BACK CROSS

When F₁ individual (Tt) is crossed with one of the two parents, either tall (TT) or dwarf (tt), such a cross is called the back cross. There are two possibilities in such a cross : -

(i)         When F₁ (Tt) is crossed with the dominant homozygous (TT) parent, the plants produce will be 100% tall.

(ii)         If F₁ (Tt) is crossed with recessive homozygous (tt), 50% plants will be tall and 50% dwarf.

Uses of a Back Cross

Back crosses are used by plant breeders to rapidly improve a variety by making a useful trait (gene) homozygous, that is pure.