Abstract
Abstract The fate of nitrate and nitrogen‐15 was followed during the apparent induction phase (6h) for nitrate uptake by N‐depleted dwarf bean ( Phaseolus vulgaris L. ev. Witte Krombek). Experiments were done with intact plants and with detached root systems. Qualitatively and quantitatively, xylem exudation from detached roots was a bad estimate of the export of NO − 3 or NO − 3 ‐ 15 N from roots of intact plants. In vivo nitrate reductase activity (NRA) agreed well with in situ reduction, calculated as the difference between uptake and accumulation in whole plants, provided NRA was assayed with merely endogenous nitrate as substrate (‘actual’ NRA). The majority (75%) of the entering nitrate remained unmetabolized. Both nitrate reduction and nitrate accumulation occurred predominantly in the root system. Some (< 25%) of the root‐reduced nitrate‐N was translocated to the shoot. Nitrate uptake occurred against the concentration gradient between medium and root cells, and probably against the gradient of the electro‐chemical potential of nitrate. Part of the energy expended for NO − 3 absorption came from the tops, since decapitation and ringing at the stem base restricted nitrate uptake.
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Claims 10
Claim · model-written summary
Detached-root xylem exudation poorly estimated nitrate export from intact dwarf bean roots.
Verbatim
e0“xylem exudation from detached roots was a bad estimate of the export of NO − 3 or NO − 3 ‐ 15 N from roots of intact plants.”
t0“dwarf bean”
Claim · model-written summary
Actual in vivo nitrate reductase activity agreed with in situ reduction calculated from whole-plant uptake and accumulation.
Verbatim
e0“In vivo nitrate reductase activity (NRA) agreed well with in situ reduction, calculated as the difference between uptake and accumulation in whole plants, provided NRA was assayed with merely endogenous nitrate as substrate (‘actual’ NRA).”
t0“dwarf bean”
Claim · model-written summary
Most entering nitrate remained unmetabolized in dwarf bean plants.
Verbatim
e0“The majority (75%) of the entering nitrate remained unmetabolized.”
t0“dwarf bean”
Claim · model-written summary
Nitrate reduction occurred predominantly in the dwarf bean root system.
Verbatim
e0“Both nitrate reduction and nitrate accumulation occurred predominantly in the root system.”
t0“dwarf bean”
Claim · model-written summary
Nitrate accumulation occurred predominantly in the dwarf bean root system.
Verbatim
e0“Both nitrate reduction and nitrate accumulation occurred predominantly in the root system.”
t0“dwarf bean”
Claim · model-written summary
Less than 25% of root-reduced nitrate nitrogen was transported to the dwarf bean shoot.
Verbatim
e0“Some (< 25%) of the root‐reduced nitrate‐N was translocated to the shoot.”
t0“dwarf bean”
Claim · model-written summary
Dwarf bean nitrate uptake occurred against the concentration gradient between medium and root cells.
Verbatim
e0“Nitrate uptake occurred against the concentration gradient between medium and root cells”
t0“dwarf bean”
Claim · model-written summary
Dwarf bean nitrate uptake probably occurred against the electrochemical potential gradient.
Verbatim
e0“and probably against the gradient of the electro‐chemical potential of nitrate.”
t0“dwarf bean”
Claim · model-written summary
Decapitation restricted dwarf bean nitrate uptake.
Not reportedComparator
Verbatim
e0“decapitation and ringing at the stem base restricted nitrate uptake.”
t0“dwarf bean”
Claim · model-written summary
Ringing at the stem base restricted dwarf bean nitrate uptake.
Not reportedComparator
Verbatim
e0“decapitation and ringing at the stem base restricted nitrate uptake.”
t0“dwarf bean”
The same questions in other papers
pruning · nutrient: content · Phaseolus vulgaris (common bean)Positive and negative results
3 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- negative
1 paper more in this group
See all 5 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.