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  • So, the apocalypse has happened.

  • The zombies have come and gone,

  • and all plant life on Earth has died somehow.

  • All you have are some basic supplies

  • and some seeds of a few types of essential plants.

  • So, what should you do

  • to make absolutely sure they grow,

  • seeing how rebuilding human civilization

  • absolutely depends on it?

  • Well, you'd probably think

  • the last thing you should do

  • with these crucially important seeds

  • is something like poking holes in them,

  • or grinding them with sandpaper,

  • or throwing them in acid

  • or hot water.

  • But, in fact, all of these are methods

  • that are commonly used

  • to help seeds start growing.

  • A typical seed consists of a plant embryo

  • encased in a hard seed coat.

  • To start growing,

  • it needs to emerge or sprout

  • from inside this shell.

  • This process is called germination.

  • But just as it would be hard

  • for you to get out of a jail cell

  • with no windows and no doors,

  • the embryo might need a little help

  • escaping from its seed prison,

  • and any process that makes this easier

  • by wearing down the seed coat

  • is called scarification.

  • This lets moisture and nutrients

  • get through the seed coat,

  • making the embryo start growing

  • until it breaks through.

  • Now, you might be wondering

  • why it is that plants would need humans

  • to do all these weird things to their seeds

  • in order to grow,

  • and, in fact, they don't.

  • In natural environments,

  • seed coats are worn down by cold temperatures,

  • bacteria,

  • or even animal digestion.

  • Our scarification methods just mimick

  • and accelerate these natural processes

  • to increase the chances of successful germination.

  • One technique we can use is called nicking.

  • To do this, we make a small cut or scratch

  • into the seed coat.

  • Be careful not to cut too deep!

  • You don't want to damage the plant embryo inside.

  • Another way is to file down the seed coat

  • using sandpaper or a nail file.

  • Once again, you don't want to file too much,

  • just enough to wear down some of the seed coat.

  • After applying either of these methods,

  • you'll want to spray the seeds with bleach

  • to prevent mold.

  • Seeds can also be soaked in water

  • to soften the coat.

  • One way to do this

  • is to place the seeds in a nylon bag,

  • then place the bag into hot water.

  • Turn off the heat immediately

  • and allow the water to cool to room temperature

  • before removing the seeds.

  • It's important not to heat the seed for too long

  • as this will kill the embryo.

  • Again, you'll want to spray them

  • with bleach afterwards.

  • Finally, you can try immersing the seeds

  • in a sulfuric acid solution.

  • Make sure you're wearing protective goggles and gloves

  • any time you work with such a dangerous substance.

  • Place the seeds into a wire mesh pouch

  • and immerse the pouch in the solution for ten minutes.

  • Then take out the pouch

  • and rinse it with clean water.

  • Take out the seeds and, as before,

  • spray them with bleach so they don't get moldy.

  • If you try all of these methods,

  • you will see that some of them

  • are more effective than others,

  • and some work best for different types of plants

  • that have harder or thicker coats.

  • So, knowing what seed scarification techniques work best

  • will be useful if you ever need to survive a cataclysm,

  • start a farm,

  • or just want to plant in your own garden.

So, the apocalypse has happened.

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B2 TED-Ed seed embryo coat bleach sandpaper

【TED-Ed】Got seeds? Now add bleach, acid and sandpaper - Mary Koga

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    VoiceTube posted on 2013/10/13
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