View article

Bacterial colonization and growth responses of hybrid spruce (Picea glauca×engelmannii) seedlings after inoculation with plant growth-promoting rhizobacteria (PGPR) were evaluated in controlled environment and field assays. Six antibiotic-resistant bacterial strains belonging to the genera Bacillus and Pseudomonas were used as inocula. For controlled environment assays, surface sterilized seeds were inoculated with log 6 Bacillus or log 8 Pseudomonas colony-forming units (cfu) under gnotobiotic conditions for assessment of rhizosphere and internal root and stem tissue colonization. In the field trial, one-year-old, container-grown hybrid spruce seedlings were inoculated with each of the Bacillus or Pseudomonas strains 1–2 days before planting at nine field sites in British Columbia and Alberta, Canada. All six strains colonized the rhizosphere with log 5.6−7.6cfug⁻¹ root tissue under controlled environmental …