Synergistic effects of hydropriming and differential gamma radiation on the physiomorphic attributes of Cannabis sativa L.

PURPOSE: This study evaluated the impact of hydropriming and gamma rays on morpho-functional attributes of Cannabis sativa L. and identified optimal radiation levels for improvements in local hemp germplasm. MATERIALS AND METHODS: Two seed lots, G1 (pre-irradiation hydropriming) and G2 (post-irradiation hydropriming), were subjected to the radiation source cobalt-60 (Co60) at specified doses (150, 300, 450, and 600 Gy) in a completely randomized factorial experiment with 10 treatments and three replications. Key physiomorphic traits, including germination rate, survival percentage, plant height, leaf number, shoot/root dry weight, trichome traits, chlorophyll and metabolite contents (anthocyanin, flavonoids), were measured and statistically analyzed via ANOVA Tukey's HSD. Regression heat maps and dose response curves were drawn to find out optimal dose levels. RESULTS: Gamma irradiation significantly influenced all the parameters across treatments compared to wild-types. Application @150 Gy increased seed germination, survival rate, plant height, biomass, chlorophyll content, and trichome density while high doses (210.16 Gy in G1 and 425.95 Gy in G2) surpassed LD50. Maximum phenotypic variation was observed in G1D1 and G2D3. The trichome density notably increased at low to moderate doses. A significantly positive correlation was observed among parameters in response to gamma irradiation; however, dose response curves showed greater radio-tolerance and growth in G2 than G1 plants. CONCLUSION: Low-dose gamma irradiation (150 Gy) combined with hydropriming can be an effective mutagenic approach to enhance the growth and biochemical traits of Cannabis sativa. The findings offered a viable mutation protocol to develop improved hemp varieties tailored for fiber and cannabidiol (CBD) production.