Got seeds? Just add bleach, acid and sandpaper - Mary Koga

852,802 views ・ 2013-07-16

TED-Ed


Please double-click on the English subtitles below to play the video.

00:13
So, the apocalypse has happened.
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The zombies have come and gone,
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and all plant life on Earth has died somehow.
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All you have are some basic supplies
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and some seeds of a few types of essential plants.
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So, what should you do
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to make absolutely sure they grow,
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seeing how rebuilding human civilization
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absolutely depends on it?
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Well, you'd probably think
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the last thing you should do
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with these crucially important seeds
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is something like poking holes in them,
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or grinding them with sandpaper,
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or throwing them in acid
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or hot water.
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But, in fact, all of these are methods
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that are commonly used
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to help seeds start growing.
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A typical seed consists of a plant embryo
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encased in a hard seed coat.
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To start growing,
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it needs to emerge or sprout
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from inside this shell.
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This process is called germination.
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01:01
But just as it would be hard
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for you to get out of a jail cell
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with no windows and no doors,
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the embryo might need a little help
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escaping from its seed prison,
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and any process that makes this easier
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by wearing down the seed coat
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is called scarification.
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This lets moisture and nutrients
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get through the seed coat,
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making the embryo start growing
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until it breaks through.
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Now, you might be wondering
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why it is that plants would need humans
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to do all these weird things to their seeds
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in order to grow,
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and, in fact, they don't.
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In natural environments,
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seed coats are worn down by cold temperatures,
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bacteria,
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or even animal digestion.
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Our scarification methods just mimick
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and accelerate these natural processes
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to increase the chances of successful germination.
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One technique we can use is called nicking.
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To do this, we make a small cut or scratch
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into the seed coat.
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Be careful not to cut too deep!
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You don't want to damage the plant embryo inside.
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Another way is to file down the seed coat
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using sandpaper or a nail file.
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Once again, you don't want to file too much,
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just enough to wear down some of the seed coat.
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After applying either of these methods,
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you'll want to spray the seeds with bleach
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to prevent mold.
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Seeds can also be soaked in water
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to soften the coat.
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One way to do this
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is to place the seeds in a nylon bag,
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then place the bag into hot water.
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Turn off the heat immediately
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and allow the water to cool to room temperature
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before removing the seeds.
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It's important not to heat the seed for too long
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as this will kill the embryo.
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Again, you'll want to spray them
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with bleach afterwards.
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Finally, you can try immersing the seeds
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in a sulfuric acid solution.
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Make sure you're wearing protective goggles and gloves
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any time you work with such a dangerous substance.
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Place the seeds into a wire mesh pouch
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and immerse the pouch in the solution for ten minutes.
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Then take out the pouch
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and rinse it with clean water.
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Take out the seeds and, as before,
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spray them with bleach so they don't get moldy.
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If you try all of these methods,
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you will see that some of them
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are more effective than others,
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and some work best for different types of plants
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that have harder or thicker coats.
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So, knowing what seed scarification techniques work best
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will be useful if you ever need to survive a cataclysm,
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start a farm,
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or just want to plant in your own garden.
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