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 beneficial effects may vary according to the combination of plant species, Frankia and mycorrhizal strains. Efficiency of two different AM strains, Glomus fasciculatum (LFSC) and Glomus mosseae (LMSS), originally obtained from Italian sand dunes, and a Frankia strain, UFI 01010104 (AcI4), alone and in combination, in promoting growth of Alnus cordata seedlings in a steam-sterilized non-fertilized soil mixture (peat moss:lignite 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 colonized alder seedlings. Go-inoculation of Frankia with mycorrhizal strains increased nodule dry weight, significantly with LFSC. Frankia significantly increased mycorrhizal infection by LMSS, while reducing LFSC percent infection; mycorrhizal root length was, however, not affected. No significant differences were observed in the mycorrhizal efficiency of the two fungal strains in promoting plant growth. Mycorrhizal inoculation had the largest effects on root architecture, increasing root length and root branching.