Principles of Genetics and Breeding (1+1)

2.1.8 F1 Generation

F₁ is the symbol given to the first filial generation of progeny from a cross of non-siblings. This cross is represented by (P₁ x P₂ = F₁). When representing a cross, you use parent (P) to indicate the original breeders. You can only get to an F₂ by breeding siblings (F₁ x F₁ = F₂). If you cross back to a grandparent, the resulting fry are also F₁’s, because it would be represented the same way as the first example (P₁ x P₂ = F₁).