Graph 1. Frequency distribution of plucking force
Modern drug industry uses essential oils, which are made from fresh or dry flowers of chamomile. Native sorts of chamomile were harvested by hand long years ago. Now cultivated sorts of chamomile are harvesting by machines with technology based on stripping process.
In this paper object of our research is tractor drawn universal picking machine for medicinal plants named UMLB-2K. Working quality and exploitation parameters were observed in dependence of machine's regime and crop conditions. Crop conditions included plant density, average height of plant, plucking force and number of flowers per plant. Plant density was 2020/m2 and average height was 0.95 m. Average force for tearing off each of 12 flowers per a plant was 4.3 N. Losses were measured in dependence of working speed. Working quality was expressed by percentages of fractions in picked material. In a sample there were: flowers torn off with stems shorter than 4 cm in about 43.8%, with stems longer than 4 cm in 27.6%, damaged flowers for about 28.2% and minor percentage of a weeds 0.4%. Estimated working speed was between 1.35-1.44 km/h.
Key words: picking, chamomile, flower, universal stripping harvester, quality, losses.
Chamomile production requires some operations, which needs to be done in optimal terms. Earlier investigations found out that in this production there were several critical operations. Here is a list of those operations: soil preparation, sowing, harvesting and drying.
In this article harvesting flower of chamomile has been shown as a process which needed special attention. This process has to fulfill some high level demands. Flowers picked with stems no longer than 20 mm are considered as a first class picked material. Flowers picked with stems between 20 and 40 mm are known as a second-class material. Here are also flowers with stems longer than 40 mm and it is called "pulvis". Increasing quality of harvesting means having higher percentage of first and second-class picked material.
Objective of this research was to determine working quality and losses of universal tractor drawn picking machine for chamomile under extreme conditions. Crop height and its density exceeded ordinary figures and most of crop laid down.
This research was performed in 1998 in field experiment in location at farm "Dobričevo" in the area of town Ćuprija. Object of our experiment was semi-mounted tractor drawn universal picking machine observed in harvesting flower of camomile. Activ organ in this process is stripping rotor. Rotor has been assambled on a shaft and it was consisted of 12 finger carriers with 32 fingers. Rotor speed was 220 rpm.
Crop condition was determined in 3 samples diagonnaly taken from the field. Average height, plucking force and number of flowers per plant were measured in this samples. Force needed for tearing off a flower was measured by mechanical dynamometar. Crop humidity was defined measuring weight samples before and after drying.
Crop condition was described with: plant number, number of flowers per plant, height of the lowest and highest flowers and force needed to tear off flower of chamomile. These parameters were registered measuring samples taken from 1 m2 and then it was used in calculation for their average values.
In general chamomile is plant which characteristic is to spread branches, which started almost from the ground forming a dense canopy with number of stems per m2 between 1740-2210 stems/m2 and its average value was 2020 stems/m2. Causes for this density were found in higher germination than in declaration lists for sowing material and higher amount of mineral fertilizer and compost, which exceeded recommended doses. Heights of the highest and the lowest flowers were measured because of their significance for crop suitability for mechanized harvesting. Average values were calculated in each sample. Intervals between the lowest and highest flowers were from 15 to 32 cm and this variation was high. Bigger variation was noticed in a number of flowers per a plant and it was in between 6 and 27 flowers per plant.
Plucking force measuring were obtained considering 100 flowers from the top and 100 from the lower parts of a plant. Plucking force for top flowers was from 3.3 to 8.2 N. Opposite this the lowest flowers resisted to stripping process by force from 1.6 to 5.3 N. Frequency distribution of this force was shown in Graph 1. Calculated average value for both of them was 4.3 N. Moisture content in picked material was 78.3%.
Following exploitation parameters were registered in harvesting flower of chamomile: working speed, working width and efficiency. Variations were made inside one gear speed by adjusting engine speed from 1400, 1600 and 1800 rpm. Estimated working speeds were v1-1.35 km/h, v2-1.44 km/h and v3-1.58 km/h. Theoretically working width was 1.42 m but its effective average value was 1.2 m. Under this conditions machine had efficiency 0.11-0.13 ha/h.
In each speed variations it was needed to determine percentage of losses. Losses were separated in two categories: backward flowers on plants (losses a) and flowers picked but felt onto the ground (losses b). Total losses according to number of flowers left behind machine, were expressed in percentages under different speed values v1- 28%, v2-35% and v3- 47%.
Higher working speed increased percentage of uncollected flowers on plants. Lower speed raised frequency of flowers picked but felt onto the ground.
Working quality of stripping machines is defined by a structure of picked material. It is known that some reasonable expectations about mechanized harvesting are to collect material with stems no longer than 40 mm in 60% and with acceptable level of losses about 8%. Results obtained in this research could not fulfil this demand. Like it was previously said losses were high above this acceptable values. During this research first and second class picked material were shown in total percentages as one fraction and their percentage was 43,8% which confirmed that results were worse than expected in ordinary crop canopy. All above mentioned about crop condition was the reason why this standards were unreachable. Flowers with stems longer than 40 mm were represented in 27.6% damaged flowers in 28.2% and minor percentage of weeds 0.4%.
During this research some exploitation parameters were estimated. Working speed was measured and it was in between 1.35-1.44 km/h. Working width was 1.2 m and its efficiency was 0.11-0.12 ha/h.
Losses were represented with backward flowers on plants and flowers picked but felt onto the ground. Increased losses were consequence of an enormous plant density (average stems number 2020/m2), which brought crop to be flattened. Percentage of losses was high and it was related to working speed from 28-47%.
Working quality was expressed by percentages of fractions in picked material. In a sample there were: flowers torn off with stems shorter than 4 cm about 43.8%, with stems longer than 4 cm in 27.6%, damaged flowers for about 28.2% and minor percentage of a weeds 0.4%.
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