Genetical studies of fertilization in Pelargonium × Hortorum Bailey

Summary The 6×6×4 analysis of variance of the mean percentage fertilization for six variegated cultivars of Pelargonium × Hortorum Bailey, with mutant plastids in their germ layers, and for their isogenic green clones, shows highly significant differences between plastids and between female cultivars, while differences between male cultivars and the cultivar plastid interactions are much less significant. The suggestive maternal effect is not significant. The differences between cultivars and between plastids are attributed to additive effects corresponding to additive gene action. A comparison between the mean fertilization for mid-parents and their reciprocal sets of progeny shows a significant linear regression which is equated with the narrow heritability. The net fertilization achieved for each cultivar is thought to reflect small differences in the balance between the drive of pollen tubes down the style and the strength of their inhibition by already fertilized ovules.