Abstract
Low, static concentrations of ammonium have less negative effects on nodulation of pea ( Pisum sativum L.) than nitrate and in some cases may actually stimulate nodulation. Two experiments were carried out to assess the effects of supplying both forms of mineral N, separately and in combination, on nodule initiation, nodule development, nodule distribution between primary and lateral (secondary) roots, tertiary root development, and N 2 fixation in pea. Pea plants were grown for up to 24 d after inoculation in hydroponic culture with no mineral N (zero N), NO 3 – (0.5 mmol·L –1 ), NH 4 + (0.5 mmol·L –1 ), or NO 3 – (0.25 mmol·L –1 ) plus NH 4 + (0.25 mmol·L –1 ). Concentrations of nitrate and ammonium were monitored on a daily basis and held relatively constant by continuous, automatic additions of stock solutions. Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium but had the lowest nodule DM and percentage of nitrogen derived from the atmosphere. Whole-plant nodulation (nodules per plant) and DM-specific nodulation (nodules·g –1 root DM) were 2.3- and 2.4-fold greater, respectively, in pea plants receiving NH 4 + at 0.5 mmol·L –1 than in those supplied with NO 3 – at 0.5 mmol·L –1 . The nodulation responses of plants receiving NO 3 – at 0.25 mmol·L –1 plus NH 4 + at 0.25 mmol·L –1 were more similar to those of plants receiving only nitrate than only ammonium, indicating that when both forms of mineral N are available to plants, nitrate has a predominant effect on the nodulation response. Assessment of the stage of development of nodule primordia and nodules during the time course of the experiments indicated that nitrate not only decreased the degree of nodule initiation but also the rate at which those nodules developed. Microscopic observations indicated that the more negative effects of the nitrate treatment on DM-specific nodulation as compared with the ammonium treatment were consistent on both the primary and lateral roots. Quantification of nodulation and tertiary root development on lateral roots indicated that the stimulating effects of ammonium were specific to nodulation; the effects on tertiary root development were different. The study demonstrates for the first time that when both forms of mineral N are available at equal concentrations, the nodulation response in pea is influenced more by nitrate than by ammonium and that the effects of nitrate and ammonium on tertiary root initiation and development are unlike those on nodulation.
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Claims 12
Claim · model-written summary
Combined nitrate and ammonium produced the most total pea dry mass.
- Taxon
- Pea
Lathyrus oleraceuse0 - Treatment
- combination of nitrate plus ammoniume0
- Outcome
- total dry mass (DM)e0
- Direction
- moste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium”
Claim · model-written summary
Combined nitrate and ammonium produced the most total pea nitrogen.
- Taxon
- PeaLathyrus oleraceuse0
- Treatment
- combination of nitrate plus ammoniume0
- Outcome
- total Ne0
- Direction
- moste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium”
Claim · model-written summary
Combined nitrate and ammonium gave the lowest pea nodule dry mass.
- Taxon
- PeaLathyrus oleraceuse0
- Treatment
- combination of nitrate plus ammoniume0
- Outcome
- nodule DMe0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium but had the lowest nodule DM and percentage of nitrogen derived from the atmosphere”
Claim · model-written summary
Combined nitrate and ammonium gave the lowest percentage of nitrogen derived from the atmosphere.
- Taxon
- PeaLathyrus oleraceuse0
- Treatment
- combination of nitrate plus ammoniume0
- Outcome
- percentage of nitrogen derived from the atmospheree0
- Direction
- loweste0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Pea plants accumulated the most total dry mass (DM) and total N when supplied with the combination of nitrate plus ammonium but had the lowest nodule DM and percentage of nitrogen derived from the atmosphere”
Claim · model-written summary
Ammonium at 0.5 mmol·L –1 yielded 2.3 fold more nodules per plant than nitrate at the same concentration.
- Taxon
- peaLathyrus oleraceuse0
- Treatment
- NH 4 + at 0.5 mmol·L –1e0
- Outcome
- Whole-plant nodulation (nodules per plant)e0
- Direction
- greatere0
- Value
- 2.3-e0
- Comparator
- NO 3 – at 0.5 mmol·L –1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Whole-plant nodulation (nodules per plant) and DM-specific nodulation (nodules·g –1 root DM) were 2.3- and 2.4-fold greater, respectively, in pea plants receiving NH 4 + at 0.5 mmol·L –1 than in those supplied with NO 3 – at 0.5 mmol·L –1”
Claim · model-written summary
Ammonium at 0.5 mmol·L –1 yielded 2.4 fold greater nodulation per root dry mass than nitrate.
- Taxon
- peaLathyrus oleraceuse0
- Treatment
- NH 4 + at 0.5 mmol·L –1e0
- Outcome
- DM-specific nodulation (nodules·g –1 root DM)e0
- Direction
- greatere0
- Value
- 2.4-folde0
- Comparator
- NO 3 – at 0.5 mmol·L –1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Whole-plant nodulation (nodules per plant) and DM-specific nodulation (nodules·g –1 root DM) were 2.3- and 2.4-fold greater, respectively, in pea plants receiving NH 4 + at 0.5 mmol·L –1 than in those supplied with NO 3 – at 0.5 mmol·L –1”
Claim · model-written summary
The combined nitrogen nodulation response resembled nitrate alone more than ammonium alone.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- NO 3 – at 0.25 mmol·L –1 plus NH 4 + at 0.25 mmol·L –1e0
- Outcome
- nodulation responsese0
- Direction
- more similare0
- Comparator
- only nitratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The nodulation responses of plants receiving NO 3 – at 0.25 mmol·L –1 plus NH 4 + at 0.25 mmol·L –1 were more similar to those of plants receiving only nitrate than only ammonium”
t0“pea”
Claim · model-written summary
Nitrate decreased pea nodule initiation.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- nitratee0
- Outcome
- degree of nodule initiatione0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate not only decreased the degree of nodule initiation but also the rate at which those nodules developed”
t0“pea”
Claim · model-written summary
Nitrate decreased pea nodule development rate.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- nitratee0
- Outcome
- rate at which those nodules developede0
- Direction
- decreasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate not only decreased the degree of nodule initiation but also the rate at which those nodules developed”
t0“pea”
Claim · model-written summary
Nitrate had a more negative effect on nodulation per root dry mass than ammonium in primary roots.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- primarye0
- Treatment
- nitrate treatmente0
- Outcome
- DM-specific nodulatione0
- Direction
- more negativee0
- Comparator
- ammonium treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“more negative effects of the nitrate treatment on DM-specific nodulation as compared with the ammonium treatment were consistent on both the primary and lateral roots”
t0“pea”
Claim · model-written summary
Nitrate had a more negative effect on nodulation per root dry mass than ammonium in lateral roots.
- Taxon
- peaLathyrus oleraceust0
- Organ / stage
- lateral rootse0
- Treatment
- nitrate treatmente0
- Outcome
- DM-specific nodulatione0
- Direction
- more negativee0
- Comparator
- ammonium treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“more negative effects of the nitrate treatment on DM-specific nodulation as compared with the ammonium treatment were consistent on both the primary and lateral roots”
t0“pea”
Claim · model-written summary
Ammonium stimulated nodulation specifically, with different effects on tertiary root development.
- Taxon
- peaLathyrus oleraceust0
- Treatment
- ammoniume0
- Outcome
- nodulatione0
- Direction
- stimulatinge0
- Qualifier
- effects on tertiary root development were differente0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“stimulating effects of ammonium were specific to nodulation; the effects on tertiary root development were different”
t0“pea”
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