Breaking Dormancy In Gmelina arborea Roxb. Through Treatment Of Seeds With Chemical Substances And Alternating Temperature

Seeds of Gmelina arborea Roxb. were subjected to different treatment [chemical scarification with concentrated sulphuric acid (H2S04), potasium nitrate (KNO3), potasium nitrite (KNO2) and alternating temperature regimes] to ascertain the best treatment for terminating dormancy in the seeds. Initial viability and germination tests showed that the seeds of G. arborea are viable but dormant. Seed viability percentage of 96 was recorded. Dormancy in the seeds was found to be the physical type caused by hard seed coat. Chemical scarification for 10 minutes with concentrated H2S04 was very effective in breaking seed dormancy in the species. This increased water uptake in the seeds to 68% compared with the 15% in unscarified seeds after 7 days. Scarification gave a germination percentage of 80 over 43% for the unscarified after 26 days. 1mM and 10mM KNO3 and KNO2 terminated dormancy and highly enhanced germination in the scarified than unscarified seeds. Alternating temperatures promoted germination of G. arborea seeds with the best results recorded at 9 cycles of alternating temperature at 30 °C for 16hours and 45 °C for 8 hours. Key Words: Dormancy, Gmelina arborea, Chemicals, Alternating temperature Bio-Research Vol.2(1) 2004: 59-6