Genetic markers unlock cannabis flowering secrets for precision breeding

This groundbreaking study maps the genetic and physical traits that determine when cannabis plants flower, using data from 25 Iranian landrace populations and over 145 individual plants. Researchers collected weekly measurements of plant characteristics—including stem diameter, height, and chlorophyll levels—alongside 233,624 genetic markers to understand how different cannabis varieties respond to seasonal light changes. By combining genetic analysis with real-world growth data, scientists identified 53 key markers that reliably predict whether a plant will auto-flower, flower early in the season, or flower late.

The research pinpointed two critical genetic regions responsible for flowering behavior: CsFTL3 on chromosome 08 and CsCFL1 on chromosome 09, both of which control how plants sense and respond to changing daylight hours. Auto-flowering varieties showed completely different genetic signatures from photoperiod-dependent plants, confirming they operate through a distinct biological mechanism. Early and late-flowering types, by contrast, share more genetic similarity, suggesting they respond to the same seasonal cues but with different timing thresholds.

These validated genetic markers represent a major breakthrough for cannabis breeders and cultivators. By identifying which genetic variants predict flowering behavior, the findings enable marker-assisted selection—allowing growers to precisely choose plants with desired flowering characteristics without waiting to observe their behavior through full growing cycles. This translates to faster breeding programs, more reliable crop planning, and better understanding of how cannabis genetics influence cultivation outcomes across different growing regions and climates."