Germination of Larrea divaricata Cav, an important shrub species to restore desertified arid ecosystems

Abstract

Knowledge of pre-germination seed treatments is critical for ecological restoration practices such as outplantings or direct seeding. However, in drylands, there is a lack of this kind of information about some species with high potential value for ecological restoration. This is the case of Larrea divaricata Cav., a native species that is dominant and can grow in degraded environments to the Monte region and arid ecosystems in Argentina. We evaluated the effects of the following treatments to break seed dormancy in this species: 1) alternation of soaking and drying periods; (2) periods of soaking and rinsing with running water; (3) mechanical scarification, and (4) control. Seed scarification was done using a novel mechanical method using two pieces of sandpaper: one fixed and the other spun using a 710 W hand drill. The variables evaluated were: (a) germination percentage (over time since imbibition and the final percentage), (b) mean time to germination, and (c) number of days before the start of germination. The mechanical scarification treatment improved all germination variables compared to the other treatments. In the mechanical scarification treatment, germination percentage was 60.7%; mean time to germination was 6.32 days, and the number of days before the start of germination was 2 days. Our results indicate that mechanical scarification is an appropriate technique for propagation of L. divaricata Cav. for large scale restoration, since many seeds can be treated quickly and this technique is easily replicable.