The Analysis of Continuous Variation in a Diallel Cross of Nicotiana Rustica Varieties.

TATISTICAL methods for the analysis of continuous variation have been S developed using second degree statistics such as variance and covariance and successfully applied to crosses between two inbred lines. These have allowed the recognition of the more familiar phenomena associated with Mendelian genetics although they appear in the analyses in a new and less obvious form (MATHER 1949; BATEMAN and MATHER 1951; MATHER and VINES 1953). The methods can be used over the whole range of mating systems employed in plant and animal breeding, selfing, sib mating, assortative mating, and can also be qdapted to randomly mating groups. In the present paper this approach has been extended to the analysis of data from a diallel cross between a number of inbred lines. The application of this method to a diallel cross in Nicotiavu rustics and published results of similar crossing programs in maize (JINKS and HAYMAN 1953) show it to be an efficient means of obtaining a rapid, overall picture of the genetical control of a character in a number of inbred lines ; at the same time throwing considerable light on the genetical basis of heterosis in the Fl progeny of these lines.