What I don’t understand is, _how_ it doesn’t depend on a patent right. How do you license something that doesn’t depend on a licensable right?

If it isn’t a patent right, exactly _what_ is he purchasing a license to? If it’s purely an agreement of exclusivity to Giumarra, it can’t be called a “sub license” and the consequence is just a breach of contract (which is what it sounds like). But in that case I’m sure there are mutual termination agreements in the exclusivity contract.

Also, if it’s _not_ a patent, what exactly does the company bring to the table? For what consideration does the farmer give them an exclusive access to his trees?

it could be seeds, rootstalk, cash, loans a future purchase guarantee. There is basically an endless list of reasons the contract could have been initially attractive for the farmer.

As you say, it mostly comes down to what the parties agreed to about exiting the contract.