Cannabis yield and cannabinoid profile affected by plant nutrition and planting density

Cannabis sativa L. is widely cultivated for its medicinal and industrial uses, with increasing demand driving research on factors that influence cannabinoid yield and profile. This study examined the combined effects of individualized nutrient solutions and planting density on cannabinoid content and inflorescence yield in a soilless cultivation system. Four treatments were applied: a control (A) and three enhanced treatments (B, C, D). Treatment B received an amino acid biostimulant to potentially enhance nitrogen utilization. Treatment C provided increased phosphorus (P), potassium (K), and iron (Fe) for enhanced energy transfer and stress resilience, and treatment D combined the nutrient compositions of B and C. Nutrient solutions were refreshed weekly and analyzed to monitor elemental composition. Treatments were applied at two planting densities (9 and 27.5 plants/m2). Cannabinoids were extracted and quantified using high-performance liquid chromatography with diode array detection. The combination of P, K, and Fe in treatment C produced the highest THC concentration (12.3 %) in the inflorescences, outperforming both the control (11.2 %) and treatment D (11.9 %). In contrast, treatment B, which used only the biostimulant, had the lowest THC concentration (9.5 %). Total THC yield per plant also varied significantly. In week 9, treatment C had the highest THC yield (2.81 g), while B had the lowest (1.60 g). By week 12, both treatments C and D reached nearly identical THC yields (5.94 g and 5.97 g), with treatment B still lagging at 3.69 g. This suggests that P, K, and Fe supplementation is critical for maximizing THC yield, while the biostimulant alone was less effective. Higher planting density increased THC concentration in inflorescences but reduced individual plant biomass, while lower density resulted in higher dry inflorescence and total THC yields per square meter. This suggests that cultivating fewer plants per square meter can optimize resource access and increase yield.