Abstract
ABSTRACT Phosphorus (P) deficiency reduces forage yield and stand persistence of alfalfa (Medicago sativa L.). The objective of this study was to determine the influence of P nutrition and defoliation on alfalfa shoot growth, root carbohydrate and protein metabolism, and steady-state mRNA levels for high-affinity P transporters. In a greenhouse study, P-deprived plants were provided with 0, 0.25, 2, and 6 mM P beginning 7 d before shoot removal. Plants were sampled immediately (day -7) on days -5, -2, 0 (day of shoot removal), and on days 1, 2, 6, and 9 post-shoot removal. Addition of P to P-deficient plants stimulated growth of shoots but not roots. Taproot bark sugar concentrations were reduced significantly in cut plants at any rate of P, whereas only the 6 mM P treatment reduced taproot wood sugar concentrations in uncut plants. There was a significant defoliation-induced decline in both wood and bark sugar and amino-acid concentration that was enhanced at high P rates. Low P reduced utilization of starch and protein reserves in taproots. Transcripts for a high-affinity P transporter were not detected in any root or shoot tissue assayed, irrespective of defoliation or P treatment. The uncertain relationship between P availability and P-transporter transcript abundance in our greenhouse-grown plants requires additional investigation.
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Claims 10
Claim · model-written summary
Adding phosphorus to deficient alfalfa stimulated shoot growth.
- Taxon
- Alfalfa
Medicago sativat0 - Treatment
- Addition of Pe0
- Outcome
- growth of shootse0
- Direction
- stimulatede0
- Comparator
- P-deficient plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Addition of P to P-deficient plants stimulated growth of shoots but not roots.”
t0“Alfalfa”
Claim · model-written summary
Adding phosphorus to deficient alfalfa did not stimulate root growth.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- Addition of Pe0
- Outcome
- rootse0
- Direction
- note0
- Comparator
- P-deficient plantse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Addition of P to P-deficient plants stimulated growth of shoots but not roots.”
t0“Alfalfa”
Claim · model-written summary
Cutting reduced taproot bark sugar concentrations at every phosphorus rate.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- cut plantse0
- Outcome
- Taproot bark sugar concentrationse0
- Direction
- reducede0
- Qualifier
- at any rate of Pe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Taproot bark sugar concentrations were reduced significantly in cut plants at any rate of P”
t0“Alfalfa”
Claim · model-written summary
The 6 mM phosphorus treatment reduced taproot wood sugar in uncut plants.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- 6 mM P treatmente0
- Outcome
- taproot wood sugar concentrationse0
- Direction
- reducede0
- Qualifier
- uncut plantse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“only the 6 mM P treatment reduced taproot wood sugar concentrations in uncut plants.”
t0“Alfalfa”
Claim · model-written summary
Defoliation decreased taproot wood sugar concentration, more strongly at high phosphorus rates.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- defoliatione0
- Outcome
- woode0
- Direction
- declinee0
- Qualifier
- enhanced at high P ratese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a significant defoliation-induced decline in both wood and bark sugar and amino-acid concentration that was enhanced at high P rates.”
t0“Alfalfa”
Claim · model-written summary
Defoliation decreased taproot bark sugar concentration, more strongly at high phosphorus rates.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- defoliatione0
- Outcome
- bark sugare0
- Direction
- declinee0
- Qualifier
- enhanced at high P ratese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a significant defoliation-induced decline in both wood and bark sugar and amino-acid concentration that was enhanced at high P rates.”
t0“Alfalfa”
Claim · model-written summary
Defoliation decreased taproot amino acid concentration, more strongly at high phosphorus rates.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- defoliatione0
- Outcome
- amino-acid concentratione0
- Direction
- declinee0
- Qualifier
- enhanced at high P ratese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a significant defoliation-induced decline in both wood and bark sugar and amino-acid concentration that was enhanced at high P rates.”
t0“Alfalfa”
Claim · model-written summary
Low phosphorus reduced use of taproot starch reserves.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- Low Pe0
- Outcome
- utilization of starche0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low P reduced utilization of starch and protein reserves in taproots.”
t0“Alfalfa”
Claim · model-written summary
Low phosphorus reduced use of taproot protein reserves.
- Taxon
- AlfalfaMedicago sativat0
- Treatment
- Low Pe0
- Outcome
- protein reservese0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Low P reduced utilization of starch and protein reserves in taproots.”
t0“Alfalfa”
Claim · model-written summary
High-affinity phosphorus transporter transcripts were undetectable in assayed roots and shoots regardless of treatment.
- Taxon
- AlfalfaMedicago sativat0
- Gene
- high-affinity P transportere0
- Outcome
- Transcripts for a high-affinity P transportere0
- Direction
- not detectede0
- Qualifier
- irrespective of defoliation or P treatmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Transcripts for a high-affinity P transporter were not detected in any root or shoot tissue assayed, irrespective of defoliation or P treatment.”
t0“Alfalfa”
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See all 13 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.