The effect of scarification and temperature shock on seed germination and seedling length of Gundelia tournefortii L.

Gundelia tournefortii L. seeds owing to the strongly lignified disseminule from secondary capitulum, cannot germinate easily. In current study, three individual experiments were done to investigate the impact of chemical scarification (treatment with water, hydrochloric acid, sulfuric acid, acetic acid, sodium hypochlorite and hydrogen peroxide in durations of 20, 40, 60 min), physical scarification (control, scalpel, blade and 5, 10 min sand paper) and temperature shocks (individual or combined treatment with boiled water for 60 min and 1, 2, 3 days freezing on seed germination of chelgerd population. Results showed that in non-scarified seeds, germination was very low, but all mechanical scarification methods significantly increased seed germination. Among chemical scarification treatments, the highest seed germination obtained by 20 min soaking in hydrochloric acid but seedling growth was not favorable. The combined treatment of 60 min soaking in hot water and 3 days freezing, better than individual temperature shock increased germination indices, seedling length and vigor. In sum, results showed that the best method for physical dormancy breaking of kenger seeds was scarifying with scalpel that imparted the maximum germination percentage (58.46%), peak value (3.5), mean daily germination (3.2 days) and germination value (11.53).