Test Cross

A test cross is a breeding technique where an individual displaying a dominant phenotype is crossed with a homozygous recessive individual to determine the genotype of the dominant parent. In cannabis breeding, test crosses help breeders identify whether desirable traits are homozygous (pure-breeding) or heterozygous (carrying recessive alleles). This method is foundational in establishing stable lines and understanding hidden genetic variation within parent stock. Test crosses are particularly valuable when working with complex traits like plant structure, flowering time, or cannabinoid ratios, where visual inspection alone cannot reveal complete genetic composition. By observing offspring ratios, breeders can make informed decisions about which plants to retain for further selection and line stabilization.

Breeders use test crosses to validate breeding stock before committing to multi-generational selection programs. The technique provides genetic clarity that allows breeders to predict offspring consistency and identify plants suitable for foundation breeding or F1 hybrid production.