An Expansion of Jones's Theory for the Explanation of Heterosis

Abstract

Because of certain statistically substantiated results following hybridization of inbred tomato lines, an expansion of Jones'' theory for explaining heterosis became necessary. In certain crosses, the number of fruits and wt. of individual fruits both showed no heterosis, but were intermediate between the parents. The total yield in wt. of fruits was nonetheless greater than for either parent. This multiplicative effect of gene action makes it necessary to modify Jones'' postulate that the genes responsible for heterosis are dominant or semi-dominant. The author suggests the use of "non-beneficial heterosis" when heterosis for an undesirable character is exhibited.