Local and non-local soil microbiota impede germination of the endangered Acacia whibleyana

Inoculating soils with microbiota that benefit the germination and growth of endangered plant species could improve their revegetation success and conservation status. While ecosystem degradation can disrupt beneficial plant– soil-microbial interactions, the prospect of reintroducing native plant-associated soil microbiota during revegetation could help to restore these important eco-logical links and assist the recovery of key species. We address the role of soil microbiota on germination and seedling fitness traits of the endangered Acacia whibleyana (Fabaceae) through a 17-week greenhouse experiment. Soil treat-ments included local soil, potting medium, three inoculation ratios (3:1, 1:1, 1:3 local soil: potting medium), sterilized local soil and sterilized potting medium. Soil sterilization reduced the time to first seed germination, indicating a role of soil microbiota on germination. The 1:1 whole soil inoculation saw reduced germina-tion rates compared with either pure local or potting-medium treatments, and the slower germination times observed in live soils confirmed the strong influence of soil microbiota on the timing of germination. We report evidence that poor inocu-lation strategies can adversely impact germination of this endangered Acacia. Furthermore, our findings suggest that careful assessment of microbiota asso-ciated with A. whibleyana could help to improve germination and recruitment during its revegetation and conservation management.