It's a sick system, perpetuated by sick people
There’s plenty of universities, cooperatives, and passionate growers who have developed crops and seeds in the past and will surely continue to do so in the future.
The patent system is useful to address very specific market failures in very specialized industries where the above systems fail, not to turn the whole world into a rental unit.
The patent system doesn't prevent those entities from developing their own crops and releasing it for free.
When a company is granted a utility patent on a type of seed, it doesn’t just own the seed. It also owns its traits (color, texture, disease resistance, the way it was grown), future generations of that seed and all of the rights to research.
So, if a plant breeder like Morton develops his own variety of lettuce and the lettuce matches any of the traits of a patented variety – whether it be color, the curliness of the leaf or a trait that makes it conducive to a particular climate – the breeder is technically in violation of patent law and risks getting sued by the patent owner.
So according to the article, the patent system actually does place heavy restrictions on research in this area.
First off, a year or two before the patents on a variety expire, they simple patent some other feature of the variety. Problem solved (from their perspective).
Second, several years before the patent expires on a variety they'll have a "new, improved" variety (often bred from the first) that their sales-people push hard onto farmers so that by the time the patent expires the variety basically has very little/no commercial value - it's been superseded by the "improved" variety in commercial use.