A review of different cultivation protocols for the conservation of Lessertia frutescens (L.) Goldblatt & J.C. Manning

Abstract

• Propagation is a viable strategy to supplement natural populations of L. frutescens . • Rhizobia inoculation supports sustainable conservation of L. frutescens . • High cost and complexity make micropropagation less feasible for L. frutescens . • Future research should focus on selecting superior rhizobia strains. Lessertia frutescens (L.) Goldblatt & J.C. Manning is a medicinally and economically valuable plant endemic to South Africa. Recent renewed interest in its therapeutic potential has underscored the urgency of its conservation efforts. The wild populations, which are the current main source of raw materials, may decline to a point of extinction due to overharvesting. The prospects of the wild populations necessitate the implementation of conservation strategies to mitigate the decline. Cultivation emerges as a viable strategy to supplement dwindling natural populations and support conservation initiatives. This paper evaluates various cultivation protocols for L. frutescens, highlighting their limitations and potential for sustainable application. The protocols include the application of plant growth-promoting rhizobia; foliar application of plant extracts; micropropagation; chemical fertilization; application of exogenous phytohormones, as well as endophytes. Among these, micropropagation was the most commonly investigated technique. However, its high cost and technical complexity limit its widespread use. While nitrogen-based chemical fertilizers show moderate efficacy, their environmental implications render them unsuitable for sustainable cultivation. Notably, plant growth-promoting rhizobia emerge as the most promising and ecologically sustainable alternative for enhancing the cultivation and conservation of L. frutescens. Although some challenges remain in optimizing this approach, they can be addressed without compromising its environmental integrity. It is recommended that future research prioritizes the selection of superior strains and field-based evaluations of promising rhizobial strains to develop them for formulation and deployment as bioinoculants.