Abstract
The effect of ambient ammonium (0.5 millimolar [(14)NH(4)](2)SO(4)) added to a nutrient solution containing 1.0 millimolar K(15)NO(3), 99 atom per cent (15)N, upon [(15)N]nitrate assimilation and utilization of previously accumulated [(14)N]nitrate was investigated. Corn seedlings, 5-day-old dark-grown decapitated (experiment I) and 10-day-old light-grown intact (experiment II), which had previously been grown on K(14)NO(3) nutrient solution, were used. In both experiments, the presence of ambient ammonium decreased [(15)N]nitrate influx (20% after 6 hours) without significantly affecting the efflux of previously accumulated [(14)N]nitrate. In experiment I, relative reduction of [(15)N]nitrate (reduction as a percentage of influx) was inhibited more than was [(15)N]nitrate influx. Nevertheless, in experiment I, where all reduction could be assigned to the root system, the absolute inhibition of reduction during the 12 hours (13 micromoles/root) was less than the absolute inhibition in influx (24 micromoles/root). The data suggest that the influence of ammonium on [(15)N]nitrate influx could not be totally accounted for by the decrease in the potential driving force which resulted from restricted reduction; an additional impact on the influx process is indicated. Reduction of [(15)N]nitrate in experiment II after 6 hours accounted for 30 and 18% of the tissue excess (15)N in the control and ammonium treatments, respectively. Relative distribution of (15)N between roots and exudate (experiment I), or between roots and shoots (experiment II) was not affected by ammonium. On the other hand, the accumulation of [(15)N]nitrate in roots, shoots, and xylem exudate was enhanced by ammonium treatment compared to the control, whereas the accumulation of reduced (15)N was inhibited.
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Claims 11
Claim · model-written summary
Ambient ammonium decreased labeled nitrate influx by 20% after six hours.
- Taxon
- Corn
Zea mays subsp. mayst0 - Treatment
- ambient ammoniume0
- Outcome
- [(15)N]nitrate influxe0
- Direction
- decreasede0
- Value
- 20%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the presence of ambient ammonium decreased [(15)N]nitrate influx (20% after 6 hours)”
t0“Corn Seedlings”
Claim · model-written summary
Ambient ammonium did not significantly affect efflux of previously accumulated nitrate.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ambient ammoniume1
- Outcome
- efflux of previously accumulated [(14)N]nitratee0
- Direction
- without significantly affectinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“without significantly affecting the efflux of previously accumulated [(14)N]nitrate”
e1“the presence of ambient ammonium”
t0“Corn Seedlings”
Claim · model-written summary
In experiment I, ammonium inhibited relative nitrate reduction more than nitrate influx.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ambient ammoniume1
- Outcome
- relative reduction of [(15)N]nitratee0
- Direction
- inhibited moree0
- Comparator
- [(15)N]nitrate influxe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“relative reduction of [(15)N]nitrate (reduction as a percentage of influx) was inhibited more than was [(15)N]nitrate influx”
e1“presence of ambient ammonium”
t0“Corn Seedlings”
Claim · model-written summary
In experiment I, absolute reduction inhibition was 13 micromoles per root, less than influx inhibition.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ambient ammoniume1
- Outcome
- absolute inhibition of reductione0
- Direction
- less thane0
- Value
- 13 micromoles/roote0
- Comparator
- influxe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the absolute inhibition of reduction during the 12 hours (13 micromoles/root) was less than the absolute inhibition in influx (24 micromoles/root)”
e1“presence of ambient ammonium”
t0“Corn Seedlings”
Claim · model-written summary
In experiment I, absolute nitrate influx inhibition was 24 micromoles per root.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ambient ammoniume1
- Outcome
- influxe0
- Direction
- inhibitione0
- Value
- 24 micromoles/roote0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“absolute inhibition in influx (24 micromoles/root)”
e1“presence of ambient ammonium”
t0“Corn Seedlings”
Claim · model-written summary
Restricted reduction alone could not fully account for ammonium effects on nitrate influx.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ammoniume0
- Outcome
- [(15)N]nitrate influxe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the influence of ammonium on [(15)N]nitrate influx could not be totally accounted for by the decrease in the potential driving force which resulted from restricted reduction; an additional impact on the influx process is indicated”
t0“Corn Seedlings”
Claim · model-written summary
In experiment II, reduced nitrate accounted for 30% of tissue excess nitrogen in controls.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- Reduction of [(15)N]nitratee0
- Value
- 30e0
- Comparator
- controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduction of [(15)N]nitrate in experiment II after 6 hours accounted for 30 and 18% of the tissue excess (15)N in the control and ammonium treatments, respectively”
t0“Corn Seedlings”
Claim · model-written summary
In experiment II, reduced nitrate accounted for 18% of tissue excess nitrogen under ammonium.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ammonium treatmentse0
- Outcome
- Reduction of [(15)N]nitratee0
- Value
- 18%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Reduction of [(15)N]nitrate in experiment II after 6 hours accounted for 30 and 18% of the tissue excess (15)N in the control and ammonium treatments, respectively”
t0“Corn Seedlings”
Claim · model-written summary
Ammonium did not affect relative nitrogen distribution between plant compartments.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ammoniume0
- Outcome
- Relative distribution of (15)Ne0
- Direction
- not affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Relative distribution of (15)N between roots and exudate (experiment I), or between roots and shoots (experiment II) was not affected by ammonium”
t0“Corn Seedlings”
Claim · model-written summary
Ammonium enhanced nitrate accumulation in roots, shoots and xylem exudate.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ammonium treatmente0
- Outcome
- accumulation of [(15)N]nitrate in roots, shoots, and xylem exudatee0
- Direction
- enhancede0
- Comparator
- the controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the accumulation of [(15)N]nitrate in roots, shoots, and xylem exudate was enhanced by ammonium treatment compared to the control”
t0“Corn Seedlings”
Claim · model-written summary
Ammonium inhibited accumulation of reduced nitrogen.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- ammonium treatmente1
- Outcome
- accumulation of reduced (15)Ne0
- Direction
- inhibitede0
- Comparator
- the controle1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the accumulation of reduced (15)N was inhibited”
e1“ammonium treatment compared to the control”
t0“Corn Seedlings”
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