Abstract
The objective of this study was to identify a compound(s) that may be responsible, at least in part, for alfalfa autotoxicity. We found that medicarpin (3‐hydroxy‐9‐methoxypterocarpan) is a compound produced by alfalfa ( Medicago sativa L.) that contributes to this. clay loam soil from a declining alfalfa stand with two plants per 930 cm 2 and its 95% ethanol extract inhibited alfalfa emergence and seedlingrowth whereas extracted soil did not. The soil extracts contained at least 10 mg kg −1 medicarpin. Medicarpin, 4‐methoxymedicarpin, sativan, and 5′‐methoxysativan were isolated from alfalfa foliage with 95% ethanol, purified, identified by gas chromatography‐ mass spectroscopy, and then exogenously applied to alfalfa and velvetleaf ( Abutilon theophrasti L.) seeds using an agar bioassay. Medicarpin at 1 ✕ 10 −7 tool/seed reduced both alfalfa and velvetleaf seedling length by 39% after 72 h. Sativan and both methoxy derivatives had no affect on germination or seedingrowth. In a timecourse study, 2 ✕ 10 −7 mole/seed medicarpin delayed germination 12 h and seedling growth 44 h, during this time the alfalfa seedlings metabolized 85% of the medicarpin. Seedling growth then resumed at the control rate. Medicarpin is produced by mature alfalfa, is present in soil from a declining alfalfa stand, and is absorbed by alfalfa seedlings where it is metabolized and exerts a transient phytotoxic effect. Medicarpin may permit established alfalfa plants to control the ecology in their immediate proximity by inhibiting seedling establishment of nearby plants, thereby gaining a competitive advantage.
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Claims 11
Claim · model-written summary
Soil from a declining alfalfa stand inhibited alfalfa emergence and seedling growth.
- Taxon
- alfalfa
Medicago sativae0 - Treatment
- clay loam soil from a declining alfalfa stande0
- Outcome
- alfalfa emergence and seedlingrowthe0
- Direction
- inhibitede0
- Comparator
- extracted soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“clay loam soil from a declining alfalfa stand with two plants per 930 cm 2 and its 95% ethanol extract inhibited alfalfa emergence and seedlingrowth whereas extracted soil did not.”
Claim · model-written summary
The soil ethanol extract inhibited alfalfa emergence and growth.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- 95% ethanol extracte0
- Outcome
- alfalfa emergence and seedlingrowthe0
- Direction
- inhibitede0
- Comparator
- extracted soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“its 95% ethanol extract inhibited alfalfa emergence and seedlingrowth whereas extracted soil did not.”
Claim · model-written summary
Soil extracts contained at least 10 mg kg −1 medicarpin.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- medicarpine0
- Value
- at least 10 mg kg −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The soil extracts contained at least 10 mg kg −1 medicarpin.”
t0“Alfalfa”
Claim · model-written summary
Medicarpin reduced alfalfa seedling length by 39% after 72 h.
- Taxon
- alfalfaMedicago sativae0
- Treatment
- Medicarpin at 1 ✕ 10 −7 tool/seede0
- Outcome
- alfalfa and velvetleaf seedling lengthe0
- Direction
- reducede0
- Value
- 39%e0
- Qualifier
- after 72 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicarpin at 1 ✕ 10 −7 tool/seed reduced both alfalfa and velvetleaf seedling length by 39% after 72 h.”
Claim · model-written summary
Medicarpin reduced velvetleaf seedling length by 39% after 72 h.
- Taxon
- velvetleaf
Abutilon theophrastie0 - Treatment
- Medicarpin at 1 ✕ 10 −7 tool/seede0
- Outcome
- velvetleaf seedling lengthe0
- Direction
- reducede0
- Value
- 39%e0
- Qualifier
- after 72 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Medicarpin at 1 ✕ 10 −7 tool/seed reduced both alfalfa and velvetleaf seedling length by 39% after 72 h.”
Claim · model-written summary
Sativan did not affect germination or seedling growth.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Sativane0
- Outcome
- germination or seedingrowthe0
- Direction
- no affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sativan and both methoxy derivatives had no affect on germination or seedingrowth.”
t0“Alfalfa”
Claim · model-written summary
The methoxy derivatives did not affect germination or seedling growth.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- both methoxy derivativese0
- Outcome
- germination or seedingrowthe0
- Direction
- no affecte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sativan and both methoxy derivatives had no affect on germination or seedingrowth.”
t0“Alfalfa”
Claim · model-written summary
Medicarpin delayed alfalfa germination by 12 h.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- 2 ✕ 10 −7 mole/seed medicarpine0
- Outcome
- germinatione0
- Direction
- delayede0
- Value
- 12 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“2 ✕ 10 −7 mole/seed medicarpin delayed germination 12 h and seedling growth 44 h”
t0“Alfalfa”
Claim · model-written summary
Medicarpin delayed alfalfa seedling growth by 44 h.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- 2 ✕ 10 −7 mole/seed medicarpine0
- Outcome
- seedling growthe0
- Direction
- delayede0
- Value
- 44 he0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“2 ✕ 10 −7 mole/seed medicarpin delayed germination 12 h and seedling growth 44 h”
t0“Alfalfa”
Claim · model-written summary
Alfalfa seedlings metabolized 85% of medicarpin during the delay.
- Taxon
- alfalfaMedicago sativae0
- Outcome
- metabolizede0
- Value
- 85%e0
- Qualifier
- during this timee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“during this time the alfalfa seedlings metabolized 85% of the medicarpin.”
Claim · model-written summary
Alfalfa seedling growth resumed at the control rate.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Seedling growthe0
- Direction
- resumede0
- Comparator
- control ratee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Seedling growth then resumed at the control rate.”
t0“Alfalfa”
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botanical · growth · Medicago sativa (alfalfa)Results differ
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