Optimal gamma-ray doses for inducing mutation in cannabis sativa L. cultivars at different growth stages

Gamma (γ)-ray-dependent mutagenesis has not been fully established in cannabis. Hence, in this study, we aimed to determine the optimal γ-ray doses for inducing mutations in cannabis seeds and plants at the vegetative and reproductive stages.

The γ-irradiation ranging from 0 to 200 Gy was used to determine the optimal doses for three cannabis cultivars (CBGambit, Superwoman S1, Spectrum 303) at seeds, vegetative and reproductive stages. We examined several growth parameters (e.g., fresh weight, plant height, and number of leaves, seeds, and inflorescences) and performed linear regression analyses.

The optimal γ-ray dose by investigating growth parameters in seeds was determined to be 125 Gy (50% reduction dose, RD₅₀) for 24 h. At the vegetative and reproductive stages, the optimal γ-ray doses were found to be 75 Gy and 55 Gy (RD₅₀) for 24 h, respectively.

Our findings will greatly progress the establishment of mutant cannabis populations and cannabis breeding research. Especially, growth parameters vary depending on the developmental stage of the cultivar, and corresponding RD₅₀ doses can be applied accordingly. This detailed dose information will be helpful in cannabis mutation breeding to enhance desired traits such as specific cannabinoid content or biomass.