The use of eucalyptus essential oil for mycorrhizal induction in native tree species

Abstract

The slow development of native tropical tree species may be related to their difficulty in establishing ectomycorrhizal associations in natural conditions. We aimed to evaluate the influence of the eucalyptus essential oil on the growth and on the induction of ectomycorrhiza formation in “bracatinga” (Mimosa scabrella Benth.) and “grápia” (Apuleia leiocarpa (Vogel) J.F.Macbr.). The ectomycorrhizal isolate used was Pisolithus microcarpus. Under laboratory conditions, plants were individually subjected to a completely randomized experimental design with four treatments (plant only (control), essential oil, inoculum only, and inoculum + essential oil). We evaluated plant height, shoot and root fresh weight, number of leaves, shoot dry weight, length of the main root, presence of fungal structures, percentage of root colonization, and the effective contribution of treatments for shoot dry weight production. The addition of both the essential oil and P. microcarpus did not induce the formation of typical ectomycorrhizal structures in bracatinga seedlings. The use of the eucalyptus essential oil alone may contribute to the establishment of the association with P. microcarpus in roots of grápia seedlings. The presence of P. microcarpus increased the height of both bracatinga and grápia seedlings grown in vitro, as well as the shoot dry weight of the former.