Germination of Prosopis laevigata (Humb. et Bonpl. ex Willd) seeds subjected to pre-germination treatments under two environmental conditions

Mesquite (Prosopis laevigata Humb. et Bonpl. ex Willd) seeds have hard coats. This limits the imbibition and slows the germination rates and, as consequence, restricts the natural regeneration of its populations. Soaking in hot water is one of the most effective methods for breaking the physical dormancy of mesquite seeds. However, what is still being debated is the optimal soaking time and the effectiveness in real growth conditions. In this study, the aim was to evaluate the effect of soaking time in hot water (90 °C) on mesquite seeds germination under two environmental conditions (germination chamber and greenhouse). Six treatments were considered in both conditions. The treatments consisted of scarifying seeds by soaking them in water at 90 °C at different times of 1 to 5 min, plus a control (i.e. a seed lot without soak). The highest germination percentages (84.0% and 81.4% in the germination chamber and greenhouse, respectively) occurred in seeds soaked for 1 min in both environments. This treatment caused the highest germination percentages. Seeds without pre-germinative treatment (control) caused the lowest germination percentages in both environments (35.0 and 53.3% in the germination chamber and greenhouse, respectively). The effect was similar in both environmental conditions, although the germination rate was faster in the germination chamber than in the greenhouse. These results show that scarification with hot water (90 °C) for 1 min enhances the germination potential of mesquite seeds. The study has practical implications for improving nursery cultivation protocols of P. laevigata seedlings.