Indigenous soil microbial inoculants promote restoration of arid plants in saline soils

Salinity is one of the challenges affecting seed germination and establishment in dryland restoration projects. Seeds must overcome the osmotic pressure present in saline soils before they can germinate. An ideal method is to reduce the osmotic potential through continuous irrigation to flush out the excess salts from the soil to enable seeds to germinate. However, such a system is impractical at scale and would exponentially increase restoration budgets. Research has shown that bacteria and cyanobacteria individually improve seedling germination. However, it is unclear whether bacteria and cyanobacteria improve seedling germination individually and as combined entities under dryland conditions. In this glasshouse study, we test the hypothesis that, inoculating seeds with bacteria, cyanobacteria and the combination of both will increase seed germination outcome compared to their none inoculated counterpart. We also examined which microbial inoculation would yield the greatest seedling germination and biomass. We found that all inoculated seeds with microorganisms significantly increased seedling emergence and biomass production compared to the non-inoculated seeds. The highest seedling emergence was found in the cyanobacteria treatment followed by the combined bacteria and cyanobacteria treatment. Similarly, the highest biomass production occurred when seeds were inoculated with cyanobacteria treatment followed by bacteria treatment. Our results suggest that, cyanobacteria can be used as a potential tool to overcome seedling germination challenges in saline dryland ecosystems during restoration.