Growth of Outplanted Lodgepole Pine Seedlings One Year After Inoculation with Plant Growth Promoting Rhizobacteria
Four-month-old lodgepole pine seedlings were inoculated with plant growth promoting rhizobacteria (Bacillus polymyxa strain L6-16R) and outplanted at one interior site (Gavin Lake) and two coastal sites (University of British Columbia South Campus and Totem Field) in British Columbia. The percentage of seedlings that incurred overwinter injury and that survived 13 months after outplanting were not influenced by bacterial inoculation. At Totem Field, where growth of control seedlings was greatest, inoculation had an inhibitory effect on seedling performance. At South Campus, where growth of control seedlings was intermediate compared with seedlings at Totem Field and Gavin Lake, inoculation had a slight stimulatory effect on seedling performance, but bacterial effects were not significant. However, at Gavin Lake, where seedlings attained only 14% of the biomass of those grown at Totem Field, inoculated seedlings had significantly increased stem diameter (7%), root dry weight (32%), and shoot dry weight (33%). While the effects of site history and site quality were confounded in this study, these results suggest that inoculation of lodgepole pine with strain L6-16R may be useful for seedlings targeted for outplanting on relatively harsh or poorer quality sites, but less so for seedlings to be planted at higher quality sites. For. Sci. 40(2): 238-246.
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