Regulating Ripening of ‘Bartlett’ Pears Using Preharvest Plus PostharvestAminoethoxyvinylglycine (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 fur- ther 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 oC. In- ternal 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.