ASSESSING PROGENIES OF POTATO FOR RESISTANCE TO SKIN SPOT (POLYSCYTALUM PUSTULANS) IN THE GLASSHOUSE

Crosses were made between six parents differing in susceptibility to s kin spot and glasshouse-grown tubers from true seedlings of the nine r esulting progenies assessed for resistance to the disease. The assessm ent was evaluated by a two-year comparison with the behaviour of field -grown tubers of the progenies and their parents. The correlations bet ween progenies in the glasshouse and field were r=0.911 and 0.753 and those between the mid-parental values and the progeny means were high (r>0.864), indicating that parental differences were heritable. It is concluded that correlations were sufficient for glasshouse-grown tuber s to be used for assessing large numbers of progenies in genetical stu dies and for eliminating highly susceptible progenies at an early stag e in a breeding programme.