Sustainable seed systems for vegetatively or clonally propagated crops such as sweetpotato fulfill a number of critical roles: The timely provision of planting material of appropriate quality for smallholders, The efficient dissemination of new improved varieties from breeding programs, The provision of replacement planting material following natural disasters or in times of crisis or unrest.

The provision of improved planting material for clonal crops has a proven track record in poverty alleviation through raising crop productivity, both through improved seed quality and through the dissemination of improved varieties with their associated pro-poor traits. The provision of planting material of appropriate varieties is also often seen as a key intervention to rehabilitate farming systems following natural disasters such as drought, civil unrest or conflict, and in assisting the return of displaced persons.

An example of the potential impact of sustainable seed systems in clonal crops is given by the adoption of the International Potato Center (CIP) sweetpotato seed technology (virus testing and tissue culture) in the Shandong province of China in the period 1988 to 1998. The technology was adopted over 80% of the production area of the province, which represents 12% of global sweetpotato production, amounting to some 17 million tons per annum, and resulted in average yield increases of 30%. The economic impact of this intervention was later estimated as providing an annual productivity increase valued at $145M per annum by 1998 (Net present value [NPV] $550M; Internal rate of return [IRR]of 202%), and the agricultural income of some 7 million smallholder farmers had been raised by some 3-4%.