Allelopathic interactions between the oligonitrophyllic microorganisms from the rhizosphere soils of grasses

The population of oligonitrophyllic soil microorganisms were examined during the plant debris degradation in the ecosystem disturbed by harvesting the black locust forest. Investigations were done in:the rhizosphere soils of grasses (Agropyron repens, Festuca spp., Poa sp.) and in the mycorrhizosphere soil of hypogeous fungi Tefezia terfezioides (Matt.) Trappe. Soil samples were collected from the previous black locust forest in Deliblato sands (Serbia). Saprophytic microorganisms (family Mycobacteriaceae) mainly developed among the oligonitrophyllic microbial populations. The maximum population of microorganisms was found during the microbial degradation of frozen mature fungal fruit-bodies. While, the smallest number of microorganisms were recorded in the rhizosphere soil of mixed grasses. Marked differences in the numbers of soil microorganisms indicated the possible allelopathic effects of test grasses on the microorganisms. The nitrogen requirements of different microorganisms were variable. The application of tannic acid and pyrogallol influenced the development of bacteria and actinomycetes in the microbial populations. The applied tannic acid increased the population of moulds but applied pyrogallol completely inhibited their development.