Seed-based restoration is the most widely used and spatially feasible approach to confront the expanding land disturbance footprint. In drylands, plant establishment is restricted to narrow recruitment windows, delineated by precipitation and temperature conditions that are suitable for plant germination, establishment, and survival. In the arid Pilbara bioregion of northwest Australia, plant recruitment is driven by both precipitation event size and moisture availability. The demographic transition between a seed and adult plant is most constrained during the germination and emergence phases of the plant development, with 90-95% of seeds losses experienced during this period. These bottlenecks in recruitment are driven by seed dormancy, characteristic of more than 80% of dryland floras, and the hydrothermal germination requirements of the seeds. Reliable methods for seed dormancy alleviation combined with seed enhancement technologies – defined as treatments tailored to improve performance in field conditions – are critical to increasing plant re-establishment potential. Here we focus on the Pilbara bioregion of Western Australia, where mining plays a major role in plant community degradation, with the current disturbance footprint exceeding 230,000 ha. Through a series of trials using a dominant, but difficult to establish endemic grass species, Triodia pungens, we set out to understand whether coupling seed dormancy alleviation (removal of floral appendages and exposure to a smoke-derived compound, karrikinolide [KAR1]) with seed enhancement (hydropriming and seed coating) can increase the total fraction of seeds that complete the germination and emergence phases of plant development, resulting in higher plant establishment. Secondly, we aimed to determine whether these treatments could improve growth and survival across an aridity gradient.
Results/Conclusions
Overall, we found that removal of floral appendages and hydropriming with KAR1 could significantly (P < 0.05) improve germination, emergence, and enhance seedling development across a suite of moisture conditions. Detailed findings of the laboratory, controlled climate facility, and field-based trials will be presented.