# Ethylene

> A gaseous plant hormone that regulates ripening, senescence, stress responses and, in cannabis, female flower expression; blocking it makes females produce pollen.

- Canonical: https://genetixbay.com/knowledge/glossary/ethylene.html
- Also written: ethene, C2H4, ripening hormone, ethylene gas
- Glossary category: Plant biology · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Ethylene (C₂H₄) is a simple gas that acts as a plant hormone. It promotes [fruit](https://genetixbay.com/knowledge/glossary/achene.md) ripening, leaf and flower senescence, abscission, and responses to wounding, flooding and other stress. In cannabis it also promotes [female flower](https://genetixbay.com/knowledge/glossary/pistillate-flower.md) development; blocking ethylene signalling pushes female plants to form [male flowers](https://genetixbay.com/knowledge/glossary/staminate-flower.md).

## In practice

That last point is the basis of [feminised seed](https://genetixbay.com/knowledge/glossary/feminised-seed.md). Silver ions block ethylene receptors, so sprays of [silver thiosulfate](https://genetixbay.com/knowledge/glossary/sts.md) (STS) or silver nitrate on a female plant induce fertile male flowers (Ram & Sett 1982; Lubell & Brand 2018). Pollen from that [reversed female](https://genetixbay.com/knowledge/glossary/sex-reversal.md) carries no Y chromosome, so the seeds are female.

Ethylene also builds up around stressed or damaged tissue and in closed spaces. Ripening fruit stored with cut material, or [waterlogged](https://genetixbay.com/knowledge/glossary/overwatering.md) roots producing ethylene precursors, can speed yellowing and leaf drop.

Ethylene-releasing products are sometimes promoted for "ripening" cannabis faster. Evidence of a quality benefit in cannabis is thin. Treat as Contested and keep it off consumable crops unless the data improves.

## Don't confuse with

- **Ethanol**: an alcohol, not a hormone.
- **Gibberellin**: tends to push toward male expression.
- **Abscisic acid**: the main drought-stress hormone.

## Related terms

[Gibberellin](https://genetixbay.com/knowledge/glossary/gibberellin.md), [Senescence](https://genetixbay.com/knowledge/glossary/senescence.md), [Hermaphrodite](https://genetixbay.com/knowledge/glossary/hermaphrodite.md), [Abscisic acid](https://genetixbay.com/knowledge/glossary/abscisic-acid.md)

## Read more

- [Feminised seed and sex reversal: methods, with safety notes](https://genetixbay.com/knowledge/breeding/feminised-seed-sex-reversal.md)

## Sources

1. Ram HYM, Sett R. 1982. Induction of fertile male flowers in genetically female Cannabis sativa plants by silver nitrate and silver thiosulphate anionic complex. Theoretical and Applied Genetics 62:369-375. https://doi.org/10.1007/BF00275107
2. Lubell JD, Brand MH. 2018. Foliar sprays of silver thiosulfate produce male flowers on female hemp plants. HortTechnology 28(6):743-747. https://doi.org/10.21273/HORTTECH04188-18
3. Taiz L, Zeiger E, Møller IM, Murphy A. 2015. Plant Physiology and Development, 6th edition. Sinauer Associates.