Modulating the phytochemistry of Cannabis sativa L. through controlled cultivation practices

Cannabis sativa L. is a multifunctional crop of increasing economic and medical importance, characterized by the production of specialized metabolites, primarily cannabinoids and terpenes, concentrated in glandular trichomes of female inflorescences. While genetic factors largely determine chemotype, environmental conditions and cultivation practices strongly modulate both yield and chemical composition. In the context of Controlled Environment Agriculture (CEA), understanding and standardizing how cultivation factors shape metabolite accumulation is fundamental to ensure product consistency for pharmaceutical use. This dissertation explores the interaction between genetics, cultivation environment, stress management, and post-harvest processing in determining the phytochemical composition of cannabis. The central goal is to define agronomic strategies capable of enhancing secondary metabolism while maintaining reproducibility and biomass productivity in soilless cultivation systems, particularly hydroponics and aeroponics. The first chapter gives a general overview about the Cannabis sativa plant, from its taxonomy, morphology and history, till the many uses and properties. It also provides a background on the cultivation practices and the importance of CEA for the standardization and better understanding of this plant cultivation and needs. The second chapter provides a genetic and phenotypic characterization of European commercial seed lots using SSR markers, highlighting significant variability in genetic uniformity and population structure. These results point out the need for reliable genotyping tools to authenticate varieties and stabilize germplasm for medical production. The third chapter investigates within-plant distribution patterns of secondary metabolites, showing clear positional gradients in cannabinoids and terpenes between apical and lateral inflorescences. These findings emphasize the importance of canopy management and selective harvesting to reduce intra-plant variability. Complementary analysis of our own cultivation trials confirmed that apical buds consistently contained higher levels of several cannabinoids than lateral buds, and Principal Component Analysis (PCA) of terpene profiles revealed distinct clustering of apical versus lateral samples. The fourth core chapter tested water stress regimes in CBD-dominant genotypes. Results demonstrated that moderate, well-timed water deficits could stimulate secondary metabolism and increase cannabinoid accumulation, but excessive or poorly timed stress negatively impacted biomass and inflorescence yield. This identifies critical thresholds and developmental windows for applying stress as a tool to modulate phytochemistry. The fifth chapter examined nutrient solution composition and concentration in aeroponic high-THC cannabis. Differences in ion supply significantly influenced biomass allocation, cannabinoid content, and terpene profiles, with distinct cultivar-dependent responses. Nutrient concentration shaped both the plant ionome and the accumulation of major cannabinoids, underlining the role of mineral nutrition as a control for optimizing secondary metabolism in soilless systems. The final experimental chapter addressed post-harvest processing, specifically drying and steam distillation. Terpene composition was highly sensitive to processing method: drying altered the relative abundance of monoterpenes and sesquiterpenes, while distillation led to substantial losses of volatiles compared to the fresh material. These findings have direct implications for preserving organoleptic and pharmacological qualities in medical cannabis production chains. Collectively, this thesis demonstrates that the phytochemistry of Cannabis sativa arises from a dynamic interaction between genotype and controllable agronomic factors, including canopy structure, irrigation strategy, nutrient management, and processing.