Levantamento quantitativo de microrganismos solubilizadores de fosfatos na rizosfera de gramíneas e leguminosas forrageiras na Amazônia

Abstract

After choosing a selective enrichment medium suitable for most phosphate solubilizing microorganisms, a quantitative survey of these was made in the rhizosphere of: Brachiaria decumbens, B. humidicola. Andropogon gayanus, Paspalum plicatum, Hyparrhenia rufa, Panicum maximum, Desmodium ovalifolium, Pueraria phaseoloides, Zornia sp., Stylosanthes capitata, S. guianensis (CIAT 136). and S. guianensis (IKE 1022, with and without fertilisers. The largest numbers of phosphate solubilizing bacteria (above 1 x 107/g rhizosphere) occurred in the rhizosphere of the leguminous species a nd small numbers (Belw 1 x 107/g rhizosphere) in grasses without fertilisers, except H. rufa and P. maximum. From all the fodder plants analysed, Zornia sp. (Leguminosae) with fertilizer, had the greatest number as phosphate solubilizers. The total number of microorganisms was greater in the treatments without fertilizer in all grasses analysed; but for the leguminous species it was greater for treatments with fertilizer except in S. capitata. Phosphore solubilizing fungi were not considered in this study because they present only in small numbers.