Speaking of production of feminized seeds: Also Gibberelic Acid (GA3) has been used to mutate female flowers to induce male flowering and pollinate itself… This way is not so much effective, because plants also stretch to much…
There is some article about GA3 in FAQ also:
Also there is Silver Thiosulfate (STS) which has same results for feminization as Colloidal Silver. But it is hard to find.