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Seed Systems

In areas where there is a prolonged dry season, sweetotato vines die due to lack of moisture or through being eaten by livestoc and so are not avialable to supply cuttings. When the rains come and farmers want to plant straight away, there are no planting materials available. Farmers typically then have to wait for the rains to cause vines to emerge from old roots that were left in the field, causing delays in planting. This lack of planting materials at the on-set of rains is a major constraint to sweetpotato farming in sub-Saharan Africa. 


In order to ensure access to sufficient high quality planting materials at the start of the rains, dry season preservation is necessary. Dry season conservation methods selected vary based on the socio-ecological characteristics of the household.


The Triple S (Storage of roots in Sand then Sprouting) technology is being validated in new contexts in sub-Saharan Africa. Triple S can be used for conservation and multiplication of sweetpotato planting material in areas with an extended dry season.


At the start of the rains, local availability of adequate quantities of quality planting material is limited. However, farmers using the Triple S technology can plant earlier and take full advantage of the rains to obtain higher yields. Thus, they benefit from an early food crop, before cereals can be harvested.  


Ensuring that households have control over their own seed source, by retaining healthy roots and sprouting them, reduces the need to transport perishable and bulky planting material over long distances, at high cost and often with high wastage.  We will continue to adapt the Triple S technology for local conditions and develop appropriate strategies for scaling out to reach more farmers.

Seed systems are required for all crops. If effective, they provide farmers with sufficient quantities of vigorous disease-free planting material of the required varieties at an affordable price and in time for the planting season. Seed systems can range from those managed by farmers for their own use, those where some of the seed is bartered or traded with nearby farmers, to those where the seed is produced by national organizations or private companies following strict regulations and at large scale.


There needs to be capacity within the seed system to securely maintain pure disease free seed, to generate new varieties with attractive characteristics, and to multiply and disseminate seed. In societies where sweetpotato is considered a 'woman's crop', seed management practices and knowledge are normally in the 'woman's realm'. The gender context and dynamics of existing seed practices need to be understood.


In areas with prolonged dry seasons, farmers are unable to access sweetpotato planting material from their previous field crop, and so methods of preserving planting materials during the prolonged dry season and accessing them in time for the new season have developed. Many farmers just wait for the new rains to cause the few sweetpotato storage roots which were left behind in the field at the last harvest to sprout and to then produce foliage. Other methods include the preservation of planting materials in swamps, shady areas of the household yard, and around drainage areas.


In some areas, farmers purchase planting material form those with good access to water and who specialize in the supply of planting material. However, these sources may not always be accessible to the majority of smallholder farmers, in particular women farmers.  It is therefore, important to have a reliable decentralized system where multipliers can maintain clean planting material for easy access by farmers.


Most projects and organizations tend to organize their own seed systems to supply clean planting materials to their target communities. However, under the umbrella of the  SPHI, there are initiatives to test different technologies, farmer practices and internal and external quality assurance mechanisms for maintaining healthy seed production; and to help build appropriate and cost-effective external regulatory processes.


Whilst interventions to improve seed systems have frequently been achieved at pilot level, the challenge is much greater when it comes to working at the scale of impact required to bring the benefits of clean planting material and / or improved varieties to a wider geographical and higher population coverage.




Quality seed is the starting point for any successful agricultural venture and a functioning sweetpotato seed system contributes to food security and income generation. The transition between breeder and pre-basic (i.e. first generation or foundation) seed production is a major bottleneck in the functioning of an efficient seed system for sweetpotato. This is because of: limited incentives to maintain breeder seed; a lag in investment in human capacity and facilities for pre-basic seed production; inadequate coordination between seed demand and supply; together with unreliable funding streams.


There are initiatives to develop and test different seed system technologies and innovative partnership business models to increase the multiplication rate for sweetpotato and improve the consistent supply of quality, early generation seed.



These initiatives aim to strengthen technical, financial and institutional capacities for the sustainable production of pre-basic sweetpotato seed. They also explore innovative partnership business models between public research programmes and private entities that would contribute to the broad goal of developing commercially viable seed systems.


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