Preharvest AVG Applications Improve Storability of Summer Pears Depending on Application Rate, Timing, and Harvest Maturity

‘Bartlett’ and ‘Starkrimson’ summer pears (Pyrus communis L.) have a characteristically short storage life due to increased ethylene production induced by cold storage. A recent trend toward greater fresh market utilization of ‘Bartlett’ and an increased export demand for ‘Starkrimson’ necessitate extended storage life due to a prolonged packing and marketing season. The effects of preharvest aminoethoxyvinylglycine (AVG) spray rate and timing on storability of ‘Bartlett’ fruit at three harvest maturities [H1: when control fruit firmness (CFF) ≈ 83.6 N; H2: 12 days after H1 when CFF ≈ 74.8 N; and H3: 17 days after H1 when CFF ≈ 72.6 N] and ‘Starkrimson’ harvested once [CFF ≈ 60 N] were evaluated with respect to ethylene production, storage quality, and ripening capacity during 5 and 4 months of storage at –1.1 °C, respectively. For ‘Bartlett’, AVG at 60 mg·L^-1 applied 1 week before H1 (WBH1) suppressed ethylene production and respiration rate, retarded fruit firmness and green color loss, and reduced senescence disorders while maintaining ripening capacity of H1 and H2 fruit. Compared to 60 mg·L^-1, AVG at 120 mg·L^-1 applied 1WBH1 did not improve storage quality but did delay ripening capacity by one month. AVG at 30 mg·L^-1 applied 1 WBH1 and 120 mg·L^-1 applied 2 WBH1 had little effect on any of the storage responses measured. Ethylene production and storage quality of H3 fruit were not affected by AVG, irrespective of rate. AVG at 60 and 120 mg·L^-1 applied 1 WBH1 and 120 mg·L^-1 applied 2 WBH1 did not affect initial harvest maturity (H1) but did delay pre-harvest fruit maturation of H2 and H3 fruit by about 5–7 days. The response of ‘Starkrimson’ to AVG was similar to ‘Bartlett’ (i.e., inhibited ethylene production, maintenance of fruit firmness, and reduced senescence disorders during 4 months of storage at –1.1 °C). These results suggest that appropriate preharvest AVG applications extend the harvest window of ‘Bartlett’ and ‘Starkrimson’ and reduce storage losses during extended packing and marketing.