Growth and ectomycorrhiza formation of containerized black spruce seedlings as affected by nitrogen fertilization, Inoculum type, and symbiont

Piceamariana (Mill.)B.S.P. seedlings were grown in containers under three levels of nitrogen fertilization (6, 8.5, and 15 mg/seedling per season). Seedlings were inoculated at sowing with Laccariabicolor and Hebelomacylindrosporum, using two methods: mycelial suspension liquid inoculum and peat–vermiculite solid inoculum. Results show that liquid inoculum was as effective as solid inoculum for development of Laccariabicolor ectomycorrhizae on black spruce seedlings. After 20 weeks in the greenhouse, seedlings fertilized with 8.5 mg N and inoculated with L. bicolor had the highest percentage of ectomycorrhizal short roots for both inoculum types, with 59 and 53% for liquid and solid inocula, respectively. These L. bicolor seedlings had significantly more ectomycorrhizae with 8.5 mg N than with 15 mg N. Very few ectomycorrhizae were obtained with Hebelomacylindrosporum for any of the nitrogen levels or either of the inoculum types. There were no significant differences for any growth parameters except shoo...