Possible Commercial Protocols for Recovering Ripening Capacity of 1-MCP-treated European Pears

A continuing challenge for commercializing 1-methylcyclopropene (1-MCP) to extend the storage life and control superficial scald (SS) of European pears (Pyrus communis L.) is how to initiate ripening capacity (RC) in 1-MCP treated fruit following cold storage. The objective of this study was to develop commercially feasible protocols for controlling postharvest disorders of pears through postharvest application of 1-MCP at commercially manageable dosage (i.e., 150 ppb) while allowing ripening to outstanding eating quality. The following strategies were investigated: 1) storing 1-MCP treated ‘Anjou’ pears at elevated storage temperatures; 2) simultaneous application of 1-MCP and ethylene; 3) post-storage ethylene conditioning (PSEC); 4) delaying 1-MCP application; and 5) late harvest. As expected, 1-MCP inhibited ethylene production in ‘Anjou’ pears during cold storage and the 1-MCP treated fruit developed neither SS nor RC in 7 d at 20 °C following eight months of storage at the traditional storage temperature of –1.1 °C. A storage temperature of 1.1 °C facilitated initiation of RC in 1-MCP treated fruit with relatively low SS following six to eight months of storage through recovering the expression of ethylene synthesis (PcACS1, PcACO1) and signal (PcETR1, PcETR2) genes. ‘Anjou’ pears treated with 1-MCP + ethylene simultaneously at 300:300–600ppb recovered RC with low SS following 6-8 months of storage at -1.1 °C. PSEC could ripen the 1-MCP treated ‘Anjou’ pears produced at high elevations (i.e., 610 m) and its bud mutation ‘Columbia Red Anjou’ pears following six to eight months of storage at –1.1 °C. PcACO1 plays an important role in initiating RC in 1-MCP treated red ‘Anjou’ pear upon PSEC treatment. Delaying 1-MCP application after harvest and late harvest may not be useful protocols for ripening 1-MCP treated ‘Anjou’ pears due to inconsistent efficacies among production lots and years.