Regulating Ripening of Bartlett Pears Using Preharvest Plus Postharvest Aminoethoxyvinylglycine (AVG)

In many deciduous fruit growing regions of the world, because of such factors as lack of chilling hours during winter followed by protracted anthesis, variation in fruit maturity and ripening uniformity of Bartlett (Pyrus Communis) pears is troublesome. Such variability makes timely harvest difficult, especially when labor is insufficient. Use of ReTain (aminoethoxyvinylglycine, AVG, Valent Bioscience, Walnut Creek, CA) applied 4 weeks before harvest has mitigated this somewhat by delaying maturity development in treated blocks, thereby providing multiple harvest windows. To further regulate ripening of ReTain -treated Bartlett pears in cold storage, fruit were treated immediately after harvest by dipping fruit in aqueous solutions containing AVG at 0, 66, 132 or 264 mg·l-1 and then kept in regular storage at -1 °C. Internal ethylene concentration of individual fruit was measured at harvest and monthly thereafter for 4 months. During the first 3 months in storage, ethylene production was well correlated with total (foliar plus dip) AVG applied. Treating Bartlett pears after harvest with AVG appears more efficacious in reducing ripening variability during regular storage such that subsequent increase in ethylene is both consistent and predictable.