The ethylene action inhibitor 1-methylcyclopropene (MCP) reduces the rate of ripening of many apple and pear cultivars. The longevity of MCP responses induced by a single application at harvest is dependent in part on MCP treatment concentration and post-application storage conditions. Experiments were conducted using several apple and pear cultivars to evaluate the efficacy of repeated application to prolong the duration of MCP responses. Fruit were treated with MCP at harvest then stored in air at 0 °C. After various storage durations, MCP was reapplied at the same or higher concentrations. Control fruit not exposed to MCP were stored at the same temperature in either air or a controlled atmosphere (CA). Reapplication prolonged MCP responses compared to fruit treated only at harvest and fruit quality after storage was similar to that of fruit stored in CA. Reapplication was most effective when fruit ethylene production was below 0.1 μL·L–1 at the time of reapplication. The use of low concentration MCP treatments at harvest may allow for more predictable ripening of fruit after storage, particularly for pear fruit where softening is desired.
'Elberta' peaches (Prunus persica L.) harvested 6 days apart were treated with 0.5 mL·L-1 1-MCP for 4 hours at 20 °C then stored at 0, 5, 10 or 20 °C. Fruit were ripened at 20 °C for 3 days after 1, 3, and 6 weeks of storage at 0, 5, and 10 °C. Treatment with 1-MCP delayed the onset of climacteric ethylene production and reduced respiration in fruit held at 20 °C. 1-MCP-treated fruit were firmer than untreated controls after storage at 0 or 5 °C. 1-MCP-treated fruit also had higher titratable acidity (TA) after 1 week of storage at 0 or 5 °C, but TA was lower compared to controls after 3 or 6 weeks of storage. Fruit stored at 5 °C had more severe internal browning, lower extractable juice and TA than fruit stored at either 0 or 10 °C, however, 1-MCP treated fruit had more severe internal browning than untreated fruit after 3 and 6 weeks of storage at 5 °C. Fruit from harvest 1 treated with 1-MCP and stored at 0 °C for 6 weeks failed to soften after removal from storage. Chemical name used: 1-methylcyclopropene (1-MCP).