Effects of nitrogen fertilization and photoperiod on basidiome formation of Laccaria bicolor associated with container-grown jack pine seedlings

Container-grown jack pine (Pinus banksiana) seedlings were inoculated with a wild strain of the ectomycorrhizal fungus Laccaria bicolor. Seedlings were raised for 24 weeks and were given various nitrogen fertilization levels as well as long and short day regimes. Basidiomes occurred from week 16 up to the end of the experiment (24 weeks) depending on the culture conditions. Frequency of fruiting reached a maximum with the addition of 5-6 mg of nitrogen per seedling. The response of fruiting to nitrogen was enhanced with a short photoperiod. The biomass of the basidiomes was positively correlated with the biomass of their respective host plants with proportions ranging from 10 to 35% and with a mean of 20%.