Open Collections

Goli, Richita

University of British Columbia

Improving nitrogen availability via biological mechanisms is essential for sustainable forestry, especially in ecosystems where nutrients are limited. Endophytic nitrogen-fixing bacteria, which can inhabit plant tissues, provide a natural and environmentally friendly substitute for chemical fertilizers, promising to enhance seedling growth and ecosystem resilience. This research examines the impact of the bacterial endophytes Caballeronia sordidicola LS-S2c and Paenibacillus polymyxa P2b-2r, individually and in combination on the growth of lodgepole pine (Pinus contorta) seedlings in nutrient-deficient environments. These seeds were treated with bacterial inoculations and evaluated for growth promotion, nitrogen fixation, and microbial colonization in the rhizosphere and endosphere (roots, shoots, needles) in a greenhouse trial after 90 (1st harvest) and 135 days (2nd harvest). Inoculation with LS-S2c significantly increased both root (46%, p<0.01) and seedling length (33%, p<0.01) when compared to the uninoculated controls, while the combined treatment (LS-S2c + P2b-2r) further enhanced various seedling growth parameters, such as root length (37%, p<0.01) and shoot biomass (48%, p<0.05), shoot height (18%, p<0.05), Seedling length (37%, p<0.01), Seedling biomass (49% p<0.05) during 2nd harvest. Although both bacterial strains were found in the rhizospheric and endophytic environments except P2b-2r in needles, nitrogen fixation was mainly attributed to LS-S2c, as indicated by the higher foliar nitrogen content in the LS-S2c treated seedlings measured at the 2nd harvest. The greatest improvements in seedling nitrogen content occurred with bacterial co-inoculation (50% N derived from atmosphere, p<0.05), indicating an associative relationship between the two strains compared to the control. These results emphasize the promise of endophytic diazotrophs as biofertilizers for use in forestry. Nonetheless, the variations in host-specific responses and the temporal changes in bacterial effectiveness underscore the necessity for extended studies to enhance bacterial inoculant approaches for sustainable reforestation and ecosystem recovery.

Text

2025-01-03

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90036

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/