DISTRIBUTION OF ANTAGONISTIC STREPTOMYCES-GRISEOVIRIDIS IN RHIZOSPHERE AND NON-RHIZOSPHERE SAND

The ability of Streptomyces griseoviridis to colonize roots was studie d on turnip rape (Brassica mpa ssp. oleifera) and carrot (Daucus carot a) using the sand-tube method. The biofungicide Mycostop or a spore su spension of S. griseoviridis was mixed in sterile and in non-sterile s and. Population densities of the antagonist in the rhizosphere were si gnificantly higher than in non-rhizosphere and in root-free sand. Ther e was no significant difference between the plant species and root dep ths on distrubution of the antagonist. Higher rates of detection were achieved when root segments were placed on petri plates of agar than w hen homogenized and subsequently dilution plated. Homogenization of sa nd samples increased the detected population densities of S. griseovir idis. Muramic acid assay with HPLC indicated higher densities in the r hizosphere compared with non-rhizosphere and root-free sand. Distribut ion of S. griseoviridis in the rhizosphere was observed using scanning electron microscopy. The antagonist produced high spore densities in the root-hair zone of turnip rape. S. griseoviridis mixed in sterile a nd non-sterile sand survives in the rhizosphere, non-rhizosphere and r oot-free sand where it probably exists both as spores and mycelia.