Fruit Maturity Based on IAD Values in Relation to Preharvest 1-Methylcyclopropene Treatment and Postharvest Physiological Disorder Development in ‘Honeycrisp’ Apples

‘Honeycrisp’ apples are prone to physiological disorder development during storage, fruit susceptibility to disorder incidence being affected by harvest date. The effects of fruit maturity from untreated trees and those sprayed at 1 week before the first harvest with 1-methylcyclopropene (1-MCP; Harvista TM ) were investigated by categorizing fruit into index of absorbance difference ( I AD ) values before storage. Maturity indices, chlorophyll, carotenoid, and sugar concentrations were assessed at harvest. The incidences of physiological disorders were assessed after 4 months plus 7 days at 20 °C. The internal ethylene concentration and the starch pattern index were lower in fruit treated with preharvest 1-MCP compared with untreated fruit, while fruit firmness was higher in preharvest 1-MCP–treated fruit. The difference was more pronounced in fruit with higher I AD values (higher chlorophyll) categories at harvests 2 and 3. Chlorophyll a and total chlorophyll concentrations were positively correlated with the I AD values in both untreated and preharvest 1-MCP–treated fruit. Acetaldehyde and ethanol were unaffected by harvest time, but preharvest 1-MCP–treated fruit had lower ethyl acetate accumulation at all harvests. Sucrose, fructose, glucose, galactose, sorbitol, and malic acid concentrations were often higher in preharvest 1-MCP–treated fruit than in untreated fruit. Soft scald incidence was higher in fruit with lower I AD values. However, the disorder was lowest in harvest 1 and 2 fruit of higher I AD values when the fruit were treated with preharvest 1-MCP. Additionally, fruit senescence was higher in late-harvested fruit. Principal components analysis, multivariate analysis, and the nonlinear iterative partial least square algorithm showed that fruit physiological disorder development after storage was correlated with fruit maturity based on the I AD value and maturity at harvest as affected by preharvest 1-MCP treatment.