ethylene gas is one of the 5 main known plant hormones. I believe it is used in ripening of flowers and fruits. Not sure what kind of role it plays in determination of sex during early stages.

As for estrogen.. Thats a human hormone. Not a plant hormone. Any increase in female to male ratio after treatment with estrogen is most likely a coincidence.

The ethylene gas theory does have some merrit how ever as ethylene is a known plant hormone.

For your information too.. I do believe when it was discovered it was thought that heat was rippening fruits. Farmers used to harvest fruit when they were green and place them in sheds with (I think kerosine) heaters. The fruits used to ripen nicely, and uniformly. Later there was a change in technology. Kerosine was not used and a different heating source was used. However this failed. It turns out that kerosine being burnt produces ethylene gas. I'v often wondered if you could decrease the flower time of a marijuana crop by introducing ethylene gas into your grow area. You could also probly get the lower buds to ripen up at the same time as the top buds. Have not to this date tried this experiment but might do so in the future.
AussieBushMan Reviewed by AussieBushMan on . Treatment of seeds w ethylene gas = more females?? Hey Guys Check this out. I saw this info while surfing the web a while ago. I copied and pasted to my MS Word. Sorry i dont have the source for you guys..what do you think of these methods???? Treatment of seeds with ethylene gas will increase the resulting number of female plants by about 50%. Ethylene is produced by certain plants (i.e., bananas, cucumbers and melons), and these can be used to treat hempseed in a simple manner. About two weeks before you plan to sprout the seeds, Rating: 5