Research neglect of root system architecture in root and tuber crops important for Sub-Saharan African Food Security

Root and tuber crops (RTCs) provide 354 kcal/capita/day across sub-Saharan Africa (17.7% of dietary energy from major crop categories), and several countries derive over 40% of crop calories from cassava, yam, sweet potato, taro, and cocoyam. Despite this, research on the root systems that give rise to their harvested storage organs remains limited and concentrated in regions where RTCs contribute little to food security.

We combined food supply data for 46 sub-Saharan African countries (2018-2022) with a systematic bibliometric analysis of 893 RTC publications (1939-2025; 148 specifically on root system architecture, RSA), a Root Crop Dependency Index (RCDI), and scenario-based economic models, testing whether research attention is inversely related to food-security importance and whether targeted investment could yield measurable returns.

Observed results: Sub-Saharan Africa accounts for only 9.5% of global research output on root system development, despite hosting 60% of cassava production and most yam cultivation; research is concentrated in Asia (44% of publications) and North America (16%), inverting the production geography. Research effort prioritises potato (22% of publications, 13% of regional RTC calories), while yams provide 23% of calories but receive only 4% of research attention, and taro and cocoyam receive under 6%; cassava dominates regional diets (175 kcal capita-1 day-1) but accounts for only 30% of global publications. The most RTC-dependent countries (the Democratic Republic of the Congo, the Republic of the Congo, and Burundi) contribute minimal research output. Modelled projections: Scenario models suggest yield improvements of 12-25% and economic returns of 5:1-10:1, with the highest for the most neglected crops (taro, cocoyam, yam). These are modelled projections under stated assumptions, not empirical yield trials, and require field validation.

Research capacity for crops that sustain African food security is concentrated in regions where these crops contribute minimally to nutrition. This misalignment may reflect institutional path dependence, donor preferences, and the concentration of infrastructure in high-income countries rather than a systematic assessment of food-security priorities. Given their importance to food security, productivity potential, and current neglect, RTCs appear to be promising, underexplored targets for agricultural research investment; confirming the projected returns will require field trials, breeding pipelines, and adoption studies.