Mycorrhization of container-grown Norway spruce (Picea abies [L.] Karst.) seedlings with fungal bead inoculum

Roots of seedlings grown in controlled greenhouse conditions typically either lack natural ectomycorrhizal development or they are patchily colonized, especially in container-grown planting stock. The rearing of ectomycorrhizal seedlings may have the potential to improve the field survival and growth of seedlings planted on adverse sites. Advantages of container-grown seedlings compared to bareroot ones on such sites are well known. Artificial mycorrhization of seedlings has been frequently recommended to improve development of ectomycorrhizae on root system. Mycelial inoculum of ectomycorrhizal fungi appears to be the most appropriate method of inoculation. Mycelium entrapped in calcium alginate beads can be used as very effective alternative to vermiculite-peat formulation. In this study, bead inocula of Amanita rubescens, Hebeloma crustuliniforme, Laccaria laccata and Paxillus involutus were introduced artificially into polyethylene containers (500 cm3) filled with fumigated peat-perlite substrate (21, v:v) in order to determine their effects on growth and ectomycorrhiza development of one-year-old Picea abies seedlings grown in greenhouse. Beads were placed to containers below developing roots of emerged seedlings handly in band at rate & ml per container. At the end of the first growing season stem height, stem diameter at root collar, root and top dry weights (48 hours at 80 deg C) of seedlings were measured. The root systems were observed at 10-25 x magnification to assess the extent of mycorrhizae expressed as a percentage proportion of number of ectomzcorrhizae from total number of short roots. The data were analyzed by appropriate model of one-way analysis of variance followed by a Tukey's test (p = 0.05) to determine treatment differences. There was no difference in seedling growth and extent of mzcorrhizae between inoculated and uninoculated one-year-old seedlings. Seedlings inoculated with Amanita rubescens showed the highest mean values of growth measurements, the lowest ones those inoculated with Laccaria laccata. Statistically significant growth difference of treatments only in root dry weight variable between these two fungi was found. In general, the extent of mycorrhizae was low, the greatest on seedlings inoculated with A. rubescens again (one third of total number of short roots), the lowest in Hebeloma crustuliniforme treatment (9%). Natural fungal colonization of roots of control seedlings resulted to 20% mycorrhiza extent. The important circumstances that influenced results of experiment were probably growth substrate, application time and rate of inoculum