Effect of shaking location and duration on mechanical harvesting of fresh market apples

With adopting the modern high-density tree architectures, localized shake-and-catch harvesting is becoming more promising for fresh market apples. To investigate the shaking inputs for an effective harvesting system, a multi-tier shake-and-catch harvesting platform was developed and evaluated in a commercial orchard. The platform composes of a shaker and two three-tier catching surfaces. Performance test was conducted in 'Jazz' apple trees trained to a vertical fruiting wall architecture (two horizontal branches at each tier). Two harvesting sections were defined in the test trees, namely, Section I - two neighboring branches at the same tier from two adjacent trees; and Section II - two branches at the same tier of a tree. For Section I, shaking was applied to the middle of each branch (location P1), and for Section II, shaking was applied at the location close to the trunk (location P2). Shaking frequency was set to 20 Hz, and two shaking durations (i.e., 5 and 2 s) were used. In the test, the catching angle relative to the horizontal plate was set to 15°. The results indicated that the fruit removal efficiencies (2nd to 4th tiers of trees were used in the analysis) were 76.6% and 78.1% for shaking at middle of each branch in 2 and 5 s shaking, respectively; those numbers were 86.3% and 89.5% for shaking at location P2. The percentage of marketable fruits were 89.7% and 90.6% for the Section I shaking in two durations, and 84.5% and 84.4% in the Section II shaking. Overall, this study revealed that 2 s shaking duration is sufficient to remove majority of fruits in the tested variety, and the section II shaking had higher overall fruit removal efficiency but also caused slightly more fruit damage.