Heterozygosity

Heterozygosity describes a plant's genetic condition where alleles (gene variants) at a given locus differ between the two chromosome copies inherited from each parent. In cannabis breeding, heterozygous plants carry mixed genetic instructions—for example, one allele for leaf shape from the mother and a different version from the father. This genetic diversity within individual plants is foundational to breeding programs, as heterozygous individuals often display hybrid vigor (increased vigor, yield potential, or resilience compared to either parent). Understanding heterozygosity levels helps breeders predict trait expression, stabilization timelines, and the consistency of offspring across generations.

Breeders strategically maintain or reduce heterozygosity depending on goals: F1 hybrids are deliberately heterozygous to capture vigor and hybrid effects, while stabilized IBL (inbred line) or IBL-derived strains involve repeated selfing or controlled crossing to increase homozygosity and lock in desired traits. Molecular marker testing now allows breeders to map heterozygosity across the genome a