The evaluation of quantitative characteristics and essential oil composition of Calendula officinalis L. affected vermicompost and humic acid

The application of organic fertilizers has a vital role in improving the quantitative and qualitative characteristics of medicinal plants. Calendula officinalis L. is an important medicinal plant from the Asteraceae family. Its extract has medicinal effects such as wound healing, anti-inflammatory, blood purifying, and antibacterial and contains essential oils, carotenoids, and amino acids. This experiment was conducted in a completely randomized design with six treatments and three replications to investigate the effect of humic acid and vermicompost on some quantitative characteristics and essential oil composition of Calendula officinalis L. in the research greenhouse of the University of Nahavand in 2019. Treatments include control, vermicompost fertilizer in two levels of 100 and 200 g and humic acid in two levels of 0.5 and 1 g.L-1, and integrated treatment of 100 g vermicompost and 0.5 g.L-1 humic acids. The results showed that the highest amount of phenol was produced in the integrated treatment of humic acid and vermicompost. The highest percentage of essential oil (0.32%) was obtained in the integrated treatment of humic acid and vermicompost. Twenty-eight compounds were observed in essential oil, in which alpha-Cadinol had the highest amount. Also, the highest level of alpha-Cadinol was obtained in the integrated treatment of vermicompost and humic acid. It can be said that the use of organic fertilizers can be effective in improving the quantitative characteristics of marigold flowers.