IBL stands for inbred line. In cannabis it means a seed line taken through many generations of closely related crosses (sib crosses, backcrosses or selfing) with selection each generation, until it breeds true: its seed reliably produces plants of the same type. An IBL is homozygous at most of the loci that define its traits.
In practice
A real IBL is slow, expensive work: typically six or more generations, large populations at each step, and strict culling for herms, weak vigour and off-types. The pay-off is a line you can rely on, and an ideal parent for making uniform F1 hybrids, because it passes the same alleles every time.
IBLs also preserve a type. Many classic lines and some landraces survive only because someone kept them going as open-pollinated or inbred seed lines rather than chasing new crosses.
Ask for proof. A line called "IBL" should come with its generation history, population sizes and herm rates from tester grows.
Don't confuse with
- Landrace: a traditional, locally adapted population, often more variable than an IBL.
- Clone-only: a single genotype kept by cuttings, not a seed line.
- Polyhybrid: a recent mix of many lines, the opposite of an IBL.
- Inbreeding depression: the risk inbreeding carries; good IBL work culls it.
Inbreeding is mating between related plants, which raises homozygosity; an inbred line is the resulting population, measured by the inbreeding coefficient F.A plant is homozygous at a locus when it carries two identical alleles there (AA or aa), so it passes the same allele to every offspring.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.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 landrace is a traditional, locally adapted cannabis population kept by farmers in one region over many generations, with its own type and plenty of internal variation.Open-pollinated seed comes from a population left to cross freely among its own plants, without controlled pairs, which keeps a line's variation and type over generations.The herm threshold is GenetixBay's two-tier herm standard: a 10-plant screening grow with zero herms to be featured, then about 150 or more community-grown plants before a line can be Verified under 2% herm rate.Inbreeding depression is the loss of vigour, fertility, yield or survival that follows mating between relatives, mainly because harmful recessive alleles become homozygous.A true-breeding line produces offspring that consistently look like the parents for a given trait, because the plants are homozygous for the alleles behind it.Stabilisation is breeding a seed line over several generations, with selection each time, until it reliably reproduces the chosen traits from seed.Line breeding is a mild form of inbreeding in which plants are mated within a family, often back towards one outstanding ancestor, to concentrate its traits while limiting inbreeding.
