F2 is the generation produced by crossing F1 plants with each other (or selfing an F1). Each F1 parent passes one of its two alleles at random, so the F2 contains every combination of the original parents' alleles in Mendelian ratios: 1:2:1 genotypes at each locus, 3:1 visible ratio for a dominant trait.
In practice
The F2 is the breeder's hunting ground. Recessive traits hidden in the F1 reappear, and new combinations show up that neither grandparent had. That is why autoflowering, specific colours or rare aromas from one grandparent are often recovered in an F2 rather than an F1.
The trade-off is variation. An F2 pack can range from tall to short, fast to slow, and fuel to fruit. Expect to grow more plants: for a wanted combination of two recessive traits, about 1 in 16; for three, about 1 in 64.
Don't confuse with
- F1: the uniform (or less variable) first cross.
- F3 and later: produced by crossing selected F2s; segregation narrows as selection continues.
- S1: selfed seed from one plant; similar segregation to an F2 of that plant's genotype, but every seed is female and inbreeding is higher.
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.An allele is one version of a gene; a diploid cannabis plant carries two alleles at each locus, one from each parent, which may be the same or different.Mendelian inheritance is the pattern in which single genes pass from parents to offspring in predictable ratios, following Mendel's laws of segregation and independent assortment.A recessive allele only shows its effect when a plant carries two copies of it; in a single copy it is masked by a dominant allele and carried silently.A day-neutral cannabis plant that starts flowering by age, usually a few weeks after germination, regardless of light schedule; the trait is mainly recessive.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.Segregation is the separation of a plant's two alleles at each locus into different gametes, so offspring of a heterozygous parent vary in which allele they get.Inbreeding is mating between related plants, which raises homozygosity; an inbred line is the resulting population, measured by the inbreeding coefficient F.A pheno hunt is growing many seeds of one line side by side and evaluating them to select the best individual plants, which are then kept as clones.
