Marigold (Calendula officinalis) is a medicinal plant that is known and used for centuries. The substances of interest contained in marigold include flavonoids, triterpene and triterpene saponins . Extracts of the drug are used externally for the treatment of mild inflammation of the skin and oral mucous and to promote wound healing. It is regularly cultured on fields with potassium fertilization. The aquaponic production of medicinal plants in combinatio n with African catfish offers the possibility of cultivating medicinal plants under controlled conditions while saving resources. However, its performance under glasshouse cultivation must be demonstrated.
In order to investigate the suitability of aquaponically produced marigolds as medicinal plants, marigolds were cultivated in three experimental groups and triplicates for 57 days in pot culture with perlite/vermiculite. The experimental groups were kept in ebb and flood systems with a regular commercial fertiliser solution (control), process water from intensive catfish aquaculture and process water from intensive catfish aquaculture with additional potassium fertilisation. The flowers were harvested at three points in time, each with a one-week interval between them. The quality of the harvested petals was analysed in accordance with European Pharmacopoeia 10.1.
Significanlty best growth was achieved in the group with intensive process water, followed by intensive process water with potassium and the control group . The first plants reached flowering after 26 days, with similar flowers in all three groups. Analyses of the valuable ingredients demonstrated that content of flavonoids were similar high compared with other commercial plants, reaching levels of about 0.4 % . This study demonstrates that the aquaponics production of marigold in combination with African catfish under glasshouse conditions is possible and that the quality determined compounds reach similar levels required for its use as a medicinal plant .