Polygenic Trait Fixing

Polygenic trait fixing refers to the selective breeding process of stabilizing characteristics controlled by multiple genes rather than a single locus. In cannabis breeding, traits like plant height, yield potential, cannabinoid ratios, and terpene profiles are commonly polygenic—inherited from both parent plants across numerous genetic locations. Breeders working in this category employ multi-generational selection to increase the frequency of desired alleles and reduce phenotypic variation within a line. This approach requires patience and careful record-keeping, as progress is typically incremental compared to monogenic trait selection. Understanding polygenic inheritance helps explain why stabilizing a new cultivar often takes 6–10+ generations of controlled crossing and backcrossing.

Breeders use polygenic trait fixing to develop stable, true-breeding cultivars with consistent expression of complex characteristics. Marker-assisted selection and test-cross data now help accelerate this process by identifying individuals carrying favorable allele combinations before flowering.