Yielding Ability and Competitive Influence in Hybrid Mixtures of Maize1

Abstract

Ten short‐season commercial maize (Zea mays L.) hybrids were grown in pure stands and all possible equal‐proportion mixtures over a two‐year period at Guelph, Ontario. Differential stress was imposed by varying plant densities. Data were recorded for grain yields, ear moisture percentage and lodging percentage. Individual component data were collected in the second year.No significant differences in grain yield were observed in either year among plant densities. Further, no differences were noted between observed yields of the mixtures and midcomponent means. This contrasts with many studies in self‐pollinated species.Analysis of individual component data showed that the yield contribution of the components was disproportionate: hybrids that yielded highest in pure stands contributed more to a mixture than would be expected based on their pure stand yield and the lower yielding hybrids less than expected. These results suggest that natural selection in gene pools of cross‐fertilizing species would result in higher‐yielding genotypes. Ears of early maturing hybrids tended to dry more slowly when in mixtures and later hybrids more rapidly, relative to their drying rates in pure stands. Standability of mixtures was unrelated to respective standabilities of the various components in pure stands.