Influence of green manure from inoculated gliricidia on rhizobacterial population in the rhizosphere of maize

The evolution of bacterial population size in the rhizosphere of maize through amendment with different organic materials from gliricidia plants was investigated. Greenhouse experiments were consecutively conducted for gliricidia biomass production and maize growth in Niayes zone soil. The plate count methods allowed estimation of rhizobacterial abundance in soil sampled from maize root systems. The density of two plant growth promoting rhizobacteria (PGPR) groups, mainly phosphate solubilizing bacteria (PSB) and fluorescent pseudomonads, was markedly affected by organic amendment. A positive rhizospheric effect of cultivated maize was observed on each rhizobacterial population investigated. Application of organic amendment allowed to get the highest PSB and pseudomonad abundance in maize rhizospheric soil which were estimated at log 5.76 and log 6.08 respectively. However, the nature of plant material used as green manure, did not influence neither abundance of PSB nor fluorescent pseudomonads in the rhizosphrere of maize.