Ectomycorrhiza formation and growth of Picea abies seedlings inoculated with alginate-bead fungal inoculum in peat and bark compost substrates

Sphagnum peat (peat), spruce bark compost (compost), peat +perlite (1 : 1, v : v) and compost + perlite (1 : 1, v : v)substrates were inoculated with vegetative alginate-bead inoculumof Hebeloma crustuliniforme, Hygrophorus agathosmus or Paxillusinvolutus or left uninoculated prior to the addition of Norwayspruce seed. Growth and percentage of mycorrhization of barerootseedlings cultivated in a greenhouse were evaluated after thefirst growing season. Seedlings grown in peat-based substrateshad significantly larger aboveground and total dry weight, butsignificantly lower mycorrhization percentage than those grownin compost-based substrates. There were no significant differencesbetween fungal treatments (including control) for both the percentageof mycorrhization and growth of seedlings. The artificiallyintroduced fungi were not efficient in mycorrhizal formation– naturally occurring fungi were common in all treatments.However, a significant interaction between substrate and fungustreatments in root dry weight was detected. Hebeloma-inoculatedseedlings grown in peat showed the highest value of root dryweight. This fact indicates other possible effects of the fungion root growth independent of mycorrhization. Growth parameterswere negatively correlated with the extent of mycorrhization,indicating allocation of host photosynthates to the fungi. Tothe best of our knowledge, operational inoculation of Norwayspruce seedlings with the test fungi has not been reported previously.