Breaking Seed Dormancy and Improving Seedling Growth of Encephalartos altensteinii Lehm. using Seed Hydration-dehydration Treatment and Acid Scarification

Germination rate and percent germination are low for most cycads, including Encephalartos altensteinii, thereby affecting the production and conservation efforts for this endangered plant group. Although seed germination experiments for cycads have been done mainly on Zamia and Cycas, there is limited germination research on the African genus Encephalartos. The effects of hydration-dehydration treatment on seed longevity, embryo development, moisture content and viability were studied by hydrating seeds of E. altensteinii Lehm during storage for 24 hr and dehydrating for 96 hr every month for 8 months. Simultaneously, seeds were soaked in different concentrations (0%, 10%, 25%) of sulfuric acid (H2SO4, pH 0.3) and gibberellic acid (GA3) between 0.5 and 48 hr to break dormancy. Thereafter, seeds were sown in silica-sand-filled-sowing beds in the greenhouse and monitored over eight months. Hydration-dehydration treatments had positive effects on the viability of E. altensteinii seeds stored at room temperature and that further decreases in moisture content were detrimental. Also, a combination of H2SO4 and GA3 significantly improved germination percentage whereas no significant difference was recorded in seeds treated with only H2SO4. These results suggest that seed viability and germination of E. altensteinii can be improved with hydration-dehydration and acid scarification treatments. Species used in this study: Eastern Cape giant cycad, Encephalartos altensteinii Lehm. Chemicals used in this study: Sulfuric acid, gibberellic acid, captan, 2,3,5-triphenyltetrazolium chloride.