Test Crosses

Test crosses are breeding experiments where a plant with a dominant or unknown phenotype is crossed with a homozygous recessive individual to reveal hidden genetic traits. Breeders use test crosses to identify recessive alleles, confirm genotypes, and understand the genetic architecture of desired traits like cannabinoid production, terpene profiles, or plant structure. This classical genetics technique predates modern DNA sequencing and remains foundational in cannabis breeding programs. Test crosses help stabilize new cultivars by mapping which genes are expressing visibly versus remaining masked. The results inform decisions about which plants to select for subsequent generations and breeding direction.

Breeders rely on test crosses to decode the genetic makeup of promising phenotypes before committing resources to multi-year selection programs. By crossing a candidate plant against a known recessive or homozygous line, breeders can predict offspring outcomes and identify whether desirable traits will breed true in future generations.