Griffitts:Seed scarification and germination

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Alfalfa

Note: Alfalfa seeds don't need to be scarified

• Calculate the number of plants you need
• Weigh out ten times more than the number you need
  • Use GT13R Plus
  • 1.7 g is approximately 1000 seeds
• Place in a smooth sterile flask
• Add 70% ethanol to substantially cover the seeds
  • 70% ethanol is next to the scales
• Place on a shaker at room temperature at 150 rpm for 20 minutes
• Decant the ethanol and wash the seeds once with sterile dH₂0
• Add Clorox bleach to substantially cover the seeds
• Place on a shaker at room temperature at 150 rpm for 20 minutes
• Decant the bleach and wash the seeds 4 to 5 times with sterile dH₂0
• Add sterile dH₂0 to substantially cover the seeds
• Place on a shaker at room temperature at 150 rpm for at least 4 hours (preferably 8)
  • It's a good idea to wash the seeds with sterile dH₂0 once during this time
• Decant the sterile dH₂0 and add fresh sterile dH₂0
• Dump into 100×25 mm Petri dishes
  • Seeds should be in a monolayer with a small amount of space between them
• Pull off excess water with a pipet
  • Tip the plate and give it a few seconds to be sure to get all the excess water
• Wrap plate(s) in Parafilm
• Store upside-down in a drawer for 24 hours

Other Medics

• Place twice as many seeds as you wish to plant into a 50 mL Erlenmeyer flask that has been covered with foil and autoclaved.
• To each of the flasks add 5 ml of H₂SO₄ (sulfuric acid)
• Place on the shaker for the appropriate time (see table below)
• Remove the sulfuric acid
  • Discard it into the sulfuric acid waste container in the fume hood
• Immediately rinse the seeds once with dH₂0
• Add ~5 mL of bleach
• Place them back onto the shaker for two minutes
• Rinse five times with dH₂0
• Pour the seeds and some dH₂0 into small plates
• Parafilm and store in the fridge 24 hours to allow imbibement
  • Be sure not to have excessive amounts of water in the plate
• Remove the seeds from the fridge and remove the water
• Parafilm the mini-plates, invert and place at room temperature in the dark for one day
  

Note: some plants may take a little longer to germinate

Scarification times for different Medicago seedlings

species	time
arabica	15 minutes
constricta	10 minutes
disciformis	10 minutes
heyniana	20 minutes
italica	10 minutes
lesinsii	10 minutes
lupulina	20 minutes
polymorpha	20 minutes
praecox	10 minutes
rugosa	30 minutes
tenoreana	10 minutes
truncatula A7	10 minutes