At a recent workshop that we hosted at the first Postdoctoral Conference of Southern Africa, the social and cross-cultural beliefs that may prevent the maximum utilisation of weeds as potential food sources were under the spotlight. One of the aims of this workshop was to develop an integrated transdisciplinary strategy to promote traditional edible weeds as commercial produce to combat future food insecurity, which is fast becoming a reality in Africa. Researchers and thought leaders attending the event came up with ways to address some of the issues and assessing some of the potential implications of weeds for future food security.
As species from wild or semi-cultured plants, weeds are usually problematic in food crops, leading to reduced yields. According to the Food and Agriculture Organization (FAO), there are approximately 30 000 species of weeds that account for losses in the yield of major crops including tobacco and wheat, various vegetables, fruit, and vineyards. Because of this, billions of dollars are spent each year on weed control in agroecosystems. However, as much as weeds need controlling for the protection of major crops, there are many weeds that are edible, indigenous, and are used by local communities.
In commercial farming settings, weeds are completely ignored with regards to their positive contribution towards food security. For example, the genus Amaranthus, which includes approximately 70 species, is considered a cosmopolitan weed with associated invasion in agroecosystems after soil disturbance and seed exposure to light. While many commercial farmers, especially in South Africa, struggle to control the weed, in other African countries, Amaranth (pigweed, morogo, umfino, or African wild spinach) is a nutritious food source that is high in protein and starch (grain), as well as minerals and vitamins (leaves). Historically, weed research has focussed on the control and/or destruction of agricultural weeds, including many species of edible morogo.
The globalisation of agriculture and, consequently, its industrialisation in Africa is inevitable, especially in South Africa. This has negative implications for food security because of biased technological development of some high-in-demand plant species (e.g., wheat, rice, potato, etc.). Some of these high-in-demand species are poorly adapted for the African climate. This continued monoculture production and breeding leads to reduced genetic diversity or a loss of agrobiodiversity.
Agrobiodiversity refers to the biological diversity of agriculture-related species and their wild varieties which occurs at the agro-ecosystem, species, and genetic levels. With the threat of global climatic change, coupled with the loss of agrobiodiversity, it is expected that many cultivated crops’ yields will decrease because they have not been cultivated for their ability to withstand extreme weather conditions. Of the approximately 10 000 edible plants species, nearly 200 are commercialised and used for human consumption and approximately 75% of an individual’s caloric needs are met with 12 plant (and 5 animal) species, of which 60% is from rice, maize, wheat, and potato. The narrowing of food crops with the increase in the number of specialised crops that humans depend on has implications for food insecurity, economic growth and high risks for rural household incomes and livelihoods. In essence, urban food security is at higher risk than in rural settings.
Many rural households still rely on crops that are not major commercial crops and have managed to maintain agrobiodiversity in their diets. One of the main reasons that have led to the loss of agrobiodiversity in our diets is that with an increase in urbanisation, a socio-economic transition to different foods and diets occurs, which contributed to food (in)security. A continuum emerges that begins in rural areas and moves from semi-rural, to peri-urban and ends in urban areas.
This rural-urban migration trends lead to evolving nutritional habits and food supply strategies. In urban areas people are more likely to eat processed food that contain higher sugar levels. Moreover, in urban settings, physical food access requires more financial access, and as a result people become more vulnerable to food price hikes, leading to food insecurity and hampering socio-economic development. As such, poorer urban dwellers are at risk of consuming insufficient and low-quality food.
The important role that edible weeds can play in the battle against food insecurity is underscored by the latest FAO 2018 State of Food Security and Nutrition in the World report which points out that over 820 million people are suffering from chronic undernourishment. If we consider that 70% of the world’s poor live in rural areas, the cultivation of indigenous edible weeds deserves greater attention. These weeds are able to withstand severe weather conditions and manage to thrive in the wild without any human intervention.
They might not be the high-in-demand crops that we are used to, but weeds can play a significant role in helping to reduce hunger in many parts of the world. With the global population projected to reach 9 billion by 2050, we can no longer afford to ignore this important food source.