Quantitative Genetics

Quantitative genetics examines traits controlled by multiple genes working together, rather than single-gene inheritance patterns. In cannabis breeding, most commercially important characteristics—plant height, yield potential, cannabinoid ratios, and terpene profiles—are polygenic traits influenced by numerous loci and environmental factors. Breeders working with quantitative traits rely on selection across generations to shift population averages toward desired phenotypes, as these traits typically show continuous variation rather than discrete categories. Understanding quantitative inheritance helps explain why backcrossing or stabilizing lines requires careful phenotypic assessment and multi-generational commitment. This contrasts with Mendelian genetics, which tracks single traits like seed color or plant sex through predictable ratios.

Breeders leverage quantitative genetics principles through mass selection, pedigree analysis, and controlled crosses to gradually concentrate favorable alleles across multiple trait loci. Genomic tools increasingly allow breeders to identify and track marker-assisted selection for polygenic traits, accelerating the development of stable cultivars.