Myriad reductionist analyses have demonstrated that the response of plants to shared resources from co-evolved microbiomes can result in adaptive phenotypic changes, stress mitigation, as well as improved plant immunity through direct and indirect mechanisms. This presentation will showcase research that provided an assessment of select microbial endophyte consortia for use in improving native conifer seedling growth and development. We evaluated Pseudotsuga menziesii and Thuja plicata seedlings, established and grown under greenhouse conditions, and through simulated field testing, to determine if colonized plants have improved establishment potential when subject to common edaphic stressors including drought and nutrient deficiency.
Our experimentation determined that following approximately 1-year post-inoculation, seedlings of both species demonstrate the maintenance of significantly (p<0.05) higher physiological performance potential versus the control (mock-inoculated) seedlings. Specifically, chlorophyl fluorescence and content were maintained at higher levels among innoculated plants throughout the increase duration of induced stress events at the plant level. If inoculation took place prior to sowing, seedling morphology was significantly different (p<0.05) from control plants, with greater lateral root growth among P. menziesii seedlings, and increased branching among T. plicata seedlings. Improved drought tolerance was demonstrated for both species. Further, evidence from the trials suggests that a healthy seedling nutritional status may be the catalyst for improved plant growth and development when select microbial endophytes are present in P. menziesii. Thus, successful inoculation of widely used conifer species with endophytes holds promise for increasing forest productivity and reforestation efficiency; particularly through a decrease in mortality and possible improved resistance to drought or nutrient deficiency in soils. The results of this trial will inform nurseries, restoration ecologists, and the reforestation industry on the potential benefits of acquiring and deploying endophytes for improving reforestation success in coniferous systems. Given our promising findings, more research is necessary and implored in order to acquire and evaluate microbial endophyte consortia for a greater variety of species, and for use in stress mitigation for a greater diversity of difficult planting site conditions.