Induction of polyploidy and its effect on cannabinoid content in Cannabis sativa L.

Polyploidy induction is a promising strategy to enhance biomass and secondary metabolite production in medicinal plants. In this study, an optimized protocol was established for polyploid induction in Cannabis sativa L. and evaluated its effects on plant morphology and cannabinoid accumulation. Colchicine treatments showed the highest induction efficiency, and 0.5 mM for 24 h was identified as the optimal condition. A colchicine-induced mixoploid plant (S80) was self-pollinated to generate stable triploid, tetraploid, and hexaploid plants, which were confirmed by flow cytometry and chromosome counting. Hexaploid plants exhibited the largest stomata and the highest total cannabinoid content, with approximately 65 % greater accumulation than diploids. Growth performance and floral biomass were also markedly improved in hexaploids: plant height increased by ∼60 %, stem diameter by 14 %, and inflorescence dry weight by 2.7-fold compared with diploids. These findings demonstrate that colchicine-mediated polyploid breeding can significantly improve both biomass and cannabinoid yield, highlighting hexaploids as a valuable resource for industrial and pharmaceutical applications. • Efficient colchicine-induced polyploidy protocol optimized in Cannabis sativa . • First confirmation of stable hexaploid cannabis using flow cytometry and karyotyping. • Enhance floral biomass, stem growth, and cannabinoid accumulation in hexaploids. • Increase total cannabinoid content with higher ploidy, especially Δ 9 -THC and CBG. • Provide a promising strategy for breeding high-yield medicinal cannabis.