Responses of 1-methylcyclopropene (1-MCP)-treated banana fruit to pre- and post-treatment ethylene exposure

1-Methylcyclopropene (1-MCP), an ethylene receptor blocker, is mostly applied in gas form to inhibit ethylene action. An alternative immersion application method was used to investigate how pre- or post-1-MCP exposure to ethylene influences banana fruit response to 1-MCP. Mature-green (MG) banana fruit were immersed in 0, 10, 25 or 50 mu g L-1 1-MCP (a.i.) solution at 20 degrees C to determine the most effective concentration. The bananas were exposed to 0 or 100 mu L L-1 ethylene for 24 h prior to (+/ -preETH) or continuously following (+/ postETH) 1-MCP treatment to determine its effect on 1-MCP inhibition of ripening. Ripening of 1-MCP-treated fruit was delayed by up to 12 d at 20 degrees C, but that effect was reduced by circa 60% with ethylene pre-treatment. Recovery from 1-MCP in terms of ripening initiation occurred 4 to 6 d earlier in the presence of continuous post-treatment ethylene compared with air and the time to the fully ripe stage for 1-MCP plus ethylene fruit was 2 d shorter than for fruit without ethylene. Uneven recovery of fruit from 1-MCP was observed at stage 5, when the fruit had softer central pericarp and firmer external pericarp that adhered to the peel, but `normal', uniformly soft pulp developed at stage 7 and later. Since post-treatment ethylene exposure accelerated the recovery of ripening after 1-MCP application in terms of earlier onset and accelerated rate of ripening, it could be suggested that ethylene may promote generation of new ethylene receptors.