- To optimize storage quality of 'd'Anjou' pears (Pyrus communis L.) produced in the US Pacific Northwest regions, the recommended harvest maturity as indicated by flesh pressure is 67 to 58 N. Over-mature pears are more susceptible to superficial scald and inferior eating quality after storage. However, a significant portion of pears is harvested at an over-mature stage due to rapid on-tree maturation during years with labor shortages. 1-Methylcyclopropene (1-MCP) extends storage quality of pears but interferes their ultimate ripening capacity. The purpose of this work was to evaluate the effect of 1-MCP on over-mature 'd'Anjou' pears. Fruit from two orchards at fruit firmness (FF) 55.6 and 56.0 N were treated with 0.15 mu L L-1 1-MCP, held at - 1.1 A degrees C for up to 7 months. 1-MCP treatment significantly inhibited ethylene synthesis and respiration rate, reduced superficial scald, and maintained high storage quality of over-mature pears from two orchards during 7 months of storage. After 7 months of storage at - 1.1 A degrees C, some of the pears from Orchard 1 recovered ripening capacity after 5 days at 20 A degrees C. The development of superficial scald in over-mature 'Anjou' pears was associated with the accumulation of alpha-farnesene and conjugated trienols (CTols). 1-MCP significantly inhibited the development of scald, perhaps by alleviating membrane lipid peroxidation and enhancing total antioxidant capacity, antioxidant metabolites (i.e., total polyphenols (TP) and total flavonoids (TF)), and related enzyme activities (i.e., superoxide dismutase (SOD), catalase (CAT)) in pear skin. Overall, this study provides the preliminary basis for commercial application of 1-MCP in over-mature pears and demonstrates its potential to maintain fruit quality and reduce the incidence of superficial scald.