SHORT COMMUNICATION EFFECT OF PHOSPHORUS ON ROOT COLONIZATION AND GROWTH PROMOTION OF MAIZE BY BIOLUMINESCENT MUTANTS OF PHOSPHATE-

Several P-solubilizing microorganisms (PSM), are able to solubilize unavailable soil P and increase the yield of crops (Richardson, 1994). Moreover, some strains of rhizobia are PSM and like other plant growth promoting rhizobacteria (PGPR) they can colonize the roots and increase the yield of non-legume crops (Höflich et al., 1995; Chabot et al., 1996a,b). A major barrier to the successful agro-nomic use of bacterial inocula is the need to estab-lish high population densities of the introduced bacterium in the root environment (Kloepper et al., 1989). The nutrient status of the rhizosphere deter-mines the nature of the root exudates and it can have a direct eect on the composition of the rhizo-sphere microbial community (Curl and Truelove