There are two interesting things here from a legal perspective. 1. Licensing works on the commercial seeds because they are patented, and thus the company that

There are two interesting things here from a legal perspective. 1. Licensing works on the commercial seeds because they are patented, and thus the company that makes those seeds can dictate license terms on the farmers. As far as I can tell, these open seeds are not patented and thus their creators can't really impose license terms on the buyers unless they sign a contract before sale. That would be treated solely under contract law, not patent/copyright law. 2. Apparently these seeds use some sort of shrink-wrap license agreement as quoted below, which attempts to form the contract agreement mentioned in #1. "The license is printed on every OSS seed package in Europe. Whoever opens an OSS package agrees to never patent these seeds or future breeding of them." Considering the general dislike for/legal questionably behind shrink-wrap agreements, this sounds like a very poor way to enforce the OSS license. Also it is uncertain how valid this agreement is unless the seeds are patented (in that case the buyer's OSS rights can be granted via patent license terms).