Growth promotion mediated by endophytic fungi in cloned seedlings of Eucalyptus grandis x Eucalyptus urophylla hybrids

Eucalyptus cultivation has expanded considerably in Brazilian systems, leading to the current search for technologies to optimize growing conditions and the production of seedlings in nurseries. Based on the understanding that the development of tree species such as Eucalyptus sp. can be influenced by endophytic fungi that act directly as plant growth-promoting species, cloned seedlings of Eucalyptus grandis x Eucalyptus urophylla hybrids grown from minicuttings we stimulated with three species of endophytic fungi and the effects of inoculation on seedling growth was evaluated. Strains of Trichoderma sp., Fusarium sp. and Papulaspora sp. were forced to colonize the root system of the plants, which were continuously maintained under protected cultivation. Inoculation of the symbionts had positive effects on stem length, stem diameter and the fresh and dry biomass of the treated plants. Non-inoculated plants presented a shorter stem length than the plants treated with any of the endophytic species. The cloned seedlings inoculated with Trichoderma sp. exhibited the greatest stem measurements at 120 days after transplanting. The seedlings inoculated with Fusarium sp. displayed a greater number of leaves than the other seedlings as well as greater amounts of fresh and dry biomass. The authors also conducted quarterly evaluations of the increment in seedling growth promoted by the inoculants, which were more effective in the early stages, up to 60 days after transplanting.