If the importance of heirloom plants to your emergency preparedness is news to you, then you do not know the worst of it yet.
Heirloom plants come from seeds that are saved from the seeds that are planted that year. This is in order to have seeds to plant next year. Seed companies save people from needing to go to that trouble to save their own seeds for next year.
When seed companies sell hybrid seeds, the plants that grow from those seeds will often not produce very good seeds. Some varieties don't even have seeds. That means the people who buy those seeds cannot save their own seeds even if they want to. They always have to buy their seeds from the seed companies.
That situation is an even bigger advantage for seed companies that sell GMO seeds. The GMO seeds are produced in a laboratory and usually patented. Even if someone managed to find a good GMO seed, it would be illegal for them to grow that seed without permission from the patent holder.
Fewer and fewer seed companies are getting bigger and bigger and they are connected or owned by the labs that make the GMO seeds. This means that more and more of the world's agriculture is becoming dependent on very large agribusinesses that are becoming monopolies over seeds. These are seeds that the world depends on for food for survival.
This is not good for people who need to eat and do not own large agribusinesses and large seed and GMO labs.
It is a good idea to have some heirloom seeds in your preparedness supplies. It is an even better idea for you to know how to grow those heirloom seeds. It takes a while to learn to grow a garden, especially if you need to grow enough to survive on.
If you raise heirloom seeds, and save some seeds for next year, and pass some of your extra seeds along to others who will do the same thing, you are helping to fight monopolies on seeds that people of the world need to survive.
Even if you do not have a garden or a place for a garden, you can probably keep a pot or two on a windowsill and grow an heirloom seed or two and save the seeds from it. You will be helping yourself and everyone else as well. You should get a medal, because you would be a hero.