Inheritance of resistance to Fusarium sulphureum in crosses between S-tuberosum potato cultivars measured on field and glasshouse grown tubers

Solanum tuberosum potato cultivars with differing levels of resistance to d ry rot caused by Fusarium sulphureum were hybridised in a half diallel cros sing programme. Glasshouse grown tubers from true seedlings and field-grown tubers of the resulting progenies were assessed for their resistance to F sulphureum. Statistical analysis revealed differences between the progenies for F. sulphureum resistance on both field and glasshouse grown tubers. On the field grown tubers, differences between progenies were due to differen ces in the general combining ability (GCA) of the parents. Parental phenoty pes and GCA values were highly correlated. Overall, GCA was consistent for resistance or susceptibility, and glasshouse gown progenies showed a good c orrelation for GCA between years (r=0.85***), and with the results of the f ield grown progenies (r=0.61* in 1998 and r=0.69** in 1999). It appears tha t resistance to F. sulphureum is heritable, and that this heritability is b etter assessed on field grown rather than glasshouse grown tubers, although the two are largely in agreement.