Karrikinolide Maximises Seed Use Efficiency for Ecosystem Restoration and Nature Repair

Ecological restoration and nature repair combat ecosystem and land degradation, biodiversity loss and climate change. Yet seedling recruitment failure and perilously low plant survival (6–11%, often less) result in mass seed wastage. To increase seed use efficiency for restoration, the germination stimulant karrikinolide or KAR1 (3-methyl-2H-furo[2,3-c]pyran-2-one) was evaluated for on-demand seed germination, seedling establishment and plant survival in Australian core restoration species. Our research demonstrated that KAR1 promoted on-demand germination in 82% of species across nine families. We also showed improved germination outcomes in stored and aged seeds and greater seedling establishment and plant survival in soil after KAR1 treatment. The commercially available stimulant, gibberellic acid (GA3), provided no assistance beyond seed germination, suggesting KAR1 cannot be readily substituted. We recommend that KAR1 has the potential to meaningfully enhance large-scale seed use efficiency for restoration once challenges like cost and KAR1 delivery issues are overcome.