Open-pollinated (OP) seed is produced by letting many plants of one population cross freely among themselves, by wind or by hand pollen mixes, instead of crossing one chosen female with one chosen male. Grown in isolation from other types, an OP population keeps its character from generation to generation while holding plenty of internal variation.
In practice
Most landraces were maintained this way for centuries: a farmer saved seed from the best plants of a field each year. OP lines are resilient and adaptable because they carry many alleles. They are also the practical way to preserve a population, as opposed to a single clone.
Doing it well means a large enough population. Seed saved from two or three plants each year narrows the gene pool fast through genetic drift and inbreeding. Seed banks maintaining OP accessions aim for dozens of parents or more per regenerationbeing reviewed.
Don't confuse with
- F1 hybrid: a controlled cross between two parents, usually uniform; its seed does not stay true.
- Landrace: a type of OP population with local adaptation and history; not every OP line is a landrace.
- Uncontrolled pollination: a room with a stray herm is accidental pollination, not an OP programme.
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.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.The gene pool is the total set of alleles present in a population, cultivar group or species; a narrow gene pool limits what breeders can select from.Genetic drift is random change in allele frequencies between generations of a seed population, strongest in small populations; clones do not drift this way.Inbreeding is mating between related plants, which raises homozygosity; an inbred line is the resulting population, measured by the inbreeding coefficient F.In cannabis slang, a seed bank is a vendor that sells seed from one or many breeders; it is not the same as a conservation genebank.An accession is a distinct sample of plant material (seed, tissue or cuttings) entered into a collection or gene bank under its own ID with records of origin.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 heirloom is a seed line kept and passed down by growers for decades, usually outside its region of origin, preserving an older type rather than a recent hybrid.An IBL (inbred line) is a seed line that has been inbred and selected over many generations until it breeds true for its main traits, giving uniform offspring.
