Storability and fruit quality of 'golden delicious' as affected by harvest date, AVG and 1-MCP treatments

The effects of preharvest AVG and postharvest 1-MCP treatments on 'Golden Delicious', clone 'Reinders' apples (Malus domestica cv. 'Golden Delicious') stored in controlled atmosphere (CA) were studied during the 2003/04 growing and storage season. Retain™ (15% a.i.) was used as AVG source, and AVG treatment (125 ppm) was applied 4 weeks before optimal harvest date (OHD). Fruits were harvested at three different stages of maturity (OHD, OHD + 1 week, OHD + 2 weeks). After harvesting, the fruits of each stage of maturity (ca. 40 kg) were divided in two samples. One sample was treated with 1-MCP 625 ppb, the other one remained untreated. After treatment the samples were stored for approximately 270 days under CA conditions (temperature 1.0°C, O 2 1.5%, CO 2 3.5%). Preharvest sprays of AVG delayed ripening for about 7 days and retarded postharvest ripening during CA-storage. Whereas AVG and 1-MCP untreated fruits showed excessive firmness losses and reduction of titratable acidity during shelf-life, AVG and 1-MCP delayed softening and stabilised titratable acidity. These effects were related to the stage of maturity, and a significant synergistic effect of AVG and 1-MCP on fruit quality was observed. Fruits in a stage of over maturity lost more in firmness and acidity than fruits harvested at their optimal stage of maturity. Total soluble solids (TSS) were also affected by AVG and 1-MCP treatments positively. Fungal decay, CO 2 damages and senescent scald were the main problems after long term storage. The ability of 1-MCP to reduce fungal decay varied considerably among the stage of maturity. If apples, harvested too late, were treated with 1-MCP, only very little or no response occurred. AVG treatments strongly reduced fungal decays (from 18.4 to 3.4%) by delaying ripening. Overripe fruits treated with 1-MCP additionally showed a higher incidence of internal browning disorders (brown core, flesh browning, cavities) and scald. These fruits should be excluded from 1-MCP treatments. 1-MCP treated fruits tended - independent of the stage of maturity - to be more susceptible to higher CO 2 concentrations than the untreated.