Plant growth promoting rhizobacteria (PGPR) were
first defined by Kloepper & Schroth, (1978) as the soil
bacteria that are closely associated with plant roots,
colonize them and enhance plant growth. Associated
microorganisms in soil environment influence plant
diseases. Interaction of one pathogen may also alter the
host response to subsequent infection by another (Taylor,
1979). Infection of roots by soil-borne root infecting fungi
resulting in development of root rot and wilt diseases
(Armstrong et al., 1976) and one fungus predispose crop
plant to infection by other fungi (Dieter & Défago, 2005).
The prospects of manipulating crop rhizosphere microbial
populations by inoculation of beneficial bacteria to
increase plant growth has shown considerable promise in
laboratory and greenhouse studies (Dawar et al., 2008),
but responses have been variable in the field (Bowen &
Rovira,1999)