Quantitative Trait Loci

Quantitative Trait Loci (QTL) refers to chromosomal regions containing genes that influence polygenic traits—characteristics controlled by multiple loci rather than a single gene. In cannabis breeding, QTL mapping helps identify genomic segments associated with complex traits like cannabinoid yield, terpene profile composition, plant height, and flowering time. Rather than governing one specific terpene, QTL research maps the genetic architecture underlying quantitative variation in aromatic and chemical phenotypes. Understanding QTL positions allows breeders to select parent plants more strategically and predict offspring trait expression with greater accuracy. This approach represents a shift from classical single-trait selection toward genomics-informed breeding programs.

Breeders use QTL identification to accelerate trait stabilization in multi-generational programs, particularly when targeting complex phenotypes that don't follow simple Mendelian inheritance patterns. Marker-assisted selection (MAS) leveraging QTL data enables more efficient culling and crosses, reducing time to fix desirable quantitative trait combinations.