The study was conducted to determine if ethylene or ethephon, an ethylene-releasing compound, can be used to induce abscission of phylloclades of four cultivars of Easter cactus [Rhipsalidopsis gaertneri (Regel) Moran] to increase efficiency in vegetative propagation. Abscission occurred within 24 hours after commencement of the ethylene treatments. Phytotoxicity, as exhibited by water soaking, transparency, and darkening of the phylloclades, as well as percent abscission, increased with increasing concentrations of ethephon (0 to 10,000 μl·liter–1). Ethylene released from ethephon, not the acidity of the solution, was determined to be the cause of the phytotoxicity. In three out of the four cultivars, vegetative and root growth from propagated phylloclades was significantly restricted by treatments with ethephon. In comparison, vegetative growth from phylloclades treated with ethylene at 20 μl·liter–1 was the same as from those treated with air. Root growth of the ethylene-treated phylloclades was not studied. The acidity of the ethephon solutions likely affected the growing regions, resulting in a reduction in growth. The study shows that treatment with ethylene gas or the use of pH-adjusted ethephon solutions may be an alternative to the labor-intensive procedures associated with vegetative propagation of Easter cactus. Chemical name used: 2-chloroethylphosphonic acid (ethephon).
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