You might have the right to protect your specific process of breeding that variety of onion. But if you then sell the seeds to grow that onion you've sold the a

You might have the right to protect your specific process of breeding that variety of onion. But if you then sell the seeds to grow that onion you've sold the ability to grow that onion to another person. It's intrinsic to what an onion is. You could argue the only legal way to protect it would be to only sell the onion products and never the seeds or bulbs yourself.