Ethephon

Ethephon is a plant growth regulator and ethylene-releasing compound used in agriculture. It is known chemically as 2-chloroethyl phosphonic acid and is sold under various trade names, including Ethrel. When applied to plant tissue, ethephon penetrates cells and is enzymatically hydrolyzed to release ethylene, a natural plant hormone that influences ripening, flowering, leaf drop, and other developmental processes.

The mechanism of action centers on ethylene release. Once inside plant tissues, ethephon undergoes hydrolysis to produce ethylene, phosphoric acid, and 2-chloroethanol. The ethylene then triggers physiological responses such as programmed ripening in climacteric fruits, defoliation in cotton to facilitate harvest, and induction of flowering or senescence in some ornamental species. The timing and concentration of application determine the specific developmental responses observed.

Applications of ethephon are diverse. It is widely used to accelerate fruit ripening in crops like bananas, citrus, apples, tomatoes, and mangoes; to promote leaf drop and boll opening in cotton; and to influence flowering and abscission in certain ornamentals. Application is typically achieved by spraying or dipping at label-specific doses and timing, with adherence to preharvest intervals and safety guidelines.

Safety and regulatory status vary by country. Ethephon is generally considered of moderate acute toxicity, can cause skin or eye irritation, and degrades rapidly through hydrolysis in the environment. Residue levels are managed by crop-specific labeling, and its use may be restricted or prohibited in organic farming. Always follow local regulations and product labels.