Heterosis (hybrid vigour)

Heterosis, also known as the hybrid vigor effect, is the superiority of the F1 generation over the average of the parents or the superior parent in terms of a specific measured trait. It can apply, for example, to vigor or yield, but not every cross produces a positive and practically significant effect. The uniformity of F1 plants results primarily from the homogeneity of the parental lines, rather than from heterosis itself. In the next generation, traits undergo segregation; therefore, seeds harvested from F1 usually do not reproduce its characteristics.