Heterosis

    The Historical and Biological Basis of the Concept of Heterotic Patterns in ‘Corn Belt Dent’ Maize

     W.F. Tracy and M. A. Chandler, Department of Agronomy, College of Agricultural and Life Sciences, University of Wisconsin-Madison. 

    Abstract

    In 2004 the concept of heterotic patterns is fundamental to maize breeding theory and practice, especially in temperate regions. As the use of hybrids increases in tropical maize and in other crop species, plant breeders apply the lessons of Corn Belt Dent (CBD) heterotic patterns. However, the origin and development of the concept of CBD heterotic patterns have not been critically examined. CBD heterotic patterns were created by breeders, and are not the result of historical or geographical contingencies. While the phenomenon of hybrid vigor (heterosis) and its effects on various traits have been known since the early 1900s, the concept of heterotic patterns developed in the 1960s and 1970s. Academic interest in heterotic patterns increased in the late 1980s, stimulated by the availability of DNA based markers and attempts at using markers to identify heterotic patterns. For CBD open-pollinated varieties and first cycle inbreds it would not have been possible to identify heterotic groups using molecular markers, had markers been available. CBD heterotic patterns were created by breeders through trial and error from a single race of corn. The application of the current concept of heterotic patterns in a hybrid breeding program results in increased divergence between the groups.

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