NITROGEN FERTILISER REQUIREMENTS OF THE SOUTH AFRICAN MEDICINAL PLANT LEONOTIS LEONURUS USED IN TRADITIONAL HEALING PRACTICES
Leonotis leonurus is also known as wild dagga, lebake (Sotho, Tswana) or wilde dagga (Afrikaans). This plant with its attractive orange flowers can grow up to five meters high. The whole plant is strongly aromatic. The leaves and roots are used to treat coughs, colds, influenza, high blood pressure, headaches and bronchitis. Little or no information is available on cultivation of South African medicinal plants. To resolve this, research is conducted to determine the effects of cultivation on the yield and medicinal properties of the plants. The fresh mass yield was recorded and the changes in chemical composition were determined by chromatographic methods and performing bioassays after the plants were fertilised with three different inorganic nitrogen fertilisers. Limestone ammonium nitrate (LAN), ureum and ammonium sulphate was used as fertiliser treatments at 0 (control), 180, 240, 300 and 360 kg N/ha. The recommended fertiliser application was determined to be 180 kg N/ha ammonium sulphate with a yield of 34.4 t/ha fresh mass. The plant material was extracted and subjected to general screening on two gram positive human pathogens namely Enterococcus faecalis, Staphyllococcus aureus and one gram negative bacterium Escherischia coli to determine the effect on the biological activity. Only minor changes were observed in the chemical composition and the Minimum Inhibitory Concentration (MIC) of the extracts against the microorganisms. These differences are probably due to natural variation that exists in the plants as the medicinal properties were not compromised.
Prinsloo, G., Viljoen , J.C. and Du Plooy, C.P. (2011). NITROGEN FERTILISER REQUIREMENTS OF THE SOUTH AFRICAN MEDICINAL PLANT LEONOTIS LEONURUS USED IN TRADITIONAL HEALING PRACTICES. Acta Hortic. 925, 221-228
cultivation, LAN, ureum, ammonium sulphate, bioassay, chromatography