Greetings All

I'm doing a little experiment with growing plants and the effects vary
magnetic fields on them.
I would like to grow plants in a test tube and measure there growth.
What types of seeds would be the best to use that's fast growing and
will grow in water. I know I could use bean sprouts but I have to
drain the water after awhile. Is their a seed / plant that I can
leave in water and watch it grow in water alone? And if so where can
I find these seeds.

aloha
Rick