I don't know much about it but i think it is when When you crosses 2 plants of the same pure lines parentage, the resulting F1 is termed as true-breeding plants.
True-breeding plants can also be produced by selfing (or self crossing) flowers form a pure line plant. When seeds from this fertilization are planted, they will give rise to homologous-homogeneous population.
HOPE I HELPED U ^﹏^
