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Growth and ectomycorrhizal formation of container-grown Douglas-fir seedlings inoculated with Laccaria bicolor under four levels of nitrogen fertilization

Summary

Published in Canadian Journal of Forestry Research 25: 1953-1961

Container-grown Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings were inoculated at the time of sowing with a Laccaria bicolor (Maire) Orton mycelial suspension produced in a fermentor. They were grown in a peat moss - vermiculite substrate under four levels of N fertilization (7.2, 14.4, 21.6, and 28.7 mg/seedling per season (N1, N2, N3, and N4, respectively)) to determine the N level suitable for both ectomycorrhizal development and seedling growth. After 18 weeks in the greenhouse, seedlings inoculated with L. bicolor had 44%, 32%, 44%, and 5% of their short roots mycorrhizal when fertilized with N1, N2, N3, and N4, respectively. Only when they were fertilized with N4 did the L. bicolor seedlings have significantly greater shoot height than the controls. For the other growth parameters, they were not significantly different from control seedlings for any of the N levels. After 18 weeks, regardless of the level of N, seedlings inoculated with L. bicolor had significantly lower N concentrations (%) and contents (mg/seedling) than the uninoculated ones. Consequently, for the same production of biomass, the mycorrhizal seedlings had taken up less N than the nonmycorrhizal ones. The efficiency of applied N, expressed in terms of produced biomass, decreased when the N fertilization increased; mycorrhizal and nonmycorrhizal seedlings did not tend to be different. The efficiency of the absorbed N also decreased with the level of applied N, but less rapidly, and tended to be greater for the mycorrhizal seedlings than for the nonmycorrhizal ones. Therefore, the mycorrhizal infection improved the utilization of the absorbed N. N3 was the best of the four N levels used, since it was the only one that maximized both the ectomycorrhizal formation and the growth of the seedlings. ln other words, a total seedling N concentration of 1.6% and a substrate fertility of 52 ppm N are appropriate to optimize both the ectomycorrhizal development and the growth of Douglas-fir seedlings.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Seeds and Forest Seedlings Production

Departmental author(s): 

Gagnon, Jean

Author(s)

GAGNON, Jean, Charles-Gilles LANGLOIS, Daniel BOUCHARD and François Le TACON

Year of publication :

1995

Format :

Paper

Keywords :

Pseudostuga menziesii, silvicultural regime, fertilization, Laccaria bicolor, inoculum, nutrient content, nitrogen, phosphorus, potassium, container, seedling growth, production de plants, production de semences et de plants, seeds and forest seedlings production, Douglas fir, Douglas taxifolié

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