There is a wide recognition that the global balance for food production and environmental sustainability is tipping [1], with future food and nutritional security threatened by the unsustainable intensification and expansion of industrial agriculture [2,3,4]. Increased attention is being given to alternative ways of crop production, based on traditional smallholder farming systems such as agro-ecologyFootnote 1 that promote biodiversity, reduce reliance on external chemical inputs and sustain year-round yields [3]. The International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD) for example has called for redesigning of the Global Food System in support of small-scale agro-ecological systems [4], whilst World Bank and the International Panel of Experts on Sustainable Food Systems (IPES) has noted smallholder farming to be the main pathway to enhancing productivity, profitability, environmental sustainability and poverty reduction in Africa [5, 6].
Several scholars (e.g. [7, 8]) corroborate that smallholder farming systems in Africa have the potential to sustainably provide livelihoods, food and nutritional security to most of the continent’s population. Yet the success of smallholder agriculture is largely determined by the viability and resilience of local seed systems. Such systems are estimated to account for 60–100% of seed materials planted by smallholder farmers in Africa [9,10,11] and are envisaged to remain the dominant seed source in Africa in the foreseeable future [11, 12].
Seed is the basic unit of crop production [13], and its quality is a primary determinant of yield and nutrition [9]. Yet seed is not only a vehicle for promoting productivity, nutrition and resilience, but also an entry point for achieving multiple development goals [11]. The practices that farmers use to produce, procure, save, exchange and sell seed define what we refer to as farmer-led seed systems, sometimes described in the literature as informal, traditional [14], local [15] or farmer-led or managed [16, 17]. Although such seed systems continue to be maligned as having inferior quality, few studies support this assertion. By evaluating 60 sorghum samples collected from farmers in the Uzumba-Maramba-Pfungwe (UMP) and Chimanimani districts of Zimbabwe, this study aims to fill this research gap by investigating how different seed sources and storage practices influence seed quality (storage moisture content, germination quality and fungal incidence levels).
Sorghum is the fifth most important cereal crop in the world after rice, wheat, corn and barley and the second most important crop (after maize) in sub-Saharan Africa [18]. It is also the main cereal food for over 750 million people living in semi-arid tropical regions of Africa, Asia and Latin America [19]. Sorghum is drought tolerant and has high and stable water use efficiency, tolerating temporal waterlogging and heat, whilst endowed with high germplasm variability and nutrition [20]. The crop is recommended for special diets such as for diabetics and infants since it is rich in essential minerals. It is also used as a livestock feed, for industrial manufacture of ethanol, traditional brewing, house thatching and fencing [21]. For these reasons, we focus on sorghum seed as an entry crop to evaluate the resilienceFootnote 2 of farmer-led seed systems in smallholder farming communities of Zimbabwe.
Current levels of poverty in sub-Saharan Africa, coupled with the adverse effects of climate change and the high cost of agricultural inputs, suggest that crop farming in smallholder farming communities is likely constructed around farmer-led seed systems [12]. Such systems are often criticized because seeds in their circulation are not tested for quality [22]. In contrast, the formal seed system is not always compatible with the diverse seed requirements for smallholder farming systems [23]. Farmer-led seed systems have proved to be resilient, as the systems continue to function without support from known quality assurance institutions [11, 24].
Pests and diseases, poor harvesting, handling and storage are however major challenges to seed quality. The study thus investigated fungal infections, germination and moisture qualities as key determinants of seed quality. Fungal infections cause seed moulding, a condition caused by parasitic and/or saprophytic interactions of numerous fungal species. Moulding reduces yield and affects seed viability, kernel weight and nutritional quality in sorghum [25, 26]. Although we screened five different fungal species, Fusarium sp. are the most economically important fungi in sorghum [27], causing diseases such as damping off, seed rot, head blight, root and stalk rot and seedling blight [25].
In addition, fungal grain infections also produce mycotoxins. These secondary toxic metabolites contaminate food and feed produced from infected sorghum. Mycotoxins have a huge impact on human and animal health. They cause many adverse health effects such as the induction of cancer and mutagenicity, as well as oestrogenic, gastrointestinal and kidney disorders, with some being immunosuppressive [28].
This study, which was done in Zimbabwe, provides a classic example of a country with a plethora of social, economic and ecological perturbations. The economy of Zimbabwe collapsed in the first decade of the twenty-first century, rendering its currency obsolete and crippling agricultural production [29]. This affected seed security in the context of failing formal markets, constrained disposable household income and increased vulnerability to the effects of climate change. This backdrop of a ‘failed system’ presents a fitting environment for investigating the resilience of farmer-led seed systems in the sense of its capacity to effectively supply viable and fungal-free quality seeds. Although this context is not unique to Zimbabwe, many countries in the world can learn from this experience.
