Male gametophyte in maize: II. Pollen vigor in inbred plants.

The competitive ability of pollen from inbred plants in mixed pollinations in this study is not merely maintained but enhanced through successive generations of selfing. The data presented suggest two conclusions: 1) the possible existence of pollen-stylar interactions during successive selfings, which select for certain pollen genotypes, those best suited for rapid growth through "self" styles; and 2) the presence of sporophytic vigor in the heterotic F1 sporophyte, or its absence in the "depressed" F7 sporophyte, is not necessarily demonstrated in the gametophytic generation, perhaps because it can be overwhelmed by other factors, e.g. gametophytic response to selection.