To produce feminized seeds, seed makers typically use a process called “selfing,” which involves crossing a female plant with itself. This can be achieved by inducing the plant to produce male flowers, which will pollinate the female flowers and produce seeds that are genetically identical to the original female plant.

To induce male flowers on a female plant, breeders use STS to block the action of ethylene, a plant hormone that is responsible for promoting female flower development. By treating a female plant with STS during the early stages of flowering, breeders can cause it to produce male flowers instead. The resulting pollen can then be used to fertilize the female flowers of the same plant, resulting in feminized seeds.