YIELD AND THE CHEMICAL COMPOSITION OF FLOWER HEADS OF POT MARIGOLD (Calendula officinalis L. cv. Orange King) DEPENDING ON NITROGEN FERTILIZATION

Marigold belongs to the oldest medicinal plants, which had been used in the ancient times. At present it supplies its material of a great significance for pharmaceutical and cosmetic industry. The study was conducted in the period 2007–2009 on loess soil with the granulometric composition of silt loam. The aim of the experiment was to determine the effect of different nitrogen doses (0, 40, 80, 120, 160 kg N·ha) on some plant morphological features as well as on yield and quality of pot marigold inflorescences. Flowering of pot marigold was shortest in the control treatment (30 days) and longest (40 days) in the plot where nitrogen fertilization had been applied at the highest rate (160 kg N·ha). Nitrogen fertilization had a significant impact on the number of flower heads per plant, but no differences were found in inflorescence diameter under investigated factor. Raw material yield was found to increase significantly after the application of 80 kg N·ha, compared to the control treatment. Further increase in the amount of nitrogen (120, 160 kg N·ha) did not result in growth of yield. Nitrogen fertilization modified essential oil content in flowers heads (this content increased along with increasing nitrogen rates), but it did not affect the percentage of flavonoid compounds.