Quantitative Genetics

Quantitative genetics describes the inheritance of traits controlled by multiple genes, each contributing small additive effects to the final phenotype. Unlike single-gene traits, quantitative traits show continuous variation across a population—such as plant height, yield potential, or terpene ratios—rather than discrete categories. In cannabis breeding, quantitative traits are polygenic, meaning breeders must evaluate large populations and use selective breeding across multiple generations to shift trait averages. Environmental factors also influence quantitative traits significantly, making phenotypic expression variable even within genetically identical plants. Understanding quantitative inheritance helps breeders predict outcomes when crossing divergent lines and guides strategies for stabilizing desired characteristics in breeding programs.

Breeders working with quantitative traits typically employ population-level selection, progeny testing, and multi-generational evaluation to accumulate favorable alleles. Quantitative genetics frameworks inform decisions about population size, crossing strategies, and the realistic timeframes needed to establish stable cultivars with complex trait combinations.