but weakly, and Mn 2+ and Fe 2+ had no effect”
t0“Wheat Seedlings”
Claim · model-written summary
Calcium had no effect on copper inhibition.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- Ca 2+e0
- Outcome
- Cu 2+ inhibitione0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Ca 2+ had no effect on Cu 2+ inhibition”
t0“Wheat Seedlings”
Claim · model-written summary
Increasing hydrogen ion concentration from pH 7 to 3 severely inhibited zinc absorption at three calcium concentrations.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Treatment
- Increasing H + concentration from pH 7 to 3e0
- Outcome
- Zn 2+ absorptione0
- Direction
- inhibitede0
- Qualifier
- 350µ M , 10m M , or 50m M Ca 2+e0
- Comparator
- pH 7e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increasing H + concentration from pH 7 to 3 in the presence of 350µ M , 10m M , or 50m M Ca 2+ severely inhibited Zn 2+ absorption”
t0“Wheat Seedlings”
Claim · model-written summary
Hydrogen ion inhibition of zinc absorption had calcium sensitive and insensitive mechanisms.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Outcome
- Zn 2+ absorptione0
- Qualifier
- one Ca 2+ ‐sensitive, the other Ca 2+ ‐insensitivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Hydrogen ions inhibited Zn 2+ absorption by two mechanisms—one Ca 2+ ‐sensitive, the other Ca 2+ ‐insensitive”
t0“Wheat Seedlings”
Claim · model-written summary
The calcium sensitive mechanism operated only at very low calcium or highly acidic conditions.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Outcome
- Ca 2+ ‐sensitive mechanism only operatede0
- Qualifier
- at very low Ca 2+ or under very acid conditionse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Ca 2+ ‐sensitive mechanism only operated at very low Ca 2+ or under very acid conditions”
t0“Wheat Seedlings”
Claim · model-written summary
At usual soil-solution ion concentrations, hydrogen inhibited zinc absorption only by a calcium insensitive, noncompetitive mechanism.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Outcome
- Zn 2+ absorptione0
- Direction
- inhibitede0
- Qualifier
- Ca 2+ insensitive mechanisme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the usual H + and Ca 2+ concentrations of soil solutions, H + inhibited Zn 2+ absorption only by the Ca 2+ insensitive mechanism; in this mechanism H + was non‐competitive with Zn 2+”
t0“Wheat Seedlings”
Claim · model-written summary
The effects of calcium, copper and hydrogen on zinc absorption in soils were predicted to be additive.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Outcome
- effects of Ca 2+ , Cu 2+ , and of H + would be additivee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In soils the effects of Ca 2+ , Cu 2+ , and of H + would be additive”
e1“Zn 2+ absorption from soils”
t0“Wheat Seedlings”
Claim · model-written summary
Copper and hydrogen effects on soil chemistry may oppose their effects on zinc absorption.
- Taxon
- Wheat SeedlingsTriticum aestivumt0
- Outcome
- Zn 2+ absorptione0
- Qualifier
- soil chemical reactions may operate in the opposite directione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effects of Cu 2+ and especially of H + on soil chemical reactions may operate in the opposite direction to their effects on Zn 2+ absorption”
t0“Wheat Seedlings”
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