Abstract
Freezing at an ultralow temperature and thawing was shown in 1930 to decrease hard-seededness of alfalfa but the method has never been applied commercially. Freezing equipment now exists that could be adapted for freezing batches of alfalfa seed. Thus this study was conducted to evaluate the effectiveness of freeze-thaw treatments to reduce hard-seededness of two alfalfa seed lots known to have hard seed. A study was also conducted to determine if freeze-thawing of seeds has any negative effects on subsequent plant growth. Freezing to -10°C was ineffective but freezing to -80°C was highly effective at decreasing hard-seededness. Freeze-thaw treatments effectively decreased hard seed content of seed lots of a purple flowered alfalfa (Medicago sativa L.) cultivar, Peace, and a yellow flowered alfalfa (Medicago falcata L.) cultivar, Anik. Hard seed content decreased exponentially with the number of freeze-thaw cycles. With a freeze thaw cycle consisting of 2 h exposure to -80°C and 2 or 18 h thaw at 20°C, it took 1.6 cycles to decrease Peace hard seed by 50% and 2.6 cycles to decrease Anik hard seed by 50%. The -80°C freeze-thaw treatments increased rate of germination based on total seed population, total germination, rate of seedling development, and number of seedlings established. Freeze-thawing does not affect nonhard seeds since the freeze-thaw treatment had no effect on the rate of seed germination when based only on the population of seeds germinating. Freeze-thaw treatment of seed had no effect on seedling vigor as measured by dry matter production. The freeze-thaw treatment is an effective method for decreasing alfalfa hard-seededness; thus, an economic analysis of its use for commercial application is required. Additional index words: Medicago, Germination, Seedcoat, Permeable, Temperature.
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Claims 12
Claim · model-written summary
Freezing alfalfa seed to -10°C was ineffective at decreasing hard-seededness.
- Taxon
- alfalfa
Medicago sativat0 - Treatment
- Freezing to -10°Ce1
- Outcome
- hard-seedednesse1
- Direction
- ineffectivee1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“Freezing to -10°C was ineffective but freezing to -80°C was highly effective at decreasing hard-seededness”
Claim · model-written summary
Freezing alfalfa seed to -80°C was highly effective at decreasing hard-seededness.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- freezing to -80°Ce1
- Outcome
- hard-seedednesse1
- Direction
- decreasinge1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“Freezing to -10°C was ineffective but freezing to -80°C was highly effective at decreasing hard-seededness”
Claim · model-written summary
Freeze-thaw treatments effectively decreased hard seed content of seed lots of the purple flowered alfalfa cultivar Peace (Medicago sativa).
- Taxon
- Medicago sativa L.Medicago sativae1
- Material
- Peacee1
- Treatment
- Freeze-thaw treatmentse1
- Outcome
- hard seed contente1
- Direction
- decreasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Freeze-thaw treatments effectively decreased hard seed content of seed lots of a purple flowered alfalfa (Medicago sativa L.) cultivar, Peace, and a yellow flowered alfalfa (Medicago falcata L.) cultivar, Anik”
Claim · model-written summary
Freeze-thaw treatments effectively decreased hard seed content of seed lots of the yellow flowered alfalfa cultivar Anik (Medicago falcata).
- Taxon
- Medicago falcata L.
Medicago sativa subsp. falcatae1 - Material
- Anike1
- Treatment
- Freeze-thaw treatmentse1
- Outcome
- hard seed contente1
- Direction
- decreasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Freeze-thaw treatments effectively decreased hard seed content of seed lots of a purple flowered alfalfa (Medicago sativa L.) cultivar, Peace, and a yellow flowered alfalfa (Medicago falcata L.) cultivar, Anik”
Claim · model-written summary
Alfalfa hard seed content decreased exponentially with the number of freeze-thaw cycles.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- number of freeze-thaw cyclese1
- Outcome
- Hard seed contente1
- Direction
- decreasede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“Hard seed content decreased exponentially with the number of freeze-thaw cycles”
Claim · model-written summary
With a cycle of 2 h at -80°C and 2 or 18 h thaw at 20°C, 1.6 cycles were needed to decrease Peace hard seed by 50%.
- Taxon
- alfalfaMedicago sativat0
- Material
- Peacee1
- Treatment
- freeze thaw cycle consisting of 2 h exposure to -80°C and 2 or 18 h thaw at 20°Ce1
- Outcome
- hard seede1
- Direction
- decreasee1
- Value
- 1.6 cyclese1
- Qualifier
- by 50%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“With a freeze thaw cycle consisting of 2 h exposure to -80°C and 2 or 18 h thaw at 20°C, it took 1.6 cycles to decrease Peace hard seed by 50% and 2.6 cycles to decrease Anik hard seed by 50%”
Claim · model-written summary
With a cycle of 2 h at -80°C and 2 or 18 h thaw at 20°C, 2.6 cycles were needed to decrease Anik hard seed by 50%.
- Taxon
- alfalfaMedicago sativat0
- Material
- Anike1
- Treatment
- freeze thaw cycle consisting of 2 h exposure to -80°C and 2 or 18 h thaw at 20°Ce1
- Outcome
- hard seede1
- Direction
- decreasee1
- Value
- 2.6 cyclese1
- Qualifier
- by 50%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“With a freeze thaw cycle consisting of 2 h exposure to -80°C and 2 or 18 h thaw at 20°C, it took 1.6 cycles to decrease Peace hard seed by 50% and 2.6 cycles to decrease Anik hard seed by 50%”
Claim · model-written summary
The -80°C freeze-thaw treatments increased the rate of germination (total seed population basis) and total germination of alfalfa seed.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- -80°C freeze-thaw treatmentse1
- Outcome
- rate of germination based on total seed population, total germinatione1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“The -80°C freeze-thaw treatments increased rate of germination based on total seed population, total germination, rate of seedling development, and number of seedlings established”
Claim · model-written summary
The -80°C freeze-thaw treatments increased the rate of seedling development and the number of seedlings established in alfalfa.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- -80°C freeze-thaw treatmentse1
- Outcome
- rate of seedling development, and number of seedlings establishede1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“The -80°C freeze-thaw treatments increased rate of germination based on total seed population, total germination, rate of seedling development, and number of seedlings established”
Claim · model-written summary
Freeze-thaw treatment had no effect on the rate of germination of alfalfa seeds when based only on the population of seeds germinating (non-hard seeds).
- Taxon
- alfalfaMedicago sativat0
- Treatment
- freeze-thaw treatmente1
- Outcome
- rate of seed germinatione1
- Direction
- no effecte1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“the freeze-thaw treatment had no effect on the rate of seed germination when based only on the population of seeds germinating”
Claim · model-written summary
Freeze-thaw treatment of alfalfa seed had no effect on seedling vigor measured as dry matter production.
- Taxon
- alfalfaMedicago sativat0
- Treatment
- Freeze-thaw treatmente1
- Outcome
- seedling vigore1
- Direction
- no effecte1
- Qualifier
- as measured by dry matter productione1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“Freeze-thaw treatment of seed had no effect on seedling vigor as measured by dry matter production”
Claim · model-written summary
The authors state that an economic analysis of freeze-thaw use for commercial application of alfalfa seed is required.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- economic analysise1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa”
e1“an economic analysis of its use for commercial application is required”
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