Genetic analysis of resistance to downy mildew [Peronospora arborescens (berk) de-bary] in opium poppy (Papaver somniferum L.)

Four susceptible, two moderately resistant and two resistant opium poppy varieties to downy mildew (Peronospora arborescens) were used in a diallel analysis. The F1s along with the parents were tested under three sowing dates for downy mildew infection index. Both additive and nonadditive gene actions were involved, the latter being more important. Interaction variances due to gca X dates were also significant. UO 185 and MOP 539 were good general combiners, while the cross NBPGR 1 x UO 185 was a good specific cross combination.