INOCULATION OF ALNUS-CORDATA WITH SELECTED MICROSYMBIONTS - EFFECTS OF FRANKIA AND GLOMUS SPP ON SEEDLING GROWTH AND DEVELOPMENT

Positive effects of dual inoculation with arbuscular mycorrhizal (AM) fungi and Frankia on Alnus cordata Loisel. are reported. Such benefici al effects may vary according to the combination of plant species, Fra nkia and mycorrhizal strains. Efficiency of two different AM strains, Glomus fasciculatum (LFSC) and Glomus mosseae (LMSS), originally obtai ned from Italian sand dunes, and a Frankia strain, UFI 01010104 (AcI4) , alone and in combination, in promoting growth of Alnus cordata seedl ings in a steam-sterilized non-fertilized soil mixture (peat moss:lign ite mine spoil, 1:1; pH 5) was evaluated. The seedlings were grown in a greenhouse under natural day-length and light intensity, and watered as needed. After five months of growth, both fungal strains tested co lonized alder seedlings. Go-inoculation of Frankia with mycorrhizal st rains increased nodule dry weight, significantly with LFSC. Frankia si gnificantly increased mycorrhizal infection by LMSS, while reducing LF SC percent infection; mycorrhizal root length was, however, not affect ed. No significant differences were observed in the mycorrhizal effici ency of the two fungal strains in promoting plant growth. Mycorrhizal inoculation had the largest effects on root architecture, increasing r oot length and root branching.