Sweetpotato seed systems in Uganda, Tanzania, and Rwanda

Surveys were made of the seed systems used in Uganda, Tanzania, and Rwanda and to investigate the reasons underlying them. Along the equator in Uganda, where rainy seasons are evenly spaced and occur twice a year, vine cuttings from mature plants only are used as planting material. Where there is a long dry season, the seed system includes a diversity of means of conservation: the passive production of volunteer plants from groundkeeper roots sprouting when the rains come; small-scale propagation of plants in the shade or backyard production using waste domestic water; and relatively large-scale propagation in wetlands or irrigated land. The last is the only means of obtaining sufficient quantity for sales, but is also the most expensive. Volunteers only produce planting material one or two months after the start of the rains and tend to be regarded as common property; nevertheless, they are an important source of planting material for poorer farmers. Although farmers perceive multiple benefits from planting early, planting material is in short supply at the beginning of the rains and mainly larger scale farmers gain these benefits. Farmers select carefully to avoid using plants with symptoms of virus disease as planting material and may also remove any diseased plants from crops