1-methylcyclopropene (1-MCP) increases CO2 injury in apples

The objective of this research was to determine the nature and extent of CO2 injury in apples treated with 1-methylcyclopropene (1-MCP) and stored in controlled atmosphere (CA). 'McIntosh' apples were treated immediately after harvest with 0, 60, 300, or 600 nL(.)L(-1) of 1-MCP for 18 to 24 hours at similar to20degreesC, and then placed in CA (3% O-2 + 2.5% CO2 for the first 30 days followed by 3% O-2 + 4.5% CO2 thereafter) for 70 and 140 days at 3degreesC. 'Empire' apples with or without ReTain(TM) application (200 muL(.)L(-1), 4 weeks prior to harvest) were treated similarly with 1-MCP immediately after harvest and placed in CA (2.5% O-2 + 2.0% CO2) for 120 and 240 days at 2degreesC. CO2 injury was promoted in 'McIntosh' by 1-MCP treatment, with up to 39% of the treated apples having external symptoms compared to zero incidence in the non-treated fruit. 'Empire' apples treated with 1-MCP also exhibited greater CO2 injury than those not treated, and the application of ReTain(TM) further promoted CO2 injury.