Influence of comb parameters on picking properties for chamomile flowers (Matricaria recutita)

Tools in the form of a comb are generally used to harvest chamomile flowers. The combs can be hand-operated or machine-based. To achieve good picking quality and low losses, the comb parameters have to be optimized. In this paper, the influence of comb thickness (0.5 mm, 1.0 mm and 2 mm) and the shape of the gap between the tines (3 variants) on picking force and remaining stalk length was investigated for German chamomile (Matricaria recutita) under lab conditions. To ensure that the stalks glide along the gap to the ground of the picking blade, the inclination angle was adjusted to be 45° from the blade plane in the direction of movement. For each of the 9 variants, 100 breaking tests were performed. To estimate the breaking force, a specific tensile force measuring instrument was used. The mean breaking strength of the stalks for the investigated 9 variants ranged from 3.62 N mm−2 to 4.66 N mm−2. In about 50% of the tests, the comb parameters had no influence because stalks broke outside of the contact point with the comb at the weakest section of the stalk. In conclusion, the picking quality of involved test blades was partially influenced by the thickness of the blade, the shape of the gap between the teeth and substantially by the strength of the individual chamomile stalks.

Research highlightsInvestigations under lab conditions were performed for optimizing of picking comb parameters on harvesters for chamomile flowers. It was shown that both the picking tool parameters and the individual stalk strength influenced the results.