Sex Determination System

Sex determination systems in cannabis refer to the genetic mechanisms that govern plant sexuality, primarily XX/XY chromosomal inheritance in dioecious varieties. Most cultivated cannabis strains are either female (XX), male (XY), or hermaphroditic, with sex expression influenced by both genetics and environmental stress factors. Understanding these systems is foundational for breeders seeking to develop stable female-only lines, maintain genetic diversity, or study sex-linked trait inheritance. Historical breeding records show significant variation in sex determination stability across different landrace populations and modern cultivars. Environmental conditions—including photoperiod, temperature, and nutrient balance—can trigger sex reversal or hermaphroditism even in genetically stable lines, complicating controlled breeding programs.

Breeders select for stable female-only phenotypes through recurrent selection and often employ feminized seed production techniques to ensure consistency in commercial breeding. Understanding sex determination helps geneticists map sex-linked traits, predict offspring ratios in crosses, and develop cultivars with predictable reproductive behavior.