Einfluß der P-Ernährung und der Applikation P-lösender Bakterien auf die funktionelle Diversität der Rhizosphärenmikroflora von Mais

Abstract

The effect of P-fertilizer formulation (without P fertilization, with hardly soluble CaHPO₄ and with easily available NaH₂PO₄) on the microbial community structure in the rhizosphere and its activity was investigated in a greenhouse pot experiment with quartz sand. Furthermore, the effect of a P-solubilizing bacterial strain Pantoea agglomerans on the microbial community structure was tested. The community structure and C substrate use activity were measured using Biolog gram negativ and gram positive plates. The results showed an increased microbial activity with increasing P availability in the rhizosphere. Distinctive patterns of C source utilization were apparent for each P-fertilizer formulation. The P-solubilizing bacterial strain improved total C substrate use activity when CaHPO₄ was the only phosphate source. After bacterial inoculation the rhizosphere microbial community structure changed and the substrate use activity of some carboxylic acids was increased. Thus, these changes depend on nutritional conditions and bacterial inoculation which should be taken into account by interpreting bacterial inoculation experiments.