IMPACT OF WILD BLUEBERRY FRUIT CHARACTERISTICS AND MACHINE PARAMETERS ON PERFORMANCE OF A MECHANICAL HARVESTER: BASIS FOR AUTOMATION

摘要

Mechanical harvesting of wild blueberries results in fruit losses during manual adjustment of harvester's operations in fields of variable fruit characteristics (fruit yield, fruit zone, and fruit diameter). This study examined the impact of fruit characteristics and machine operating parameters including harvester ground speed (1.2, 1.6, and 2.0 km h(-1)) and header revolutions per minute (26, 28, and 30 rpm) on berry losses. Fruit characteristics were classified into two categories; i.e., fruit zone (LFZ: low fruit zone - average plant height <= 17 cm and HFZ; high fruit zone - average plant height > 17 cm) and fruit yield (LFY ; low fruit yield - average yield <= 3000 kg ha(-1) and HFY; high fruit yield - average yield > 3000 kg ha(-1)). Experimental treatments (ground speed x RPM: 3x3) were randomly replicated thrice under factorial design in four fields at each combination of fruit characteristics (LFZ-LFY , LFZ-HFY, HFZ-LFY , and HFZ-HFY). The fruit diameter was used as a co-variate in this study. With moderate to high variability in fruit characteristics and berry losses within the selected fields, the picking performance of the tested harvester was better in the high fruit zone irrespective of fruit yield at all treatment combinations of ground speed and header rpm. There were lesser fruit losses in high yielding areas at the lowest ground speed and header rpm. The harvester's picking performance was better in high fruit zone areas at a traditional head height of up to 10 cm above ground. However, 5%-15% variations in fruit zone reduced berry picking efficiency at a constant head height. It is concluded that the selection of an ideal combination of harvester ground speed and header rpm based on crop variations in blueberry fields can minimize berry losses during harvesting. The findings of this study would suggest that automation of the tested wild blueberry harvester could improve harvest efficiency.