Subject: How does radiation affect seed growth?

I'm working on a science fair project on the effects of radiation on 
seed growth. In my experiment, I radiated radish and bean seeds in
my microwave for 10 seconds. I planted these seeds as well as a set 
of seeds that were not radiated. Here are my results:  the radiated 
seeds germinated faster, but in the long run, they ended not growing 
as tall as the regular ones. The regular seeds were much more
 healthier. Why did the radiation do this?

Is there any scientific explanation for my results that I can use in my report? 

Re: How does radiation affect seed growth?