Breeding research in sweet potato,Ipomoea batatas Poir

As the sweet potato, Ipomoea batatasPoir, is propagated vegetatively its selection is comparatively simple. Choice of parents and selection procedures were carried out on the basis of yield capacity, resistance or tolerance to a fungus and virus disease, resistance to Cylas formicarius F. and the shape and size of tubers. Because insufficient data were available the protein content played no important role in the choice of parents. In the selection procedures, also this character could not yet be taken into account because the laboratory equipment was insufficient. This might have changed in the future.In the selection fields the new clones were planted by the side of a well-known test-clone, in such a way, that every new clone had a test on either side. At every selection cycle 25% of the new clones was kept for further research while the rest was rejected. On two generations the visible disease symptoms of new clones increased considerably while their production capacity decreased. For various characters a clear relation could be demonstrated between the phenotype of the parents and their offspring.