Studies of microbial development on mycorrhizosphere and rhizosphere soils of potted maize plants and the inhibitory effect of rhizobacteria isolates on two fungi

Extracts from maize rhizosphere and mycorrhizosphere soil (both sterilized and unsterilized) were studied to assess the compatibility of the arbuscular mycorrhizae (AM) fungus (Glomus mosseae) with certain soil fungi, bacteria and rhizobacteria followed by assessment of the inhibitory effect of the identified rhizobacteria on growth in culture of some selected fungi. The treatments were "non sterile soil without mycorrhizal inoculation (S super(-)M super(-)), non sterile soil with mycorrhizal inoculation (S super(-)M+), sterile soil without mycorrhizal inoculation (S+M super(-)) and sterile soil with mycorrhizal inoculation (S+M+)". The five rhizobacteria species isolated from the rhizosphere and mycorhizosphere of both sterile and non-sterile soil were Rhizobium leguminsorum from S+M-, Rhizobium japonicum from S+M+, Pseudomonas sp. from S-M+ and Pseudomonas fluorescens and Rhizobium melotti from S-M-. All the three selected rhizobacteria species (Pseudomonas sp., P. fluorescens and R. japonicum) inhibited growth of the target fungi. Both P. fluorescens and R. japonicum had the most favourable sustained inhibitory effect on Aspergillus flavus while P. fluorescens had the best sustained inhibitory effect on Rhizopus oligosporus.