New insights on flowering of Cannabis sativa

The main product of medical cannabis is the female inflorescence with thousands of glandular trichomes that produce and accumulate bioactive specialized metabolites. Although non-scientific public knowledge is largely available, in-depth research of cannabis flowering is limited. Growth under long photoperiod is considered "vegetative", however, the development of solitary flowers in the shoot internodes during that stage clearly indicates that the plant is not vegetative nor non-inductive in the classical sense. Nevertheless, a short photoperiod is required for the development of an inflorescence structure. This structure consists of the same basic phytomers that develop under a long day stage. Inflorescence development is characterized by a reduction in branchlets length, an increase in internode density and a clustering of solitary flowers. We demonstrate that the photoperiod signal induces inflorescence development within the first five days of short day exposure. Future understanding of the genetic and physiological mechanisms governing inflorescence development will lay the foundations for horticultural and biotechnological applications to modify the architecture and maximize plant productivity and uniformity in medical cannabis.