SYNTHESIS OF 2 TYPES OF ASSOCIATION BETWEEN MORCHELLA-ESCULENTA AND PICEA-ABIES UNDER CONTROLLED CULTURE CONDITIONS

Morels can grow as saprophytes, but in association with trees, they form sclerotia around mature roots and ectomycorrhizas with rootlets. A Petri dish culture system was used to test the influence of nutritive, physical and biological factors on the association between Morchella esculenta and Picea abies. Reduced levels of nitrogen and phosphorus, active carbon, CaCO3, pH and temperature did not appear to be primary releasing factors for the establishment of any kind of association. A precultivation of the morel mycelium on an extremely poor medium promoted formation of sclerotia around mature roots of the spruce. This sclerotia formation was enhanced when the inoculated plantlets were already mycorrhized with Laccaria amethystina. Furthermore, a premycorrhizal stage could also be obtained when the morel mycelium was precultivated on a special medium stimulating the development of a bacterium which be isolated from morel ascospores and apparently helps the fungus for mycorrhization.