News: How Light And Gibberellins Shape Cannabis Inflorescences.
- Manuel Basegla
- Sep 19
- 2 min read
Published 12:00 AM EST, Fri Sep 19, 2025
While single flowers emerge independently of light cues, condensed inflorescences require continuous short-day exposure and reduced gibberellin (GA) levels. Short days trigger shorter internodes, increased branching, and flower clustering, while long days or GA reverse this process. The findings highlight GA’s pivotal role in mediating photoperiod signaling and influencing cannabinoid accumulation.
Researchers at the Agricultural Research Organization, The Volcani Institute (Israel), have uncovered how photoperiod and gibberellin (GA) signaling jointly regulate cannabis inflorescence development. Their study, published in Horticulture Research (Sept 2024), shows that while individual flowers can emerge under any light conditions, the formation of condensed inflorescences requires continuous short-day (SD) exposure. Short days rapidly reshape plant architecture - shorter internodes, increased branching, and clustered flowers, whereas long-day (LD) conditions or external GA applications reverse these effects, leading to looser, elongated structures.
Through controlled experiments, the team demonstrated that at least three consecutive short days are needed to initiate inflorescence development, but continuous SD is essential to maintain it. Returning plants to LD caused clusters to break down into solitary flowers, while exogenous GA treatments under SD mimicked LD responses, delaying or disrupting inflorescence formation. Hormone profiling confirmed that SD lowered GA and auxin levels, correlating with compact inflorescences and higher cannabinoid accumulation. Conversely, elevated GA promoted elongation and reduced cannabinoid levels, highlighting GA’s pivotal role as a mediator of photoperiod signaling and metabolite production.
These findings provide a mechanistic explanation of how environmental cues and hormone levels interact to control cannabis reproductive morphology. The research identifies GA as a key regulator that links photoperiod to both plant architecture and cannabinoid output, bridging longstanding gaps in cannabis reproductive biology. By uncovering this relationship, the study lays the groundwork for more precise manipulation of flowering schedules, architecture, and chemical composition.
Hemp farmers can optimize harvest timing to preserve fiber quality by controlling when inflorescences initiate. Seed producers may adjust light regimes and hormone balance to maximize seed set through favorable inflorescence architecture. For medicinal and recreational cannabis, maintaining condensed flower clusters under SD conditions is crucial to achieving cannabinoid-rich yields. Understanding GA’s suppressive effect on cannabinoid accumulation also offers a new lever for cultivation strategies.
Collectively, this research empowers breeders and growers with tools to fine-tune light and hormone management, enabling more consistent, high-quality production across fiber, seed, and medicinal markets.
Source: EurekAlert!
