'Law Rome' and 'Golden Delicious' apples differ in their response to preharvest and postharvest 1-methylcyclopropene treatment combinations.

TLDR: Findings suggest that attached apple fruit of some cultivars may be capable of rapidly generating new ethylene receptors as determined by flesh firmness, starch index, internal ethylene concentration, and soluble solids concentration.

Abstract: Experiments were conducted to compare the effects of different preharvest and postharvest 1-methylcyclopropene (1-MCP) treatment combinations on 'Law Rome' and 'Golden Delicious' apple fruit. Preharvest 1-MCP sprays had minimal effects on maturity as determined by flesh firmness, starch index, internal ethylene concentration, and soluble solids concentration. Fruit internal ethylene concentration and firmness loss after 30- to 40-days storage at 0 °C plus 7 days at 20 °C were reduced by preharvest and postharvest 1-MCP treatments. The positive effects of preharvest 1-MCP on postharvest quality of 'Law Rome' declined in fruit that were harvested 3 days or more after spraying, whereas preharvest 1-MCP continued to have a positive effect on postharvest fruit quality of 'Golden Delicious' that were harvested up to 9 days after spraying. The loss in postharvest effects of preharvest 1-MCP treatment on 'Law Rome' at delayed harvests was reinstated by exposing fruit to gaseous 1-MCP on the day of harvest. These findings suggest that attached apple fruit of some cultivars may be capable of rapidly generating new ethylene receptors.