Predicting Yield of Synthetic Varieties1

Formulae for predicting yield of synthetic varieties are useful in two ways. First, they presumably have predictive value, and second, if they have predictive value, the formulae define those factors that control yield. Such formulae give the relationship of one yield factor to another. In this paper I derive prediction formulae which will, I believe, successfully predict yield. These formulae take into account the effects of ploidy, selfing, number of parents, inbreeding of parents, combining ability of parents, relationship between parents, and the generation of multiplication of the synthetic variety. The formulae are based upon the observation that heterosis increases with outbreeding and diminishes with inbreeding. A linear relationship between yield and heterozygosity is assumed but the formulae also should be useful when the relationship between yield and heterozygosis is nonlinear, providing a satisfactory transformation of the yield data to fit the linear relationship can be found. The level of heterozygosis is expressed as the coefficient of inbreeding F.