Influence of Nitrogenous and Phosphatic Fertilizers Types and Rates on the Yield and Chemical Profile of Sutherlandia frutescens and Leonotis leonurus

Abstract

Sutherlandia frutescens and Leonotis leonurus are two important medicinal plants used traditionally to treat diabetes and inflammation harvested mainly from natural resources. The shift from subsistence to commercial trade necessitates research into cultivation, and hence information is needed for commercial production of these species. The effects of nitrogen (N) and phosphate (P) fertilizers in different forms and also at different levels on the growth and yield as well as the chemical composition were investigated. This study reported fertilizer applications' dramatic response on growth and development. The results provide a foundation for more in depth cultivation research and guidelines for soil amendment in increasing yield under field production. For L. leonurus ureum applied at 360 kg N ha-1 resulted in the highest yield. The highest yield for S. frutescens was obtained with ammonium sulphate at 360 kg N ha-1. No significant improvement in yield was obtained with P amendment for L. leonurus while S. frutescens could not survive the P trial conditions and most of the plants died. Thin layer chromatography (TLC) provided an overview of the effect of soil amendment on the chemical profile of the plants with various differences observed on the TLC plates by comparing the sample spots. Incomplete information on the active principles of both species poses various challenges in determining the effect of soil amendment on quality. These results warrant further studies into the effect of the changes in the chemical profile on the medicinal activity of the plants and specifically on target compounds.

The Potential of Rhizobacteria to Mitigate Abiotic Stress in Lessertia frutescens

“…In a similar study, the effect of phosphate and ammonium-based fertilizers on L. frutescens was assessed. Phosphate-based fertilizer was toxic to the medicinal plant, while the application of ammonium sulphate fertilizers resulted in an improved chemical profile [ 91 ]. However, the identity of the specific phytochemicals was not established.…”