Studies on Phosphate-Solubilizing Bacteria in Soil and Rhizosphere of Different Plants

Three different types of the most efficient phosphate-dissolvers were separately used for inoculating either wheat grains or broad-bean seeds. The selected micro-organisms were: aerobic spore-forming bacilli, non-sporeforming micrococci, and mycelial formers (actinomycetes). Both sterile and non-sterile soils as well as control pots (without seed inoculation) were used for growing the two plants (for 40 days) to find the effect of inoculation on plant growth, phosphorus percentage in the plants and uptake of phosphorus. Inoculated wheat grains and broad-bean seeds with the different types of phosphate-dissolvers resulted in increased uptake of phosphorus as well as in phosphorus content of the plants, grown either under sterile or non-sterile conditions. Generally, however, both plants contained greater quantities of phosphorus when grown in the presence of normal soil microflora (non-sterilized soil) than in their absence. This may demonstrate the influence of natural microbial flora on the availability of phosphorus to the growing plants. The results also suggest that the individual phosphate-dissolvers are not equally effective when inoculated on different plants. The mycelial-formers were significantly superior to the other two micro-organisms with respect to their effect on P-uptake by wheat grown in sterile soil. In non-sterile soil, the aerobic sporeformer inoculant was superior in case of wheat and inferior to the other two organisms in case of broad-bean.

Weizen- und Pferdebohnensaatgut wurde mit einzelnen Gruppen phosphatlösender Mikroben (aerobe Bazillen, Mikrokokken und Aktinomyzeten) beimpft und in sterilen oder nicht sterilen Boden ausgesät. In allen Fällen haben die beimpften Pflanzen mehr Phosphor aufgenommen als die Kontrollpflanzen. Aber auch die natürliche Bodenmikroflora erhöhte die Phosphoraufnahme im Vergleich zur sterilen Kontrolle. Einzelne Mikrobengruppen waren unterschiedlich wirksam in Abhängigkeit von der Bodenmikroflora und der Art der Pflanze.