Comparison of damages on three olive cultivars (Olea europaea L.) at different mechanized harvesting methods

Abstract
Background and objectives:
Selection of the best olive harvesting method has a high effect on harvest efficiency and reduction of damage to olive fruits and trees. On the contrary, improper harvest method reduces the next year’s fruit bearing. At harvest time of olives, extensive gardens, diversity of varieties in a garden, high cost and shortages of labour at harvest time, makes mechanical harvesting methods necessary. Thus an experiment in 2015 was performed in a garden at Ramian city to determine the best olive cultivar and harvest method for mechanized harvesting.
Materials and methods
At this experiment, harvesting efficiency and damage on three olive cultivars crops (Mari, Valanolia and Zard) by four types of harvesting methods (Knocking by a wooden rod, branch shaker machine, plastic comb shaker machine and portable branch shaker) were studied in a split plot experiment with three replications.
Results
Analysis of variance showed that the amount and percentage of lost leaf and damaged fruit to harvested fruit ration and damage index is significant to variation cultivar and harvest method as well as interactional effect of the this variables (P≤0.01). The results indicated that the most harvesting efficiency among cultivars were related to the Mari (81.80%) and among harvesting methods, the portable branch Shaker had the most harvesting efficiency (88.20%). At all harvesting methods, the least damage percentage was observed on the Valanolia cultivar and most damage was seen on zard cultivar. The hand held pneumatic vibrating combs caused the most and least damaged fruits on Zard and Valanolia cultivars (45.32% and 7.03% respectively). Zard cultivar had shown the most damage index in harvesting by Knocking by a wooden rod (76.29%) and the Valanolia cultivar had the least damage index in harvest by plastic comb shaker machine (12.32%). Damage index of these cultivars were measured 54.12% and 23.03% correspondingly. Damage index of pneumatic vibrating combs on Zard cultivar had second rank (74.92%) and didn’t showed a significant difference with Knocking by a wooden rod. Damage index of Valanolia and Mari cultivars in harvest by knocking a wooden rod was significantly higher than other harvest methods. At harvest of Valanolia cultivar by plastic comb shaker, the least damage index was observed and Valanolia cultivar had least damage index in harvest by all four methods in comparison to the other two cultivars. Valanolia cultivar had the most leaf drop in harvesting by Knocking by a wooden rod (10.77%). Mari and Zard cultivars showed 8.21 and 7.58% of lost leaf percentage to harvested fruit ratio at this harvest method. The most leaf drop was observed at harvest by knocking a wooden rod. Harvest by the pneumatic branch shaker caused the least leaf drop and no significant difference in leaf drop had observed at harvest by this machine among cultivars.
Conclusion:
Because harvesting efficiency of portable branch shaker was more than the other methods, this method is more suitable for mechanized harvesting. Due to high damage level, knocking a wooden rod is not suitable and leads in reduction of oil quality and produced conserve.