Abstract
Abstract Alfalfa (Medicago sativa L.) root reserves are thought to provide nutrients to regrowing shoots, enhance stress tolerance, and improve plant persistence. Factors affecting carbohydrate and protein accumulation and metabolism in roots are important in alfalfa production. Our objectives were to determine 1) the influence of phosphorus (P) nutrition on alfalfa shoot growth and root carbohydrate and protein metabolism after defoliation and 2) how quickly growth and root carbohydrate and protein metabolism of P‐deficient alfalfa plants responds to supplemental P. In Experiment 1, nodulated alfalfa was grown in quartz sand with minus‐nitrogen (N) Hoagland's solution containing 0,1,2, or 6 mM P. Root P concentrations increased with increasing solution P levels. Phytate P in roots of plants grown with 6 mM P was greater than that of plants grown in 0, 1, or 2 mM P. Shoot mass and shoots per plant were reduced by 67 and 43%, respectively, in plants grown with 0 mM P as compared to plants grown with 6 mM P. Root starch and protein concentrations did not decline after defoliation in plants provided 0 mM P. Defoliation increased endoamylase activity in roots of plants that received P. Root total amylase activity declined as P supply increased, and was not associated with root starch degradation. In Experiment 2, P‐deficient alfalfa plants were provided with minus‐N Hoagland's solution containing 6 mM P either at defoliation (Day 0), or at Day 14, and these plants were compared to others provided 0 or 6 mM P throughout the study. Root P concentrations increased within 7 days of P application. Shoot regrowth of P‐deficient plants recovered to equal that of plants provided 6 mM P within 7 to 21 days after P application. Application of P at defoliation enhanced root starch use, whereas P application on Day 14 had no effect on root starch depletion. Normal root starch utilization occurred in plants provided 6 mM P when plants were defoliated a second time 35 days after the initial harvest. Normal root protein utilization was not restored by P application during regrowth. Roots of P‐deficient alfalfa contained high concentrations of organic reserves, but use of these reserves after defoliation was impaired.
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Claims 16
Claim · model-written summary
Root P concentration increased with solution P.
- Taxon
- alfalfa
Medicago sativat0 - Treatment
- solution P levelse0
- Outcome
- Root P concentrationse0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root P concentrations increased with increasing solution P levels.”
t0“alfalfa”
Claim · model-written summary
Root phytate P was greater at 6 mM P than at 0, 1, or 2 mM P.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- 6 mM Pe0
- Outcome
- Phytate P in rootse0
- Direction
- greatere0
- Comparator
- 0, 1, or 2 mM Pe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phytate P in roots of plants grown with 6 mM P was greater than that of plants grown in 0, 1, or 2 mM P.”
t0“alfalfa”
Claim · model-written summary
At 0 mM P, shoot mass was 67% lower than at 6 mM P.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- 0 mM Pe0
- Outcome
- Shoot masse0
- Direction
- reducede0
- Value
- 67e0
- Comparator
- 6 mM Pe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot mass and shoots per plant were reduced by 67 and 43%, respectively, in plants grown with 0 mM P as compared to plants grown with 6 mM P.”
t0“alfalfa”
Claim · model-written summary
At 0 mM P, shoots per plant were 43% lower than at 6 mM P.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- 0 mM Pe0
- Outcome
- shoots per plante0
- Direction
- reducede0
- Value
- 43%e0
- Comparator
- 6 mM Pe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot mass and shoots per plant were reduced by 67 and 43%, respectively, in plants grown with 0 mM P as compared to plants grown with 6 mM P.”
t0“alfalfa”
Claim · model-written summary
Root starch and protein concentrations did not decline after defoliation at 0 mM P.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- defoliatione0
- Outcome
- Root starch and protein concentrationse0
- Direction
- did not declinee0
- Qualifier
- 0 mM Pe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root starch and protein concentrations did not decline after defoliation in plants provided 0 mM P.”
t0“alfalfa”
Claim · model-written summary
Defoliation increased root endoamylase activity in plants receiving P.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Defoliatione0
- Outcome
- endoamylase activity in rootse0
- Direction
- increasede0
- Qualifier
- received Pe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Defoliation increased endoamylase activity in roots of plants that received P.”
t0“alfalfa”
Claim · model-written summary
Root total amylase activity declined as P supply increased.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- P supplye0
- Outcome
- Root total amylase activitye0
- Direction
- declinede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root total amylase activity declined as P supply increased, and was not associated with root starch degradation.”
t0“alfalfa”
Claim · model-written summary
Root total amylase activity was not associated with root starch degradation.
- Taxon
- alfalfaMedicago sativat0
- Organ / stage
- roote0
- Outcome
- root starch degradatione0
- Qualifier
- not associated withe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root total amylase activity declined as P supply increased, and was not associated with root starch degradation.”
t0“alfalfa”
Claim · model-written summary
Root P concentration rose within seven days of P application.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- P applicatione0
- Outcome
- Root P concentrationse0
- Direction
- increasede0
- Value
- 7 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Root P concentrations increased within 7 days of P application.”
t0“alfalfa”
Claim · model-written summary
P application restored shoot regrowth to the level of continuously P supplied plants within 7 to 21 days.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- P applicatione0
- Outcome
- Shoot regrowthe0
- Direction
- recovered to equale0
- Value
- 7 to 21 dayse0
- Comparator
- plants provided 6 mM Pe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot regrowth of P‐deficient plants recovered to equal that of plants provided 6 mM P within 7 to 21 days after P application.”
t0“alfalfa”
Claim · model-written summary
P applied at defoliation enhanced root starch use.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Application of P at defoliatione0
- Outcome
- root starch usee0
- Direction
- enhancede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of P at defoliation enhanced root starch use”
t0“alfalfa”
Claim · model-written summary
P applied on day 14 had no effect on root starch depletion.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- P application on Day 14e0
- Outcome
- root starch depletione0
- Direction
- no effecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“P application on Day 14 had no effect on root starch depletion.”
t0“alfalfa”
Claim · model-written summary
Plants supplied 6 mM P used root starch normally after a second defoliation.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- 6 mM Pe0
- Outcome
- Normal root starch utilizatione0
- Qualifier
- defoliated a second time 35 days after the initial harveste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Normal root starch utilization occurred in plants provided 6 mM P when plants were defoliated a second time 35 days after the initial harvest.”
t0“alfalfa”
Claim · model-written summary
P application during regrowth did not restore normal root protein utilization.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- P application during regrowthe0
- Outcome
- Normal root protein utilizatione0
- Direction
- not restorede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Normal root protein utilization was not restored by P application during regrowth.”
t0“alfalfa”
Claim · model-written summary
P deficient roots retained high organic reserve concentrations but impaired use after defoliation.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- high concentrations of organic reservese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Roots of P‐deficient alfalfa contained high concentrations of organic reserves, but use of these reserves after defoliation was impaired.”
Claim · model-written summary
P deficient roots had impaired reserve use after defoliation.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- use of these reserves after defoliation was impairede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Roots of P‐deficient alfalfa contained high concentrations of organic reserves, but use of these reserves after defoliation was impaired.”
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