The Effects of Aminoethoxyvinylglycine on Fruit Set in Emasculated, Hand-Pollinated Sweet Cherry (Prunus Avium L.)

Abstract

Fruit set of sweet cherry is low when utilizing emasculated, hand-pollinated blossoms, as part of a breeding program. The ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) has been shown to increase fruit set in sweet cherry and has been approved for commercial use for this purpose. We investigated the ability of AVG to increase fruit set in emasculated, hand-pollinated blossoms over two crossing seasons. AVG was applied to blossoms either the day before or the day of emasculation, and the blossoms were pollinated the day after emasculation. Fruit set was evaluated when the cherries were still green, but after the natural abscission (‘June drop’) of unsuccessfully fertilized blossoms had occurred. Mixed model analysis showed no significant treatment effect on fruit set, but a significant cross effect was observed. Comparison of treatment effects within individual crosses was performed using Fisher’s exact test. A wide range of effect was observed, including a negative effect on fruit set in several crosses when treated with AVG the day of emasculation, especially in 2019. When a positive effect of AVG was observed for a given cross, treatment the day before emasculation was more effective on fruit set than treatment the day of emasculation. In general, treatments with AVG produced a more positive effect in 2020 when more freeze damage occurred. AVG may have inhibited senescence of partially damaged blossoms, allowing fertilization and fruit set to occur. In summary, AVG can be used to increase fruit set in emasculated, hand-pollinated sweet cherry crosses, but it must be evaluated on a cross-by-cross basis, and the data suggest a greater effect when applied one day before emasculation.