The aims of this study were to test a new mycorrhizal inoculation process using a "catalyser" of the mycorrhizal establishment (termite mounds of Macrotermes subhyalinus) to minimize the requested volume of fungal inoculum added to the cultural substrate. The effects of the termite mound were explored on mycorrhiza formation between an Australian Acacia, Acacia holosericea and an ectomycorrhizal fungus or an arbuscular mycorrhizal fungus using a two-step cultural system. The first step of this cultural practice was the inoculation of A. holosericea seedlings in small soil volumes (5 L plastic containers planted with 100 pre-germinated seeds) whereas the second one allowed the development of these mycorrhized plants in larger soil volumes (1 L pots planted with one seedling). Termite mound amendment significantly enhanced the mycorrhizal formation from both types of fungal isolates. This stimulating effect could probably be attributed to the introduction via the termite mound of a bacterial group (that is, fluorescent pseudomonads) that could act as Mycorrhiza Helper Bacteria (MHB). Since it is possible to reduce the requested fungal inoculum in controlled mycorrhization practice using M. subhyalinus mound powders, this biotechnological process could be useful in reafforestation of tropical regions by lowering the requested fungal inoculum quantities and reducing the financial costs of controlled mycorrhization in forest nurseries.
Key words: Termitaria, fluorescent pseudomonads, controlled mycorrhization, Acacia holosericea