Effect of AVG and MCP on Volatile Production of `Gala' Apple

Abstract

Our goal was to determine how aminoethoxyvinylglycine (AVG) and 1-methylcyclopropene (MCP) interact to influence postharvest storability and volatile production of `Gala' apple. In 2004 and 2005, AVG was applied to `Gala' apple trees 4 weeks before harvest. After harvest, control and AVG-treated fruit were treated for 20 h at 30 °C with MCP, and fruit were ripened at ambient temperature immediately after harvest, after MCP treatment, or after storage at 4 °C for 6 and 12 weeks. For both seasons, control fruit reached the highest internal ethylene concentration (IEC) during ripening at ambient temperature immediately after harvest. After storage, control fruit had very low IEC in 2004, but the highest in 2005. In general, the combined treatment repressed ethylene production the most for all harvest dates and lengths of storage. AVG plus MCP-treated fruit consistently had the highest flesh firmness (FF) but also had the lowest total volatile production (TVP) by flesh or peel after 6 and 12 weeks in cold storage following both harvest dates. The activity of alcohol acyltransferase was affected by the treatments, but could not explain all the variation found in TVP. TVP was lower for flesh than peel of control and treated fruit, but feeding alcohol substrates to the fruit resulted in a significant increase in TVP, regardless of tissue type or treatment. The results indicate that the combination of AVG plus MCP maintained apple fruit FF in cold storage better than the treatments used alone, but also substantially reduced TVP. Substrate availability seemed to be the most limiting factor affecting TVP by flesh and peel of `Gala' apples treated with AVG plus MCP.