Abstract
The effects of P deficiency on growth, N(2)-fixation and photosynthesis in white clover (Trifolium repens L.) plants were investigated using three contrasting relative addition rates of P, or following abrupt withdrawal of the P supply. Responses to a constant below-optimum P supply rate consisted of a decline in N(2)-fixation per unit root weight and a small reduction in the efficiency with which electrons were allocated to the reduction of N(2) in nodules. Abrupt removal of P arrested nodule growth and caused a substantial decline in nitrogenase activity per unit root weight, but not per unit nodule mass. Similarly, the rate of photosynthesis per unit leaf area was unaffected by abrupt P removal, whereas CO(2) acquisition for the plant as a whole decreased due to a decline in total leaf area, leaf area per unit leaf weight and utilization of incoming radiation. These changes followed the decline in tissue P concentrations. The ratio between CO(2)-fixation and N(2)-fixation was maintained under short-term P deprivation but increased under long-term low P supply, indicating a regulatory inhibition of nodule activity following morphological and growth adjustments. It is concluded that N(2)-fixation did not limit the growth of clover plants experiencing P deficiency. A low P status induced changes in the relative growth of roots, nodules and shoots rather than changes in N and/or C uptake rates per unit mass or area of these organs.
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Claims 12
Claim · model-written summary
A constant below-optimum P supply rate caused a decline in N2-fixation per unit root weight in white clover.
- Taxon
- white clover
Trifolium repense0 - Treatment
- constant below-optimum P supply ratee1
- Outcome
- N(2)-fixation per unit root weighte1
- Direction
- declinee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“constant below-optimum P supply rate consisted of a decline in N(2)-fixation per unit root weight”
Claim · model-written summary
A constant below-optimum P supply rate caused a small reduction in the efficiency with which electrons were allocated to N2 reduction in nodules of white clover.
- Taxon
- white cloverTrifolium repense0
- Treatment
- constant below-optimum P supply ratee1
- Outcome
- efficiency with which electrons were allocated to the reduction of N(2) in nodulese1
- Direction
- small reductione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“constant below-optimum P supply rate consisted of a decline in N(2)-fixation per unit root weight and a small reduction in the efficiency with which electrons were allocated to the reduction of N(2) in nodules”
Claim · model-written summary
Abrupt removal of P arrested nodule growth in white clover.
- Taxon
- white cloverTrifolium repense0
- Treatment
- Abrupt removal of Pe1
- Outcome
- nodule growthe1
- Direction
- arrestede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“Abrupt removal of P arrested nodule growth”
Claim · model-written summary
Abrupt removal of P caused a substantial decline in nitrogenase activity per unit root weight in white clover.
- Taxon
- white cloverTrifolium repense0
- Treatment
- Abrupt removal of Pe1
- Outcome
- nitrogenase activity per unit root weighte1
- Direction
- substantial declinee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“Abrupt removal of P arrested nodule growth and caused a substantial decline in nitrogenase activity per unit root weight”
Claim · model-written summary
Abrupt removal of P did not decrease nitrogenase activity per unit nodule mass in white clover.
- Taxon
- white cloverTrifolium repense0
- Treatment
- Abrupt removal of Pe1
- Outcome
- nitrogenase activity per unit root weight, but not per unit nodule masse1
- Direction
- no_changeinferrede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“Abrupt removal of P arrested nodule growth and caused a substantial decline in nitrogenase activity per unit root weight, but not per unit nodule mass”
Claim · model-written summary
The rate of photosynthesis per unit leaf area of white clover was unaffected by abrupt P removal.
- Taxon
- white cloverTrifolium repense0
- Treatment
- abrupt P removale1
- Outcome
- rate of photosynthesis per unit leaf areae1
- Direction
- unaffectede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“the rate of photosynthesis per unit leaf area was unaffected by abrupt P removal”
Claim · model-written summary
CO2 acquisition for the whole white clover plant decreased after abrupt P removal.
- Taxon
- white cloverTrifolium repense0
- Treatment
- abrupt P removale1
- Outcome
- CO(2) acquisition for the plant as a wholee2
- Direction
- decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“abrupt P removal”
e2“CO(2) acquisition for the plant as a whole decreased”
Claim · model-written summary
The decrease in whole-plant CO2 acquisition was attributed to declines in total leaf area, leaf area per unit leaf weight and utilization of incoming radiation.
- Taxon
- white cloverTrifolium repense0
- Outcome
- CO(2) acquisition for the plant as a whole decreasede1
- Qualifier
- decline in total leaf area, leaf area per unit leaf weight and utilization of incoming radiatione1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“CO(2) acquisition for the plant as a whole decreased due to a decline in total leaf area, leaf area per unit leaf weight and utilization of incoming radiation”
Claim · model-written summary
The ratio between CO2 fixation and N2 fixation of white clover was maintained under short-term P deprivation.
- Taxon
- white cloverTrifolium repense0
- Treatment
- short-term P deprivatione1
- Outcome
- ratio between CO(2)-fixation and N(2)-fixatione1
- Direction
- maintainede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“The ratio between CO(2)-fixation and N(2)-fixation was maintained under short-term P deprivation”
Claim · model-written summary
The ratio between CO2 fixation and N2 fixation of white clover increased under long-term low P supply, which the authors interpret as regulatory inhibition of nodule activity.
- Taxon
- white cloverTrifolium repense0
- Treatment
- long-term low P supplye1
- Outcome
- ratio between CO(2)-fixation and N(2)-fixatione1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“The ratio between CO(2)-fixation and N(2)-fixation was maintained under short-term P deprivation but increased under long-term low P supply”
Claim · model-written summary
The authors conclude that N2 fixation did not limit the growth of clover plants experiencing P deficiency.
TrifoliumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“N(2)-fixation did not limit the growth of clover plants experiencing P deficiency”
Claim · model-written summary
A low P status induced changes in the relative growth of roots, nodules and shoots of white clover rather than changes in N and/or C uptake rates per unit mass or area of these organs.
- Taxon
- white cloverTrifolium repense0
- Treatment
- low P statuse1
- Outcome
- relative growth of roots, nodules and shootse1
- Direction
- changese1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“white clover (Trifolium repens L.)”
e1“A low P status induced changes in the relative growth of roots, nodules and shoots”
The same questions in other papers
phosphorus · symbiosis · Trifolium repens (white clover)Positive and negative results
6 papers in the same direction as this paper · 2 in the opposite direction
- positive
- no effect
- no effect
5 papers more in this group
See all 9 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.