Suitability of Spanish ‘Manzanilla’ table olive orchards for trunk shaker harvesting

Abstract

Low harvesting efficiency and fruit damage are the main limitations for trunk shakers in the harvesting of table olives. Different cultivations of olive orchards, variations in the fruit properties over the harvesting season, and a wide range of machines both characterise and hamper the harvesting process in several traditional olive producing countries, such as Spain. The aim of the work reported was to develop the mechanical harvesting of existing orchards using commercial trunk shakers maximising the quantity of harvested fruit while maintaining its quality. Results showed that the mean value of harvesting efficiency with trunk shakers was 74%, when additional rod beating or abscission agents were not applied. In orchards where the trees were trained into shapes that facilitated the transmission of vibration, fruit properties had a limited effect on harvesting efficiency. In order to achieve harvesting efficiency >85%, tree trunk vibration parameters were set above an acceleration value of 183.4 m s−2, and at a frequency of 28.1 Hz. Although increasing the trunk acceleration improved harvesting efficiency, it led to an increase in damage to the harvested fruit. Damage caused to the fruit through mechanical harvesting was 3.5 times greater than the damage caused by manual harvesting. Adjusting the vibration parameters, limiting the power of the machine, training the canopy to reduce volume and facilitating the vibration transmission to the fruit, together with effective post-harvest field treatments that maintain the fruit quality, are all required to ensure the success of vibration harvesting systems for green olives.