ROW SPACING AND THE TERM OF HARVEST OF FLOWER HEADS AS DETERMINANTS OF CROP YIELD AND CHEMICAL COMPOSITION OF RAW MATERIAL OF CHAMISSO ARNICA (Arnica chamissonis LESS.)
Background. The surface area of chamisso arnica cultivation in Poland is very small; however, due to a decline in the natural resources of mountain arnica, and the resulting problems with the acquisition of raw material, the pharmaceutical market has become interested in raw material from chamisso arnica, which could be a substitute for the endangered species A. montana. This fact has underlined the need to conduct research on the cultivation of chamisso arnica so as to be able to refine individual elements of agricultural technology.
Material and methods. In 2015–2017 a field experiment was carried out to assess the impact of row spacing systems (traditional with single rows every 40 cm and a belt cultivation system with four rows with a spacing of 40 cm between each row alternating with an 80 cm wide spacing every four rows; in the case of both spacing systems the distance between plants within a row was 20 cm) and the harvest term (A – yellow bud stage, B – beginning of flowering, C – full flowering, D – end of flowering) on the yield and chemical composition of raw material. Sesquiterpene lactones were determined using the chromatographic method described in Farmakopea Polska VIII (URPLWMPB, 2008). The flavonoids content was determined as quercetin equivalents with the spectrophotometric method and hydrodistillation was applied to determine the percentage of essential oils, as described in Farmakopea Polska VI (URPLWMPB, 2002).
Results. The highest raw material yield was obtained in objects with the traditional spacing system and flower heads harvested at the end of flowering. The harvest term had a significant impact on the concentration and yield of the analysed metabolites. The content and yield of sesquiterpene lactones systematically increased between the yellow bud stage and the end of flowering. The highest contents of flavonoids and essential oils as well as the highest yields of these metabolites were determined in heads harvested at the full flowering stage. The lowest content of all analysed active substances was found in inflorescences harvested in the yellow bud stage.
Conclusion. Row spacing and the date of harvesting flower heads had a significant impact on raw material yields and the content of active substances. Chamisso arnica cultivation in traditional spacing was more favorable due to higher yields of flower heads and yields of sesquiterpene lactones, flavonoids and essential oils.