b) The role of soil microbes in tallgrass prairie restoration – Rachel Becknell, Washington University
Interactions between plant species and their species-specific soil microbes may play a crucial role in how plant communities are structured. In recent years, there has been a greater emphasis on the restoration of soil microbial communities, as soils have been shown to harbor significantly different microbial communities depending on the successional stage of the ecosystem and land-use history. In a greenhouse experiment looking at soil microbes effects on 18 different tallgrass prairie species, I found that most species are strongly affected by negative interactions with their own soil microbes but can escape these microbes when growing in soil from more distantly related species. This interaction, known as negative plant-soil feedback, has the potential to play an important role in the coexistence of many different plant species in one place. In a separate experiment, I tested the importance of soil microbes from an old field where a restoration is likely to occur, a remnant tallgrass prairie, and a sterile control on the growth of two hard-to-establish tallgrass prairie species. Both plant species were grown in different plant communities that ranged from being closely related to the two species, to distantly related. They were not significantly affected by the different soil microbial treatments in the first two years but grew significantly larger when in plant communities more distantly related to them. Reducing competition for more closely related plant species is key when attempting to grow these hard-to-establish plant species in tallgrass prairie restorations.
c) Phytotechnologies for Remediation and Reclamation of High Salinity Soil – Elizabeth Murray, Earthmaster Environmental Strategies Inc.
(Fast forward to 29:30)
We have successfully developed and implemented Plant Growth Promoting Rhizobacteria (PGPR) - Enhanced Phytoremediation Systems (PEPSystems) for cost effective removal of petroleum hydrocarbons (PHCs) and salt from soils. PEPSystems utilizes soil bacteria coated on the surface of seeds to facilitate the production of abundant root biomass in impacted soils. This stimulates growth of rhizobacteria to enable degradation of PHCs, partitioning of contaminants out of the soil, and sequestration of salt into plant foliage. PEPSystems has been successfully deployed on many sites across Canada to remediate contaminated soil. This talk will discuss: 1) Earthmaster’s microbiology lab and plant growth facility completed studies with the goal of improving plant growth in phytoremediation and reclamation applications where elevated soil salinity may be a concern. These studies will examine the effectiveness of PGPR in improving seed germination rates in high salinity conditions. 2) Laboratory studies using gibberellin and L-tryptophan to enhance seed germination in high salinity conditions. 3) Growth chamber studies using both grass seed and grass plugs grown in soil containing elevated and the effectiveness of bacteria in facilitating plant growth and uptake of sodium and chloride into the plant tissues. Finally, field application case studies will be reviewed to examine the effectiveness of PGPR/plant combinations.
