Studies on Dual Mycorrhizas of Eucalyptus globulus and E.urophylla Ⅰ.Fungal Colonization and Interactions

This paper represents the first part of the results from a glasshouse experiment designed to compare the competition of ECM and VAM fungi on root colonization and effects on growth of two Eucalyptus species (E.globulus and E.urophylla).One ECM fungus(Laccaria lateritia) and three VAM fungi belonging to genera Glomus,Acaulospora and Scutellospora,along with field soil as well,were used to inoculate Eucalyptus seedlings alone or in combination.Both ECM and VAM fungi colonized and formed mycorrhizal associations on roots of inoculated seedlings,though infective rates of VAM and ECM tips per meter varied according to inoculant fungi and plant ages. There were some regressive interactions for colonization between the two fungi,as a general trend for ECM root colonization levels to increase with time at the expense of VAM colonization was observed during 16 weeks. The effect of phosphorus levels in soils on mycorrhizal formation was discussed.