A climate-resilient, root-based sweetpotato planting material (SPM) conservation method called “Triple S” or “Storage in Sand and Sprouting” has created timely access to sweetpotato planting material in areas with a prolonged dry season in Uganda and Tanzania. The aim of this study was to validate and optimize the Triple S method for conservation of sweetpotato planting material in dry areas of southern Ethiopia. The Triple S method was validated in four districts of southern Ethiopia on varieties Kulfo and Awassa 83 and compared with two common local planting material conservation methods: leaving “volunteer roots” in the soil which then sprout at the onset of rains; and planting vines under shade or mulch. Across study locations and for both varieties, Triple S resulted in a higher survival rate (81–95%) in storage during the dry season compared to the local conservation methods (7–57%). Plants of both varieties grown from roots conserved with the Triple S method showed significantly higher vine growth and lower weevil and virus infection symptoms compared to plants grown from the two local conservation methods. An additional experiment found that planting at the start of the main rainy season in June and harvesting just before the start of the dry season in October gives the highest number of medium-sized and weevil-free roots suitable for Triple S. The current study demonstrated that the Triple S method is a promising technology for small-scale sweetpotato farmers in dry areas for timely access to high-quality planting material

Finding out how to scale innovations successfully is high on the agendas of researchers, practitioners and policy makers involved in agricultural development. New approaches and methodologies seek to better address related complexities, but none of them include a systematic perspective on the role of capacity in (partnerships for) scaling innovations. We posit that this has left an important topic insufficiently addressed in relation to partnerships for scaling innovations. The need to address this gap became apparent in the context of the CGIAR Roots, Tubers, and Bananas (RTB) Scaling Fund initiative. This paper presents how we explored ways forward in relation to this by combining three methodological approaches: The Five-Capabilities, Scaling Readiness, and the Multi-Level Perspective on socio-technical innovation. This combined approach—dubbed Capacity for Scaling Innovations (C4SI)—was applied in three projects related to scaling innovations for sweet potato, cassava and banana, involving five countries in Africa. It then discusses implications for a partners-in-scaling perspective, the contribution of scaling innovations to sustainable development, the importance of research organisations considering their own capabilities in partnerships for scaling, and the extent to which C4SI was helpful in the three cases—for example, in decision making. The paper concludes that a capacity perspective on the scaling of innovations should be an essential part of a ‘science of scaling’. Finally, it provides recommendations for using the approach or parts of it in research and intervention practice for scaling, pointing in particular to the need for context-specific adaptation.

True-to-type clonal fidelity is one of the most important prerequisites in micropropagation of crop species. The aim of this study was to assess the effect of long-term in vitro subculturing on the variety degeneration of three sweetpotato varieties (Monate, Mokone and Ndou). Monate was subcultured for 32 generations, whereas Mokone and Ndou were subcultured for 23 and 12 generations, respectively. The media used for subculturing contained 4.43 g/l of MS (Murashige and Skoog) salt, 30 g/l of sucrose and 2 g/l of gelrite. The plantlets were grown in a 16 h light and 8 h dark photoperiod for 30 days, and single node cuttings taken from the 30-day-old plantlets were used as the explant source to subculture the next generation. From each generation, 45 plantlets were transplanted and grown for 2 months in a glasshouse. Data on in vitro growth performance, as well as morphology during acclimatization were recorded. The plantlets which showed a change in morphological traits were subjected to genetic analysis by using five simple sequence repeat (SSR) primers (IB-242, IB-318, IB-255F, IB-248 and IB-255). Significantly higher growth performance, such as stem height, leaf number, internode length, as well as early root and shoot organogenesis, was observed after the 27th and 21st subcultured generations of Monate and Mokone, respectively. Furthermore, plantlets of the same variety showed differences in morphological traits such as leaf colour, abaxial leaf pigmentation, vine pigmentation, petiole pigmentation, leaf wrinkling and percentage of flowering. However, there was no correlation between the subcultured generation and the degree of morphological variability. From the five SSR loci, only IB-255F and IB-318 were able to distinguish between the three varieties. However, no allelic polymorphisms were detected between short-term and long-term propagated plantlets with the primers used in this experiment. Therefore, long-term nodal subculturing did not lead to quality degeneration of sweetpotato varieties Monate, Mokone and Ndou.

Triple S (Storage in Sand and Sprouting) is a root-based system for conserving and multiplying sweetpotato planting material at the household level. In sub-Saharan Africa, farmers predominantly source planting material by cutting vines from volunteer plants that sprout from roots left in the field from a previous crop. However, it takes 6 to 8 weeks after the rains start to produce enough vines for planting material, and normally these vines are infected by sweetpotato diseases and pests carried over from previous crops. Where rainfall is unpredictable, farmers can use Triple S to take advantage of the whole growing season, planting and harvesting early to obtain food, higher yields, and income. Triple S facilitates household retention and adoption of new sweetpotato varieties, notably the beta-carotene-rich, orange-fleshed varieties. Triple S PLUS is the combined innovation package of core Triple S components and complementary components used to scale the innovation. These included good agricultural practices, different storage containers, local multiplication and sales of planting material, and a multimedia communication strategy for training and extension to encourage the uptake of Triple S. Components were at different levels of scaling readiness. This chapter explores evidence from Ethiopia and Ghana (2018–2019) on the extent to which exposure to different communication channels and their combinations influenced the uptake of Triple S PLUS by male and female farmers, the partnering arrangements that supported this, and the resulting changes in food security. We discuss implications for future scaling initiatives.