Roots, tubers and bananas (RTB crops) are the foundation of food security for millions of people across Asia, Africa and Latin America. They will be increasingly important in response to climate change, population growth and urbanization; and they can contribute essential micronutrients such as iron, zinc and vitamin A that are especially important for good health in children and mothers. A research brief from the CGIAR Research Program on Roots, Tubers and Bananas (RTB) makes a strong case for the fundamental importance of its mandate crops within One CGIAR, the ongoing reformulation of CGIAR’s partnerships, knowledge, assets and global presence. With further research and development, enhanced yields of RTB crops will help to address the United Nations' Sustainable Development Goal (SDG) 1 of ending poverty. To date, however, research investment in RTB crops has lagged.

The production of root, tuber and banana crops in developing countries has surged in recent years. A review published in the International Journal of Food Science & Technology suggests that the surge will continue to 2030, considering past trends and recent projections. More than three billion people in developing countries consume RTB crops. For many of the developing world’s poorest farmers and food-insecure people, RTB crops are a critical source of food, nutrition, animal feed and cash income. That production leads to an estimated annual farm-gate value of $339 billion.

We often get asked why bananas are lumped together with roots and tubers. Partly, this has to do with the way they are grown; but it also has to do with their key role as staples — that are more perishable than cereals — in many developing countries. These crops are all vegetatively propagated from bulky and perishable planting material. This creates common challenges for seed production and distribution, as well as severe challenges from disease accumulation, and its subsequent spread. In addition, seed systems are mostly informal, with farmers sharing planting material from their fields. 

Across the humid tropics of Africa, RTB crops are the principal staples, supplying 25%-57% of calories in the diet. As they are bulky, perishable and often eaten fresh, they pose common challenges for post-harvest systems as well as opportunities for adding value. Despite this dependence, the low productivity of RTB crops in sub-Saharan Africa reduces their contribution to addressing undernutrition in rural populations. At the same time, inefficient traditional post-harvest management and supply chain logistics for RTB value chains mean that countries import large quantities of staple grains for rapidly growing urban populations.

Outside the humid tropics of Africa and in most of Asia and Latin America, RTB crops are important in rotation with cereals and legumes and agroforestry systems. Roots, tubers and bananas enhance resilience because they often have key traits that enable them to survive shifting weather patterns, including droughts and flooding, adverse soil conditions like salinity and waterlogging, as well as catastrophic events such as tropical storms (because roots and tubers are buried safely underground).

Benefits for sustainable development

Research will be needed to ensure RTB crops play an even greater role in response to population growth, urbanization and climate change, and to contribute to the SDGs. For example, climate change means that maize may be vulnerable to more frequent droughts, while cassava and sweet potato are more resilient under such conditions.

Where market conditions are right and new technologies are available, as in Southeast Asia for cassava, yield increases have been considerable. Hence, attention needs to be given to creating the right incentives for innovation and yield increases elsewhere. For example, some public-sector investment for early generation seeds can complement the private sector to create an enabling environment for investment in seed systems, often a critical bottleneck in varietal adoption. In addition, public-private partnerships are reducing cassava waste by processing cassava peels into feed for livestock and fish, both eliminating waste and creating opportunities for new employment. Women, especially, stand to benefit from growing and using RTB crops. At present, yields on female-led farms are often lower because of gender-specific barriers. Research is needed to improve yields for female farmers and to enhance their role in the production of value-added foods for urban consumers. On a longer timescale, the CGIAR Gender and Breeding Initiative is working on a range of gender-responsive breeding tools to ensure that women’s needs and preferences are also addressed in breeding programs, to improve productivity and accelerate adoption while creating equitable benefits for both genders.

RTB crops are also important to meet SDG 2: zero hunger. Because they are produced, processed and traded locally, they are less susceptible to price shocks in international markets and disruptions in global trade. This can be considered another aspect of their resilience which became more acutely apparent during the COVID-19 pandemic disruption of markets and value chains.

Looking forward

While considerable strides have been made in demonstrating the power of RTB crops to fight hunger and nutritional insecurity, huge challenges remain. The widespread low productivity of RTB crops, their bulk and perishability and their relative neglect by decision-makers are all preventing them from playing a bigger role.

The production of RTB crops will have to almost double by 2050 to keep up with growing populations and increasing demand. Therefore, increased investment in RTB crops will help to fill the gaps, delivering more food from the same amount of land, with less waste and lower greenhouse gas emissions.