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 gro wth promoting rhizobacteria (Bacillus polymyxa strain L6-16R) and outp lanted at one interior site (Gavin Lake) and two coastal sites (Univer sity of British Columbia South Campus and Totem Field) in British Colu mbia. The percentage of seedlings that incurred overwinter injury and that survived 13 months after outplanting were not influenced by bacte rial inoculation. At Totem Field, where growth of control seedlings wa s greatest, inoculation had an inhibitory effect on seedling performan ce. At South Campus, where growth of control seedlings was intermediat e compared with seedlings at Totem Field and Gavin Lake, inoculation h ad 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, inocul ated seedlings had significantly increased stem diameter (7%), root dr y 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 u seful for seedlings targeted for outplanting on relatively harsh or po orer quality sites, but less so for seedlings to be planted at higher quality sites.