Growth and ectomycorrhiza formation of container-grown red oak seedlings as a function of nitrogen fertilization and inoculum type of Laccariabicolor

Containerized red oak (Quercusrubra L.) seedlings were inoculated at the time of sowing with Laccariabicolor (Maire) Orton using two methods to compare the efficiency of two inoculum types: a mycelial suspension (Ecot-Sol®101) produced by Rhizotec Laboratories Inc. and calcium alginate beads containing this mycelial suspension. Red oak seedlings were also grown for 19 weeks in a peat moss – vermiculite substrate under three levels of N fertilization (100, 120, and 140 mg/seedling per season) to determine the N level that maximizes the ectomycorrhizae formation and growth of seedlings. After 19 weeks in the greenhouse, seedlings inoculated with liquid inoculum had significantly more mycorrhizae than both those inoculated with beads and controls, regardless of the N level. For any of the N levels, liquid-inoculated seedlings had significantly lower shoot height, root-collar diameter, and dry weights (shoot, root, and total) than both those inoculated with beads and the controls, whereas there were no signif...