COMPETITION BETWEEN TUBER-MELANOSPORUM AND OTHER ECTOMYCORRHIZAL FUNGI UNDER 2 IRRIGATION REGIMES .1. COMPETITION WITH TUBER BRUMALE

A glasshouse experiment was conducted to simulate the competition betw een artificially introduced Tuber melanosporum (Vitt.) and other symbi onts, occurring on outplanted truffle-producing trees. Hazel (Corylus avellana L.) seedlings, previously inoculated with Tuber melanosporum, were rapidly infected with the competing truffle Tuber brumale (Vitt. ), added to the soil as spores. Coexistence of both species on the roo t system was observed. Tuber melanosporum survived and continued to sp read. Tuber brumale, which is naturally present in many truffle-orchar d soils, protects the roots from other ectomycorrhizal symbionts. Alth ough high water content is unfavourable for the development of T. mela nosporum in the absence of other Tuber species, Tuber brumale stimulat es the development of T. melanosporum under these conditions.