Heterozygosity Reduction

Heterozygosity reduction refers to the selective breeding practice of decreasing genetic diversity within a cannabis line by favoring homozygous (genetically uniform) individuals across successive generations. Breeders employ this technique to stabilize phenotypic traits—particularly morphology, flowering time, and terpene profiles—making cultivars more predictable and reproducible. Inbreeding coefficients and marker-assisted selection are common tools used to track and accelerate homozygosity in controlled breeding programs. This approach contrasts with hybrid vigor strategies and is essential for establishing true-breeding or IBL (inbred line) varieties. High homozygosity can reduce genetic load in some contexts but may increase expression of recessive deleterious alleles if selection pressure is insufficient.

Breeders reducing heterozygosity aim to 'fix' desirable traits and create stable parental lines for consistent F1 hybrids or clone-worthy cultivars. This foundational step is critical in formal breeding programs seeking to register and protect intellectual property through phenotypic uniformity.