Effect of Plant Species and Mycorrhizal Inoculation over Soil Phosphate-Solubilizing Microorganisms in Semi-arid Brazil

Lília C. Carvalhais, Patrícia P. Pinto, Sandra R. Matias, Eduardo J. Corrêa, Neimar Freitas, Maria Aparecida Sugai, Raul V. Passos, Nadja Sá, Maria Rita Scotti

Departamento de Botânica/Instituto de Ciências Biológicas /Universidade Federal de Minas Gerais.

Jaíba Project is an irrigation enterprise in the north of Minas Gerais state and its native vegetation is a dry deciduous forest of Caatinga. Two experimental areas (1,5 ha/site) were established in a degraded area using native species intercropped with Eucalyptus camaldulensis in completely randomized three blocks. In each experimental area six plots with forty plants per species were randomly distributed in each of this blocks. In the first area, these six plots were cultivated as follow: 1- Paraptadenia sp., 2- Paraptadenia sp. inoculated with Rhizobia and spores of Arbuscular Mycorrhizal Fungi (AMF), 3- Eucalyptus camaldulensis, 4- Eucalyptus camaldulensis + AMF, 5- Paraptadenia sp. + Eucalyptus camaldulensis + Tabebuia sp., 6- Paraptadenia sp. (inoculation: Rhizobia + AMF) + Eucalyptus camaldulensis (inoculation: AMF) + Tabebuia sp. In the other area plots were cultivated as follow: 1- Schinopsis brasiliensis Engl, 2- Schinopis brasiliensis + AMF, 3- Eucalyptus camaldulensis, 4- Eucalyptus camaldulensis + AMF, 5- Schinopis brasiliensis + Myracrodruon urundeuva Fr. Allen + Eucalyptus camaldulensis, 6 - Schinopis brasiliensis (inoculation: AMF) + Eucalyptus camaldulensis (inoculation: AMF), Myracroduon urundeuva. Soil was sampled in rhizophere of each cultivated plant and analyzed in relation to the number of Phosphate Solubilizing Microorganisms (PSM) and AMF spores. The results showed that number of PSM and AMF were significantly higher in inoculated Eucalyptus rhizosphere, when compared to the other treatments and specially non-inoculated Eucalyptus plants rhizosphere. We can conclude that Eucalyptus plant demand large amounts of phosphorus and mycorrhizal fungi may improve phosphate absorption. On the other hand, Mycorrhizal Fungi, which were colonizing the Eucalyptus roots, favored the increase of the PSM population. Non-inoculated Eucalyptus plants did not have significant effect over PSM population.

Supported by Ministério do Meio Ambiente/ Fundo Nacional do Meio Ambiente