Fruit Quality Attributes of ‘Arisoo’ and ‘Picnic’ Apples as Influenced by 1-Methylcyclopropene Concentration and Its Application Frequency during Cold Storage

The efficacy of 1-methylcyclopropene (1-MCP) in maintenance of apple fruit quality can differ depending on apple cultivar, ethylene content at harvest, 1-MCP concentration, the interval between harvest and 1-MCP application, and the number of applications. In this study, we investigated whether the 1-MCP concentration and its application frequency differently affected fruit quality attributes of the two new apple cultivars ‘Arisoo’ and ‘Picnic’. The fruits were treated with 1-MCP (as single or double treatments) at the rate of 0 μL L−1 (control), 0.5 μL L−1, 1 μL L−1, 0.5 + 0.5 μL L−1, and 1 + 1 μL L−1 for 18 h, and they were stored at 0 °C up to six months. Comparatively, the fruit qualities of 1-MCP treated fruits were higher than that of the control during cold storage, with a higher suppression of internal ethylene content and a slower reduction of titratable acidity in 1-MCP treatments than the controls throughout the cold storage in both cultivars, regardless of the concentration and number of applications. Reduction of fruit firmness and soluble solid contents were maintained by single application of 0.5 μL L−1 1-MCP in ‘Arisoo’ apple, while double application of 0.5 + 0.5 μL L−1 was needed in ‘Picnic’ cultivar. The effective concentration for weight-loss reduction was found to be the single application of 1 μL L−1 1-MCP in both ‘Arisoo’ and ‘Picnic’. Conclusively, 1-MCP as single treatment at the rate of 0.5 μL L−1 could be sufficient in inhibiting ethylene action and maintaining fruit quality losses during cold storage, particularly in ‘Arisoo’. However, double application of 1-MCP might be necessary for some quality attributes in ‘Picnic’ apple.