UC Davis

Olives (Olea europaea L.) produce abundant flowers, but only a small subset persist as fruits. We hypothesize that the low fruit set to flower ratio is due to the short ovule longevity. Ethylene inhibition is hypothesized to prolong olive inflorescence longevity, extending the effective pollination period (EPP) and improving yield. The objective of this research is to determine whether applying exogenous aminoethoxyvinglglycine (AVG, an ethylene inhibitor) during bloom will decrease ethylene generation and increase the EPP, fruit set and yield. A 264 ppm ReTain™ (a.i. Aminoethoxyvinylglycine) sprayed at bloom on Arbequina olives and monitored through the end of bloom significantly reduced ethylene production but did not affect visual bloom senescence or pollen tube growth, measured by pollen tube width. At harvest, fruit yield was measured, and the oil analyzed. ReTain™ bloom application did not delay flower senescence or improve pollen tube growth. It significantly reduced ethylene generation and mildly increased fruit yield, but the yield increase was not significant. The collective results show that ReTain™ can significantly and strongly decrease ethylene generation in Arbequina olive flowers, but not extend flower longevity, improve fruit set or yield. Heavy rain, accompanied by low temperatures, during the bloom may be the reason why the flower longevity was not extended, resulting in decreased fruit set.