Yield, Combining Ability and Intervarietal Heterosis in Tomato Lines.

The derivation of tomato hybrids requires an adequate selection of progenitors to generate high productivity and quality based on both the intervarietal heterosis (dominant effects) and the combining ability (additive effects). An advantage of this self-pollinated crop, is the possibility to obtain high performing homozygous lines, which can make it unnecessary the derivation of hybrids. This research was made in greenhouse under hydroponics conditions. Twenty parents and their 190 experimental hybrids were evaluated according to the diallel design II of Griffing (1956), and the Best Linear Unbasied Predictors of the genetic effects were determined. Lines were found that showed equal or higher fruit yield (of the first four clusters) relative to what was observed from the commercial hybrids. Significant effects (P ≤ 0.05) for general and specific combining ability for yield, firmness, size and fruit number were observed as well. Seventeen experimental hybrids showed higher (P ≤ 0.05) commercial fruit yield per plant relative to what was observed from the three best parents and the Cid commercial hybrid; it was due to the significant effect of heterosis with respect to the best parent. When parents were contrasting in growth habit and fruit shape the effect of heterosis was higher.