Roots, Tubers and Bananas: Planning and research for climate resilience

The CGIAR Research Program (CRP) on Roots, Tubers and Bananas (RTB) includes vegetatively propagated staple crops linked by common breeding, seed, and postharvest issues, and by the frequency with which women are involved in their production and use. RTB crops are the backbone of food security across the humid tropics in sub-Saharan Africa (SSA) and in more localized areas of Asia and Latin America. Around 300 million poor people in developing countries currently depend on RTB value chains for food security, nutrition and income. Climate change poses challenges which could undo progress in poverty reduction and markedly increase food insecurity. This article examines planning and research for climate resilience across RTB crops, with a particular focus on the contrasting potato and sweet potato cases in SSA. A six-step framework for climatesmart breeding is proposed: (1) downscaling climate change models and crop modeling; (2) identifying and understanding key climate change responsive traits; (3) Review Article Open Access Graham Thiele*, Awais Khan, Bettina Heider, Jürgen Kroschel, Dieudonné Harahagazwe, Maria Andrade, Merideth Bonierbale, Michael Friedmann, Dorcus Gemenet, Mihiretu Cherinet, Roberto Quiroz, Emile Faye, Olivier Dangles Roots, Tubers and Bananas: Planning and research for climate resilience *Corresponding author: Graham Thiele, CRP on Roots, Tubers and Bananas (RTB), led by International Potato Center, Lima, Peru, E-mail: [email protected] Michael Friedmann, CRP on Roots, Tubers and Bananas (RTB), led by International Potato Center, Lima, Peru, Awais Khan, Bettina Heider, Jürgen Kroschel, Merideth Bonierbale, Dorcus Gemenet, Roberto Quiroz, International Potato Center (CIP), Lima, Peru Dieudonné Harahagazwe, International Potato Center (CIP), Nairobi, Kenya Maria Andrade, International Potato Center (CIP), Maputo, Mozambique Mihiretu Cherinet, International Potato Center (CIP), Addis Ababa, Ethiopia Emile Faye, Centre de Coopération Internationale en Recherche Agronomique pour le Développement, (CIRAD) Olivier Dangles, Institut de la Recherche pour le Development (IRD) © 2017 Graham Thiele, et al., published by De Gruyter Open. This work is licensed under the Creative Commons Attribution 3.0 Public License. Unauthenticated Download Date | 4/3/18 7:25 AM Roots, Tubers and Bananas: Planning and research for climate resilience 351 2 Climate change and poverty impacts Through the humid African tropics RTB crops are the most important staple and the dominant commodity in the system. The contribution of foods derived from RTB crops to total caloric needs ranges from nearly 25% in Nigeria to close to 60% in the Democratic Republic of Congo (RTB 2016). There are marked cultural preferences for RTB crops in these SSA countries. Using the Impact General Equilibrium Model, a 2015 analysis in by the International Food Policy Research Institute shows that per capita consumption will continue to rise (Figure 1). Because of low productivity, current RTB production in SSA does not meet basic needs in rural areas. Moreover, low productivity often weakens the crops’ competitiveness with imported staples for urban consumers, resulting in missed smallholder income currently depend on RTB value chains for food security, nutrition, and income; many more benefit through their consumption. RTB crops are increasingly taking on roles in income generation. However, climate change could potentially undo progress in poverty reduction and markedly increase food insecurity, especially in SSA where RTB crops are very important. This article examines planning and research for RTB crop climate resilience with a particular focus on potato and sweet potato in Africa. These contrast in the agroecological niches they occupy and their roles in livelihoods. Potato is found at higher, more temperate elevations and is a more input-intensive cash crop. Sweet potato grows at lower, more tropical elevations and is a more robust crop for food security. Both are expanding very rapidly in Africa and are likely to be impacted differently by climate change. This article proposes a general framework for climate-smart breeding to address these challenges. WLD = World; EAP = East Asia and Pacific; EUR = Europe; FSU = Former Soviet Union; LAC = Latin America and Caribbean; MEN = Middle East and North Africa; NAM = North America; SAS = South Asia; SSA = sub-Saharan Africa. Bananas are included under fruits and vegetables. Figure 1: Forecast sustained per capita demand for roots and tubers to 2050 (source: K. Wiebe 2015) Unauthenticated Download Date | 4/3/18 7:25 AM 352 G. Thiele, et al. 2.1.1 Step 1. Looking into the future Downscale climate change models and crop modeling to (a) define target environment sets by crop, and (b) understand yield impacts and drivers of yield loss by crop (including pests). Climate change impacts crop yields in complex ways as depicted in Figure 3. Increasing carbon dioxide (CO2) concentrations can have a fertilization effect and some locations will show higher rainfall, but increased heat or drought can adversely impact yield. Jarvis et al. (2012) used different global climate change models linked with the Ecomodel of crop suitability and parameters of major staples in SSA. Potato was one of the crops that showed the greatest negative effects crop suitability declined (−14.7% ± 8.2) by 2030, along with beans (−16% ± 8.8), probably because they occupy similar highland climatic niches. Cassava was positively impacted by climate change in many areas of Africa, with −3.7% to +17.5% changes in climate suitability across the continent. The results, however, are difficult to relate directly to yields, as they would be sensitive to the parameter values selected, such as maximum temperatures tolerated. Furthermore, sweet potato was not included in the exercise. As the authors also recognize, indirect effects of climate change on cassava through buildup of pests opportunities. As more people move to cities, value chains for RTB crops will need to be reconfigured to improve efficiency and convenience and reduce postharvest losses to compete. Climate change will impact agri-food systems and worsen poverty in different ways. One of the most important effects is through reducing productivity and raising food prices (Figure 2). This is of concern worldwide, but without significant technology to cope with climate change this is likely to be of special importance in SSA. This is precisely where RTB crops are of the highest relative importance, with further expansion in the pipeline as the population of these countries continues to grow. Technological change in roots and tubers is essential to damp food price increases and risk of hunger under any climate change scenario. This article focuses on climate-smart breeding as a key element in the RTB response. 2.1 Steps in climate-smart breeding RTB has identified six steps in climate-smart breeding. These are not sequential as some steps feed back to earlier ones. They are: 1 Figure 2: Effect of climate change on agricultural prices under different scenarios (source: Hallegatte et al. 2016) Poverty and high emissions w/o CO2 fertilization Poverty and high emissions Poverty and low emissions Prosperity and high emissions w/o CO2 fertilization Prosperity and high emissions Prosperity and low emissions a. World