COMPARATIVE-STUDIES ON MICROBIAL ACTIVITY IN AZOTOBACTER-CHROOCOCCUM INOCULATED WHEAT (TRITICUM-AESTIVUM) RHIZOSPHERE BY PLATE-COUNT AND MANOMETRIC METHODS

The serial dilution plate count method has been generally used to esti mate the number of microorganisms in the rhizosphere soil. However, th is method gives a partial view of the range of organisms and the micro bial biomass in the soil. In view of finding an alternate method to es timate the microbial activity, in the present study the plate count me thod was compared with the respiratory activity of rhizosphere soil me asured by a manometric technique. Two strains of Azotobacter chroococc um were used for seed inoculation of three varieties of wheat. Periodi cally, the titres of different groups of microorganisms, viz. bacteria , actinomycetes, fungi and Azotobacter were determined by the plate co unt method and the results obtained were correlated with the respirato ry activity of rhizosphere soil.