Endomycorrhizal inoculation improves the City of Montreal nursery tree seedling production.

CHAPDELAINE, ANNE¹, YOLANDE DALP², CHANTAL HAMEL¹, MARC ST-ARNAUD ³, SONJA KOSUTA¹, MAURO PEZZENTE¹, PIERRE JUTRAS³, SUSAN PARENT⁴.

¹Natural Resource Science Department, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue (Qc) H9X 3V9; ² CRECO, Agriculture and Agri-Food Canada, Ottawa (On) K1A 0C6; ³Botanical Garden, City of Montreal (Qc) H1X 2B2; ⁴Premier Tech, 454 Chemin TÈmiscouata, RiviËre-du-Loup (Qc) G5R 4C9 CANADA.

The production of urban trees requires approximately 10 years in QuÈbec, Canada. In an attempt to reduce production costs, 720 seeds each of Acer saccharinum, A. platanoides, Celtis occidentalis, Fraxinus pensylvanica and Gleditsia triacanthos were inoculated with Glomus aggregatum, G. etunicatum, G. intraradices, G. mosseae, G. versiforme or were not inoculated, and seedlings were fed with a fertilizer mix containing 30%, 60% or 100% of the phosphorus (P) level normally used in production. After one year of growth in the greenhouse, trees were transplanted in the field. In the greenhouse, the high P level did not reduce root colonization whereas low P levels reduced tree trunk diameter. G. versiforme, G. aggregatum and G. etunicatum increased the proportion of roots with diameters less than 2.5 mm in A. platanoides. A. saccharinum inoculated with G. etunicatum had reduced proportion of very fine roots (less than 0.3 mm) and increased proportion of root with 0.3 to 0.45 mm diameter. Inoculation had no effect on tree growth in the greenhouse but, two months after transplantation in the field, mycorrhizal G. triacanthos growth rate was 2 to 5 times larger than that of the non-inoculated controls.