Physiological Disorder Development Of 'Honeycrisp' Apples After Pre- And Post-Harvest 1-Methycyclopropene (1-Mcp) Treatments

Susceptibility of apple fruit to physiological storage disorders is affected by both pre-and postharvest factors that influence their ethylene production. In this study, the inhibitor of ethylene perception, 1-methycyclopropene (1 MCP), applied before and after harvest, has been used to investigate the interactions between ethylene and development of physiological disorders in 'Honeycrisp' apples during storage. Preharvest 1-MCP (HarvistaTM) was applied to trees, either 2 weeks (early), 1 week (late), at 1 and 2 weeks (repeated), or at double rate 1 week, before first commercial harvest. Fruit were then untreated or treated with postharvest 1-MCP (SmartFresh (R)) and stored at 0.5 degrees C, or conditioned at 10 degrees C for 7 d and then stored at 3 degrees C (C + 3 degrees C), for 20 weeks. Fruit quality and physiological disorders were assessed after 4 d at 20 degrees C. Fruit from all preharvest 1-MCP treatments had lower internal ethylene concentrations (IECs) and were greener as indicated by higher IAD values compared with untreated controls, while effects on starch pattern indices (SPI) were inconsistent. After storage, preharvest 1-MCP-treated fruit were firmer than untreated fruit, but effects of the different application timings were inconsistent. Effects of postharvest 1-MCP on IEC and IAD values were greater at 0.5 degrees C than at C + 3 degrees C. High incidences of core browning and vascular browning developed during storage, especially in the preharvest 1-MCP-treated fruit. Soft scald was reduced by preharvest 1-MCP treatments compared with control. In the C + 3 degrees C storage treatment, preharvest 1-MCP-treated fruit had a higher bitter pit incidence than in control fruit, but less skin wrinkling and senescent breakdown. Postharvest 1-MCP treatment of preharvest 1-MCP fruit slightly decreased bitter pit incidence while greatly increasing that of core browning and leather blotch, and sometimes flesh browning and carbon dioxide injury. This study shows that pre-and postharvest inhibition of ethylene perception by 1 MCP can have marked effects on storage disorders that are affected by fruit maturity and storage temperatures.