Effect of ground speed and header revolutions on the picking efficiency of a commercial wild blueberry harvester

Abstract. The wild blueberry industry is facing increased harvesting losses with the existing commercial harvester. These machines are no longer able to efficiently harvest the higher yields that result from improvements in plant growth and productivity. This study was designed to evaluate the performance efficiency of a commercial wild blueberry harvester for fruit losses during harvesting. Four wild blueberry fields were selected in the Nova Scotia and New Brunswick provinces of Canada. A 3 × 3 factorial experiment was constructed to examine the joint effect of ground speed and header revolution per minute (rpm) on picking efficiency of the harvester. Eighty-one yield plots (0.91 × 3 m) were selected randomly in each field. The field boundaries, bare spots, weeds, and yield plots were mapped with a real-time kinematics global positioning system (RTK-GPS). The harvester was operated at specific levels of ground speed at 1.2, 1.6 and 2.0 km h-1 and header rpm of 26, 28 and 30. The total fruit yield, un-harvested berries on the plants, berries on the ground, and berries through the blower, were collected from each plot within the selected fields. The pre-harvest fruit losses were collected from each plot prior to harvest. The treatment combinations were assigned randomly within the selected fields. The slope, plant height, and fruit zone were also recorded manually from each plot. Results indicated that the pre-harvest fruit losses were lower in early season compared to those harvested later. Un-harvested berries on the plants and losses through the blower were significantly lower than losses on the ground. Significant relationship among the fruit yield and total losses (r = 0.54 to 0.82) suggested that losses during harvesting were proportional to fruit yield. A factorial analysis of variance (ANOVA) showed that ground speed, header rpm, and their interaction were found to have significant (p=0.05) effects on the picking efficiency of the harvester. Results of means comparison showed that a combination of 1.2 km h-1 and 26 rpm resulted in significantly lower losses when compared with other treatment combinations. Results also revealed that a suitable combination of ground speed and header rpm can minimize the fruit losses during harvesting. This can increase harvestable yield and farm profitability.