Interpopulation variation in seed dormancy of <i>Dipterygium glaucum</i>

Dipterygium glaucum is a widespread plant in the sandy desert ecosystem; however, we have minimal information on its seed ecology. This study investigated the effects of scarification, temperature (25/15, 30/20 and 35/25°C), and light (12 hours light and 24 hours dark) on dormancy break and germination of its seeds collected from three populations in the United Arab Emirates. The imbibition curves exhibited varying patterns across the seeds of the studied populations, with little differences observed between intact and scarified seeds. Fresh scarified seeds germinated in significantly higher proportions than intact seeds among the tested temperature treatments. D. glaucum from two populations have a continuum of non-dormant (ND) and dormant (D) seeds, while the third population only have dormant seeds. Since scarification weakens physiological dormancy (PD), especially non-deep PD, we inferred the proportions of dormant seeds likely to possess non-deep PD. Neither light nor dark conditions strictly promoted or inhibited germination substantially at any tested temperature regimes, indicating the species is well adapted to the fluctuating climatic conditions of arid desert ecosystems. Interpopulation variations in seed germination suggest plants may have microclimate-based regeneration strategies, highlighting the need to consider these variations in seed traits for effective restoration.