Investigating the application of microbial amendments in Australian native plant restoration work

Soil microorganisms can improve plant health, seedling emergence and growth. Therefore, seed coatings, incorporating microbial amendments, may improve restoration outcomes for native Australian plant species. To assess effectiveness of a suite of different amendments (Vermiwash, Metagen, MycoGold and native soil inoculum) added to AirSeed Technologies’ Seed Pods, two glasshouse trials were conducted for which seeds were sown in soil collected from a restoration site in the Sydney region (Mount Annan) in trial one, and in a microbially-depauperate, autoclaved soil during trial two. Seeds of three Australian native plant Species were bare seeded or encapsulated in amended and non-amended AirSeed Technologies’ Seed Pods. Seedlings were monitored for three months. In the microbially-depauperate soil, growth rates and total dry biomass of seedlings in the native soil Seed Pods were significantly higher compared to non-amended Seed Pod controls (Acacia parramattensis and Hardenbergia violacea) and bare seeds (Acacia parramattensis). None of the amended Seed Pods significantly improved root nodule formation, root:shoot dry biomass ratios, or emergence across all species in both growth media. These results suggest Seed Pods made with native soil provided additional growth benefits in the microbially-depauperate soil relative to non-amended Seed Pods and bare seed controls. Nevertheless, the use of microbial amendments and the application technique may need to be refined to meet specific needs of Australian native plant species and soil characteristics.