Influence of extrinsic factors and salt stress on the in vitro germination and development of Moroccan Cannabis sativa L. varieties as potential medicinal plants

The optimization of Cannabis sativa L. germination is vital for achieving controlled and uniform cultivation, especially given its growing significance as a medicinal plant rich in bioactive compounds. Since germination strongly impacts subsequent agronomic performance, it requires specific environmental conditions. This study assessed several treatments to improve the in vitro germination of two Moroccan varieties, Beldia and Khardala, including gibberellic acid, hydrogen peroxide, temperature, photoperiod exposure, total darkness, mechanical scarification and salt stress induced by increasing concentrations of NaCl (0, 42.8, 85.5, 171.1, 256.6 and 513.3 mM). Each treatment was performed on a large number of seeds per variety and results were analysed using two-way ANOVA followed by Duncans’ test with P < 0.05. Results revealed that photoperiod exposure moderately stimulated germination (50 %), while hydrogen peroxide (1.5 %) increased it to 77.7 % by reducing the level of abscisic acid, which is responsible for germination inhibition. Gibberellic acid (1.2–1.4 mg/L) further enhanced germination to over 80 % by inhibiting embryonic dormancy and stimulating hormonal pathways. Low-temperature treatment (5 °C) yielded an 83 % germination rate. Mechanical scarification was the most effective method, achieving approximately 90 % germination. In contrast, salinity stress progressively inhibited germination: at 513.3 mM NaCl, germination dropped to 20 % in Khardala and 0 % in Beldia. Seedling growth, including shoot and root length, leaf number and fresh and dry biomass, was also significantly reduced, with root development particularly affected. At 85.5 mM NaCl, root growth declined by 62 % in Beldia and 88.7 % in Khardala, indicating greater salinity sensitivity in Khardala. In conclusion, optimising germination conditions and selecting salt-tolerant varieties are essential for improving the in vitro culture of C. sativa and producing plants better adapted to saline stress.