Controlled-atmosphere Storage of 'Honeycrisp' Apples

'Honeycrisp' is an apple [Malus xsylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] that can be stored in air for several months, but the flavor becomes bland with prolonged storage. Controlled-atmosphere (CA) storage recommendations have not been made in some growing regions, however, because of the susceptibility of fruit to physiological disorders. In the first year of this study, we stored fruit from six orchards in O-2 partial pressures (pO(2)) of 1.5, 3.0, and 4.5 kPa with 1.5 and 3.0 kPa pCO(2). In the second year, we stored fruit from three orchards in three storage regimes (2.0/2.0,3.0/1.5, 3.0/0.5 kPa O-2/kPa CO2) with and without treatment of fruit with 1-methylcyclopropene (1-MCP) at the beginning and end of the conditioning regime (10 degrees C for 7 days) that is commercially used for 'Honeycrisp'. CA storage had little effect on flesh firmness, soluble solids concentration (SSC), and titratable acidity (TA) over the range of pO(2) and pCO(2) tested. Greasiness was generally lower in fruit stored in lower pO(2) and higher pCO(2). Susceptibility of fruit to core browning and senescent breakdown varied between years, but a high incidence of internal CO2 injury in fruit from some orchards occurred in both years. 1-MCP treatment decreased internal ethylene concentration (IEC) and sometimes maintained TA but had little effect on firmness and SSC. Senescent breakdown and core browning incidence were reduced by 1-MCP treatment where orchard susceptibility to these disorders was high. However, 1-MCP treatment sometimes increased internal CO2 injury, especially if treatment occurred at the beginning of the conditioning period. CA storage cannot be recommended for storage of New York-grown 'Honeycrisp' apples until management of CO2 injury can be assured.