P1 (the parental generation) is the pair of plants crossed to start a breeding programme. Their seed is the F1, the F1 crossed among itself gives the F2, and so on. In some texts the parents are written simply as P.
In practice
In cannabis the P1 pair is usually one selected female (often a clone) and one selected male. Documenting them properly is the foundation of any honest lineage: name or GB-style ID of each parent, where they came from, photos, test results and the date of the cross. Without that, every later generation inherits a guess.
The P1 parents do not have to be inbred. When they are heterozygous hybrids themselves, as most modern cannabis is, the "F1" is already variable. Breeders then talk about F1s loosely, but genetically that seed behaves more like an F2.
Don't confuse with
- F1: the offspring of P1, not the parents.
- Recurrent parent: in a backcross programme, the P1 plant crossed back into again and again.
- Mother plant: a horticultural term for a plant kept for cuttings. A mother can be a P1, but not every P1 is kept as a mother.
F1 is the first generation of offspring from crossing two parents; if the parents are inbred and different, F1 plants are uniform and often show hybrid vigour.F2 is the second filial generation, made by crossing or selfing F1 plants; it shows the widest segregation, bringing back hidden recessives and new combinations.The daily length of light versus dark; photoperiod cannabis flowers when nights grow long enough, rather than at a fixed age.A plant is heterozygous at a locus when it carries two different alleles there (Aa), so its offspring can inherit either one and segregate.A hybrid is the offspring of two genetically different parents; almost all modern cannabis is hybrid, built from crosses between landrace-derived and other lines.A backcross is a cross of a hybrid back to one of its parents (or that parent's line), repeated to recover the parent's traits while keeping one introduced trait.A mother plant is a female kept permanently in vegetative growth to supply cuttings, so a selected genotype can be propagated as clones indefinitely.Filial generations (F1, F2, F3 and on) count generations of offspring from an original cross, each made by crossing plants of the previous generation together.
