Rizosferas de árvores acumuladoras de fósforo na Amazonia Brasileira

Abstract

Rhizosphere of tress that accumulate phosphorus in the Brazilian Amazon. Objective. With the purpose of knowing the strategiesof tolerance of two phosphorus-accumulating species (Neea macrophylla and Cecropia palmate) and a non-accumulating species(Casearia arborea) to phosphorus-deficient soils, we characterized the rhizosphere of these species using a multivariate analysis andcorrelation matrices in relation to the concentrations of organic phosphorus, available phosphorus, soil organic carbon, organic carbonfrom microbial biomass, acid phosphatase enzyme activity, and root infection by mycorrhizal fungi. Materials and methods. Theresearch was carried out in the Igarapé-Açú town, state of Pará, Brazil in secondary forests with five years of regeneration, where theparameters above mentioned were monitored. Results. Results did not reveal significant differences between the species depending onthe characteristics of the soil next to the rhizospheres, suggesting homogeneous conditions. The enzymatic activity was slightly higherin the species with less potential in accumulating P (Casearia arborea) suggesting that efficiency in P use is not determined by theenzymatic activity. Conclusions. Neea macrophylla presented a slightly higher number of mycorrhizal root infections in comparisonto the other species, indicating that this could be a tolerance strategy in those environments, while in Cecropia palmata and Caseariaarborea it seems that enzymatic activity is the strategy employed.

Keywords

• acid phosphatase
• Brazilian Amazon
• rhizosphere