Fungos micorrízicos arbusculares nativos na produção de mudas de espécies arbóreas nativas em rejeito da mineração de ferro

Abstract

Inoculation with arbuscular mycorrhizal fungi (AMF) can assist plants growth in nurseries and later establishment of tree species in areas affected by tailings deposition, in addition help improve physical quality such as structuring and stabilizing aggregation in the soil. In order to verify the effect of inoculation of native AMF in the degraded area by the rupture of the Fundão Dam, in Mariana-MG, the inoculation of two different AMF inoculants in the growth of 17 tropical tree species, with potential for use in ecological restoration was evaluated. The sources of AMF propagules used were evaluated in an inoculum potential test. Among the inoculum relationships, the one previously multiplied in trap cultivation was more efficient. This study with AMF was a pioneer for native trees Cybistax antisyphilitica, Gallesia integrifolia and Triplaris americana. In the nursery, inoculation with AMF contributed to the development of Peltophorum dubium and Senna multijuga and to a lesser extent in the species Cedrela fissilis and Cybistax antisiphilitica. Approximately 80% of the tree species studied increased mycorrhizal colonization in the roots with AMF inoculation in nursery sowing. Subsequently, experiments were carried out in a greenhouse to assess the effect of AMF inoculation previously carried out in a nursery and inoculation with native AMF at the time of planting in pot with the iron mining tailings technosol as a substrate. There were three tree species: Peltophorum dubium, Cedrella fissilis and Triplaris americana. For each species, an independent experiment was installed, and the treatments were inoculation (IA) or not (NI) with AMF in nursery and inoculation (I) or not in pot (N), thus constituting a 2x2 factorial, with five replications. A control maintained without a plant was also implemented. Growth variables were accessed: height, stem diameter, root dry matter, shoot dry matter; and variables linked to mycorrhizal fungi such as mycorrhizal colonization, extraradicular mycelium length and spore density. In experiment with P. dubium, soil protein related to glomalin was quantified. In the three experiments, the following physical properties in the soil were evaluated: soil density, total porosity, macroporosity, microporosity, blocked pore volume and resistance to penetration. In the experiment with P. dubium, the stability of aggregates in the soil was also evaluated. The inoculation with the mycorrhizal fungi found in the degraded area did not significantly alter the development of the plants and all species developed well on technosol. Physical variables pointed to a benefit from inoculation with AMF, highlighting positive effects on aggregate stability in the experiment with P. dubium and resistance to penetration in all experiments, which informed the beginning of formation and stable structures in soil. As a way to accelerate the recovery of this new edaphic environment formed after tailings dam burst and for other similar materials from iron mining, mycorrhizal inoculation tends to favor the structuring of the material, improving physical conditions for plants and others soil organisms.