RTB: From Learning to Scaling

Led by Dr. Graham Thiele

The CGIAR Research Program on Roots, Tubers and Bananas (RTB) successfully concluded Phase I in 2016 and has now commenced the second phase of the program following the approval of a compelling and highly-rated Phase II proposal, with an enhanced focus on scaling. As both the lead center for and part of the broader RTB alliance with diverse and complementary partners, CIP has played a central role in the program’s success while also benefitting from the shared learning and perspective across RTB’s crops and partners. Root, tuber and banana crops, including potato and sweetpotato, are some of the most important staple crops in the world’s poorest regions. They provide around 15% or more of the daily per capita calorie intake for the 763 million people living in the least developed countries. Often rich in key nutrients, such as with orange-fleshed sweetpotato, RTB crops can significantly improve nutrition and food security. However, these crops also share several common challenges, including that as they are propagated clonally rather than with true seeds this allows yield-reducing pathogens to build up over time, while the crops’ bulk and perishability put pressure on postharvest innovation. Considerable progress was made in Phase I in tackling these and other challenges.

Managing seed degeneration

A cross-center initiative to improve the understanding and management of seed degeneration – reductions in yield and quality due to the accumulation of pathogens in planting material over successive planting cycles – has shed new light on degeneration’s dynamics and its management.

A common protocol was designed to estimate degeneration rates under different conditions, with the purpose of understanding quantitatively the effect of degeneration on yield and creating models that will help to predict the effectiveness of management practices. Data suggested strong and complex interactions among host, pathogen, weather conditions and seed management on degeneration rates. For example, research in Africa showed that farmers maintain sweetpotato viruses in local landraces at manageable levels using roguing (eliminating diseased plants) and positive selection (choosing healthy seed for the next planting cycle). However, some viruses are asymptomatic and may cause more yield loss in the long run than viruses with visible symptoms because farmers can’t identify infected plants for removal. Potato scientists in Ecuador demonstrated that reversion (natural reduction of pathogen incidence within a seed lot) takes place at higher altitudes, confirming the validity of a traditional practice of moving seed to high altitudes to ‘clean’ it. Taken as a whole, the results strongly suggest that host resistance in combination with on-farm management techniques and strategic use of clean planting material can lead to a cost-efficient integrated seed health strategy, especially appropriate for low-income systems.

Reducing post-harvest losses in Uganda

2016 also saw the conclusion of the three-year ‘Expanding utilization of roots, tubers and bananas and reducing their postharvest losses’ (RTB-ENDURE) project, which addressed postharvest management of potato, sweetpotato, cassava and banana. The Participatory Market Chain Approach (PMCA) developed by CIP was adapted including a gender lens and guided the design of the interventions. Through carefully facilitated processes, the project’s multi-agency research teams tested and validated postharvest innovations with the greatest potential to satisfy food consumption and income generation needs, including increasing the shelf-life of the crops and improving storage and processing technologies. In order to manage the high perishability of these crops, the project used an innovative approach that encompassed the whole value chain, from the production to the consumption end. Instead of focusing on a single technology it worked through a combination of innovations in: crop varieties, harvesting, market chain organization, and postharvest and processing technologies.

Looking forward

As Phase II gets under way, RTB scientists will pay particular attention to scaling the most promising technologies giving consideration to gender based barriers. Some technologies such as OFSP are already off to a flying start. New alliances including with Wageningen University & Research bring new insights into the scaling process. This will add value for CIP and for the RTB alliance as a whole so that we can have more OFSP-type success stories. Prospects are looking brighter for ensuring that great research will make even more of a difference to the livelihoods of those who depend upon RTB crops.