A glasshouse progeny test for resistance to tuber blight (Phytophthora infestans)

The susceptibility to tuber blight (Phytophthora infestans) of seedling progenies from ten crosses involving resistant and susceptible parents was assessed by inoculating tubers grown in the glasshouse and in the field. The mean level of tuber blight in each progeny corresponded with the resistance category of the cross, and the rank order of increasing susceptibility was almost identical in both tests. It is suggested that two samples of ten glasshouse-grown seedlings, each seedling providing two tubers harvested as the plants begin flowering, is an adequate sample size on which to predict the tuber blight susceptibility of a progeny.