Two field experiments were carried out during 1997 and 1998 seasons to study the effect of inoculation with Azospirillum lipoferum combined with either the vesicular arbuscular mycorrhiza (VAM) Glomus mosseae or the phosphate solubilizing bacterium (PSB) B. megatherium var phosphaticum on the growth and yield of maize .
The results of this study showed that inoculation with A. lipoferum combined with VAM in the presence of full dose of rock phosphate gave the highest values of C02 evolution and N2-ase activity in rhizosphere soil.
The percentage of mycorrhiza! root infection was higher in rock-p than super-p treatments. Densities of p-dissolving bacteria in rhizosphere were the highest when maize grains were inoculated with PSB and provided with the full dose of super-p. Ammoniacal and nitrate nitrogen contents in the soil were the highest in VAM inoculated treatments which received full dose of rock-p. The highest values of available-p were recorded in PSB inoculated treatment which received full dose of super-p.
The highest records of growth performance of maize plants was observed with VAM combined with Azospirillum lipoferum. Also, dual inoculation with A. lipoferum combined with VAM in the presence of full dose of rock phosphate gave the highest values of yield and yield components of maize compared with dual inoculation with A. lipoferum combined with PSB.
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