Preventing Ethylene Responses in Tropical Crops by Using Novel Non-Volatile Cyclopropene Formulation

In many studies cyclopropene compounds have been shown to be effective blockers of ethylene responses in plants. Because of the volatile character of most cyclopropenes, treatment of plant material is limited to enclosed systems. For outdoor applications, non-volatile formulations are desired. In the present study we report the use of newly synthesised non-volatile cyclopropene with a methyl group in the 1-position, on which a substituted amine was attached. When diluted with a weak acid such as acetic, formic, carbonic or phosphoric, a non-volatile salt is formed which can be applied as a spray. N,N-dipropyl(1 cyclopropenylmethyl) amine (DPCA) was applied to plant material as a gas, dip or spray. Two tropical plant species: banana Musa paradisiaca L. and orchid Phalaenopsis ‘Lila’ were treated with a range of concentrations of DPCA. After chemical application the plant material was treated with ethylene or kept in ethylene-free air. Postproduction quality of orchid flowers and chlorophyll degradation in banana peel were used as indicators of the protective effect of DPCA against ethylene action. The optimum concentration of DPCA varied between tested plant material, but the best concentrations gave protection against ethylene for 33 days in banana Musa paradisiaca and around 15 days in Phalaenopsis orchid flowers.