Many traditional healing systems are based on natural biological resources, and there is a general shift in most parts of the world towards natural medicine, with direct implications on the demand and supply of medicinal plants. This review highlights the economic importance of medicinal plants, their contribution to healthcare systems, and potential opportunities for rural economic development through cultivation. A systematic literature review with specific search terms related to medicinal plants was used to collect scientific and non-scientific information from peer-reviewed literature and grey literature databases. The findings indicate that trade in medicinal plants is increasing, and although they are considered minor crops compared to major food crops, their value is among the highest in the list of traded plants globally. The trade also serves as a revenue source for many rural livelihoods, with women playing a significant role. Medicinal plants contribute to primary health care in many developing countries, and they are also an essential source of modern drug discovery. Cultivation of medicinal plants offers emerging rural farmers an opportunity to grow these plants as new and alternative crops, thus reducing unsustainable wild harvesting and competition with established commercial farmers who mostly focus on food crops. Furthermore, medicinal plant cultivation should be promoted as one of the options for local economic development and sustainability through job creation, the revival of the rural economy, and income generation for small businesses, such as the transport businesses, involved in the value chain. Land accessibility, financial resources, and direct market access for rural communities can elevate their contribution to the industry. Formalisation of the lower levels of the medicinal plant trade is also recommended. Significance: Cultivation is a viable option for biodiversity conservation of medicinal plants and ensuring a goodquality supply of plant materials. Cultivation of medicinal plants – a source of natural products used in product development – can contribute to job creation, income generation, and rural economies in developing countries. This review underlines the importance of medicinal plants in product development, the contribution of the industry to economies of different countries, and the potential for cultivation.

Water stress is the most limiting factor in agricultural productivity in arid and semi-arid regions and causes very high losses in crop yield. Regulation of growth and stomatal conductance is the main mechanism by which plants respond to water stress. Pelargonium sidoides is a medicinal plant that grows in South Africa and is used for the treatment of upper respiratory ailments. Cultivation has been considered as a viable means of reducing the pressure on natural populations of this species, but little to or no information is available in this regard. Water and nitrogen supply are two of the most important factors that affect growth and yield of plants. This study therefore aimed at investigating the physiological and morphological response, in relation to growth, of P. sidoides to soil water and nitrogen levels. To achieve this objective P. sidoides plants were grown under a rainshelter and exposed to three irrigation levels (well watered treatment, moderate water stress and severe water stress treatment) and four nitrogen levels (0, 50, 100 and 150 kg · N · ha-1). Nitrogen and water stress interaction had no significant effect on measured parameters. Water stress significantly reduced stomatal conductance, while nitrogen had no significant effect on it. The well watered treatment had a significantly higher leaf area index, plant height, leaf area and fresh root yield compared to the water stressed treatments. Nitrogen level had a significant effect on number of leaves, where 100 kg · N · ha-1 had a significantly higher number of leaves compared to other nitrogen treatments. The study provides a first report on the response of P. sidoides to water and nitrogen; and showed that the plant responds to water stress by closing of its stomata and employing other morphological strategies like reducing plant growth.The authors would like to thank the Department of Science and Technology, South Africa 329 (DST-SA) for funding the study.Agriculture and Animal Healt

Competition for water between agricultural and non-agricultural economic sectors hampers agricultural production, especially in water-scarce regions. Understanding crop responses in terms of yield and quality to irrigation is an important factor in designing appropriate irrigation management for optimal crop production and quality. Pelargonium sidoides DC., often harvested from the wild, is in high demand in the informal market and for commercial formulations. Agricultural production of high-quality materials through cultivation can help reduce pressure on its wild populations. This study aimed at determining the effects of water and nitrogen on P. sidoides yield and metabolite production. The irrigation treatments applied were 30%, 50%, and 70% of an allowable depletion level (ADL), while the nitrogen (N) levels were 0 (control), 50, 100, and 150 kg ha⁻¹. The 30% ADL resulted in a significantly higher biomass and root yield. Nitrogen at 50 and 100 kg ha⁻¹ resulted in a significantly higher biomass yield, compared to the N control. An increase in sugars and citrate cycle components was observed for the well-watered 30% ADL treatment, whereas water-stressed (50% and 70% ADL) treatments increased alanine, aspartate, and glutamate metabolism, increasing levels of asparagine, 4-aminobutyrate, and arginine. The treatments had no significant effect on the root content of esculin, scopoletin, and umckalin. Water stress induced metabolite synthesis to mitigate the stress condition, whereas under no water stress primary metabolites were synthesized. Moreover, cultivation of P. sidoides as a conservation strategy can increase yield without affecting its bioactivity, while providing sustenance for the rural communities.

Africa has the largest diversity of the genus Hypoxis, accounting for 61% of the current globally accepted taxa within the genus, including some endemic species. Using Hypoxis hemerocallidea as a case study, this review addresses the conservation concerns arising from the unsustainable, wild harvesting of a number of Hypoxis species. Hypoxis hemerocallidea is one of the wild-harvested, economically important, indigenous medicinal plants of southern Africa, with potential in natural product and drug development. There are several products made from the species, including capsules, tinctures, tonics and creams that are available in the market. The use of H. hemerocallidea as a “cure-all” medicine puts an important harvesting pressure on the species. Unsustainable harvesting causes a continuing decline of its populations and it is therefore of high priority for conservation, including a strong case to cultivate the species. Reviewing the current knowledge and gaps on cultivation of H. hemerocallidea, we suggest the creation of a platform for linking all the stakeholders in the industry.

Ginger species play an important economic role as medicinal plants, food flavourings, and dietary supplements. Products from ginger, including oil and fresh and dried rhizomes can be used to treat malaria, asthma, headaches, and act as anti-inflammatory and anti-microbial agents. The cultivation of wild plant species can alleviate the pressure from harvesting from the wild. Under cultivation, the major constraints on crop yield and quality are water availability and plant nutrition. Therefore, the impact of water stress on commercial and African ginger was assessed in the rain shelter study. Irrigation treatments were based on the maximum allowable depletion (MAD) levels of plant available water in the root zone (T1: 20–25% MAD, the control; T2: 40–45% MAD; T3: 60–65% MAD; T4: 80–85% MAD). As water stress decreased, the plant height and number of stems per plant of both plant species were positively affected. The number of open stomata was higher for well-watered and less stressed treatments in both ginger species. Higher fresh and dry rhizome yields were recorded for commercial ginger at all water treatments as compared to those from African ginger. In general, water use efficiency (WUE) of fresh and dry rhizome yield was higher for commercial ginger as compared to the indigenous African ginger, while moderately stressed treatments generally resulted in the highest WUE for both species.

Moringa (Moringa oleifera Lam.) is a fast-growing tree that can reach a height of 3 m when left to grow naturally. Cutting-back management can enhance lateral branching, water use efficiency, regrowth, and leaf biomass production. Although M. oleifera can thrive in diverse ecological environments, including areas with high temperatures and drought where most crops cannot survive, the prevailing agro-ecological conditions can influence the tree’s response to cut-back and nutritional composition. An observation trial on the re-sprouting of M. oleifera after cutting back was conducted in three agro-ecological zones, including arid, semi-arid, and dry sub-humid regions. The soil analysis from the three agro-ecological zones showed variations, with the soil collected from the arid area recording the highest clay content (24.4%), nitrogen (8.14%), and phosphorus (168.2 mg/kg). The nutritional composition of the M. oleifera leaves in response to the cutting back was assessed. The trees planted in the arid region responded well to the cutting back by producing considerable new vegetative growth in the spring (13.4 sprouts averaging 21.50 cm in length) compared to semi-arid and dry sub-humid regions. The region’s climatic conditions favoured M. oleifera re-sprouting, and the stems did not die after cutting back. During the winter, the stems die back, sprout from the root collar area during more favourable weather conditions, and take longer to reach the harvestable stage. The leaves of M. oleifera harvested from the arid and dry sub-humid regions exhibited increased total fat, magnesium, sodium, phosphorus, potassium, and zinc content when compared to the semi-arid agro-ecological zone. In contrast, the calcium content of the leaves was higher in the semi-arid region than in the other agro-ecological zones. The influence of cutting back M. oleifera trees on biomass production and quality in varying agro-ecological zones requires further investigation to ensure that smallholder farmers use appropriate crop management practices in those regions for long-term, economically viable tree production.