Isolation of siderophore-producing strains of Rhizobium meliloti and theirbiocontrol potential against Macrophomina phaseolina that causes charcoal rot of groundnut

Of the 12 isolates of root-nodulating bacterium, Rhizobium melitoti isolate d from the medicinal plant, Mucuna pruriens, only two were able to produce siderophores. The two isolates (RMP3 and RMP5) were able to inhibit a widel y occurring plant pathogen, Macrophomina phaseolina that causes charcoal ro t in groundnut. Further, there was a marked enhancement in percentage seed germination, seedling biomass, nodule number and nodule fresh weight of M. phaseolina-infected groundnut plants inoculated with the strains RMP3 and R MP5, compared to uninoculated and uninfected controls. Thus plant growth pr omotory nature of both the rhizobial strains was confirmed.