Designation (also heterosis = inequality, heteros = the other) for the pronounced performance of hybrids (hybrids) in plant and animal breeding. If the observed performance of the first filial generation (F1 = direct offspring of the parental generation) is higher than the average performance of this trait in the parental generation (parent generation), this is called a (positive) heterosis effect. Through genetically as different as possible pure-bred breeding lines of the parental generation, it is achieved in a crossing that many alleles (characteristic variants) are different.
Strongly heterozygous (heterozygous) organisms have more different genetic make-up than pure-bred animals. They are often more resistant to diseases and can adapt better to changing environmental conditions. The vine is also heterozygous, so crossing between different varieties is usually advantageous. On the other hand, negative inbreeding effects occur in the case of self-insemination (self-pollination). In this context, it should be noted that strictly speaking, crosses between varieties of the same species (such as Vitis vinifera) should also be considered as hybrids. In common parlance, these are not considered or designated as such. See also under heterozygosity and flowering.