Heterozygous Vs Homozygous

Heterozygous and homozygous refer to the genetic makeup of individual alleles at a locus. A homozygous plant carries two identical alleles for a trait (e.g., AA or aa), while a heterozygous plant carries two different alleles (e.g., Aa). In cannabis breeding, homozygous lines are prized for stability—they produce offspring expressing the same traits consistently across generations. Heterozygous plants often display hybrid vigor and may show phenotypic dominance, but their offspring segregate unpredictably unless the breeder stabilizes the line through selective breeding.

Breeders pursuing stable F1 hybrids often cross two homozygous parent lines to produce uniform, heterozygous F1 seed. Conversely, breeders developing true-breeding cultivars work to drive lines toward homozygosity across key loci, typically through repeated selfing or backcrossing to lock in desired traits.