Poster Pitches Australian Microbial Ecology 2022

Biocrust cyanobacteria improve the performance of native plants on Pilbara saline soils (#8)

Nathali Machado de Lima 1 , Frederick Dadzie 1 , Mark Ooi 1 , Miriam Muñoz Rojas 1 2
  1. BEES, University of New South Wales, Sydney, New South Wales, Australia
  2. Department of Plant Biology and Ecology, University of Seville, Seville, Spain

High soil salinity is a major environmental problem in many regions, particularly in drylands. Salinity and osmotic tension are commonly related to negative effects on plant growth and germination, being one of the biggest challenges in post-mine rehabilitation in arid regions. The use of organic and inorganic amendments to restore soil health and functionality is being broadly implemented as a remediation technology. But recently other strategies involving microbial-based technologies are also being harnessed in the context of ecosystem restoration. Cyanobacteria are phototrophic bacteria able to survive in extreme environments. They have been applied as biofertilizers (inoculants and primers) in several crops, as they can promote nitrogen fixation, germination and plant growth, among other benefits. Mixed cyanobacterial cultures from biocrusts have been successfully inoculated into post-mine substrates in the region of Pilbara (WA), showing their ability for improving soil fertility and native plant growth. Their several ecological and biological functions and the previously proven ability in remediating salt-affected soils make them a potential candidate for the promotion of germination and growth of key species used in arid land restoration in the Pilbara region. In our study, a mixed cyanobacterial culture at a concentration of 5g l-1 was applied in two different seed enhancement approaches, i.e., seed biopriming and pelletization, in four Australian native plants, i.e., Triodia epactia, Triodia pungens, Acacia ampliceps and Canavalia rosea. The seeds were sown in six different soil substrates, with different levels of salinity. In the seed biopriming experiment, the substrate with the lowest salinity content (electrical conductivity of ~ 1 mS) showed three times higher emergence and seedling biomass growth compared to the control (non-bioprimed), while seedling emergence was poor for all the other treatments. In the pelletization experiment, emergence was 7-fold higher for Acacia growing in moderate saline soils (electrical conductivity of ~ 5.7 mS), also resulting in enhanced seedling growth for Canavalia in the low and moderate saline soils. In conclusion, Australian native species under salinity can present a better performance when inoculated with native cyanobacteria, reinforcing the potential of cyanobacteria as biofertilizers also in the context of drylands restoration.