Impact of introduced Pseudomonas fluorescens mutants on indigenous rhizosphere microflora of bean

Mutants of Pseudomonas fluorescens were used for inoculation of bean (Phase olus vulgaris L.) at different growth stages to assess their impact on indi genous culturable heterotrophic bacteria in the rhizosphere. Survival of in oculants, changes in numbers of the indigenous bacteria and their physiolog ical state, and microbial community structures were determined using a simp le agar plating method. The results showed that survival of introduced P. f luorescens mutants varied according to the growth stage of bean inoculated. However, overall, the mutants survived better in the rhizosphere with time , when they were inoculated on seeds. In contrast to some authors, the effe ct of mutants introduced was observed in the case of indigenous bacterial n umbers and microbial community structures. Overall, no significant treatmen t effect was observed, when changes in values of kinetic parameters of colo ny formation were considered. Generally, cfu numbers, physiological state a nd community structure of indigenous microflora in the rhizosphere were dep ended on the effect of the interaction between the inoculants, the time aft er the introduction and the growth stage of plant.