Effect of Bacillus strains on growth of pine (Pinus contorta Dougl.), spruce (Picea glauca Voss.), and Douglas-fir (Pseudotsuga menziesii (Mirb. Franco)

Abstract

Bacteria that are applied to seeds, roots, or tubers and subsequently colonize roots and enhance plant growth have been termed plant growth promoting rhizobacteria (PGPR) (Kloep-per et al., 1980). PGPR have been studied extensively in agricultural systems and have been shown to promote growth of various deciduous species. (Caesar and Burr, 1987). However, little work has been done describing PGPR effects on coniferous forest species. We have tested the effects of two Bacillus strains previously demonstrated to promote growth of forage species (Holl et al. 1988; Chanway et al., 1988). Bacterial strains were grown in nutrient or tryptic soy broth, harvested by centrifugation, and resus-pended in phosphate buffer. A small volume of the suspension (ca. 108 cells) was added to seed or seedlings in containers of a peat/venmiculite mixture. Seedling were grown under artificial light in growth chambers.