Test Crossing

Test crossing refers to the breeding practice of crossing a plant with a homozygous recessive individual to reveal hidden recessive alleles in the tested parent. In cannabis genetics, breeders use test crosses to identify whether desirable phenotypic traits are homozygous (true-breeding) or heterozygous (will segregate in future generations). This technique is foundational in establishing stable cultivars and understanding the genetic architecture underlying morphology, terpene profiles, and other heritable characteristics. Test crosses are particularly valuable when working with limited seed stock or when attempting to isolate and stabilize novel trait combinations. The practice requires patience and careful record-keeping across multiple generations to accurately assess genetic contributions.

Breeders employ test crosses to validate whether selected individuals can reliably transmit desired traits to offspring. This approach is essential for making informed decisions about which plants to advance in breeding programs and which to cull from further development.