Abstract
The effect of ammonium present in the induction medium toghether with nitrate on the activity of nitrate reductase (NR), nitrite reductase (NiR), glutamic acid dehydrogenase (GDH) and absorption and accumulation of NO3- in cucumber seedlings were investigated. Maximum NR and NiR activity in the cotyledons was observed when seedlings were supplied with KNO3 as the sole source of nitrogen. When plants were supplied with NH4NO3 the presence of NH4+ in the induction medium repressed by about 50 per cent the activity of both reductases in the cotyledons. Addition of K+ to this medium abolished completely the inhibitory effect of NH4+. The effect of K+ cannot be replaced by that Na+ ions. On the other hand, ammonium has no effect on the level of NR activity in roots, while NiR was almost completely repressed. Under the experimental conditions ammonium, in the presence of nitrates, decreased the activity of GDH, but this diminution did not occur when the plants were supplied with K+ simultaneously. It has found that NH4+ ions reduced NO3- absorption but at the same time, the ratio of NO3- absorbed to that reduced was increased more than twice. The presumable mechanism of these phenomena is discussed.
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Claims 10
Claim · model-written summary
KNO3 as sole nitrogen source gave maximum cotyledon NR and NiR activity.
- Taxon
- cucumber seedlings
Cucumis sativust0 - Organ / stage
- cotyledonse0
- Treatment
- KNO3 as the sole source of nitrogene0
- Outcome
- NR and NiR activitye0
- Direction
- Maximume0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“Maximum NR and NiR activity in the cotyledons was observed when seedlings were supplied with KNO3 as the sole source of nitrogen”
Claim · model-written summary
NH4NO3 repressed cotyledon reductase activities by about 50 percent.
- Taxon
- cucumber seedlingsCucumis sativust0
- Organ / stage
- cotyledonse0
- Treatment
- NH4NO3e0
- Outcome
- activity of both reductases in the cotyledonse0
- Direction
- repressede0
- Value
- about 50 per cente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“When plants were supplied with NH4NO3 the presence of NH4+ in the induction medium repressed by about 50 per cent the activity of both reductases in the cotyledons”
Claim · model-written summary
Added potassium completely abolished ammonium inhibition.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- Addition of K+e0
- Outcome
- inhibitory effect of NH4+e0
- Direction
- abolished completelye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“Addition of K+ to this medium abolished completely the inhibitory effect of NH4+”
Claim · model-written summary
Sodium ions did not replace the effect of potassium ions.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- Na+ ionse0
- Outcome
- effect of K+e0
- Direction
- cannot be replacede0
- Comparator
- K+e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“The effect of K+ cannot be replaced by that Na+ ions”
Claim · model-written summary
Ammonium had no effect on root NR activity.
- Taxon
- cucumber seedlingsCucumis sativust0
- Organ / stage
- rootse0
- Treatment
- ammoniume0
- Outcome
- NR activity in rootse0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“ammonium has no effect on the level of NR activity in roots”
Claim · model-written summary
Ammonium almost completely repressed root NiR activity.
- Taxon
- cucumber seedlingsCucumis sativust0
- Organ / stage
- rootse0
- Treatment
- ammoniume0
- Outcome
- NiRe0
- Direction
- almost completely repressede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“ammonium has no effect on the level of NR activity in roots, while NiR was almost completely repressed”
Claim · model-written summary
Ammonium with nitrate decreased GDH activity.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- ammonium, in the presence of nitratese0
- Outcome
- activity of GDHe0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“ammonium, in the presence of nitrates, decreased the activity of GDH”
Claim · model-written summary
Simultaneous potassium supply prevented the ammonium-associated GDH decrease.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- K+e0
- Outcome
- activity of GDHe1
- Direction
- did not occure0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“this diminution did not occur when the plants were supplied with K+ simultaneously”
e1“decreased the activity of GDH”
Claim · model-written summary
Ammonium ions reduced nitrate absorption.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- NH4+ ionse0
- Outcome
- NO3- absorptione0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“NH4+ ions reduced NO3- absorption”
Claim · model-written summary
Ammonium more than doubled the ratio of nitrate absorbed to nitrate reduced.
- Taxon
- cucumber seedlingsCucumis sativust0
- Treatment
- NH4+ ionse1
- Outcome
- ratio of NO3- absorbed to that reducede0
- Direction
- increasede0
- Value
- more than twicee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cucumber seedlings”
e0“the ratio of NO3- absorbed to that reduced was increased more than twice”
e1“NH4+ ions reduced NO3- absorption”
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See all 10 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.