Abstract
The investigation was aimed to determine the effect of inoculation of two different strains of phosphate solubilizing microorganisms (PSM I, strain CA 18 and PSM II, strain 54RB), plant growth promoting rhizobacteria (Enterobacter strain A) and Rhizobium (strain Tal 377) on yield, number and weight of nodules of soybean plant. The experiment was conducted under natural condition. Soybean seeds were coated with carrier-based inoculum of Rhizobium (strain Tal 377) prior to sowing while PSM I (strain CA 18), PSM II (strain 54RB) and Enterobacter were applied as broth culture to seedlings at two-leaf stage. The numbers of nodules were counted at flowering stage and the diameter of pink bacteroid tissue was measured. Both the strains of PSM were tested for their efficiency to solubilize the tricalcium phosphate in vitro. Colony diameter, halozone production and solubilization index of PSM II (strain 54RB) was greater than that of PSM I (strain CA 18). Beneficial effects of inoculation with Rhizobium (strain Tal 377), Enterobacter (strain A) and PSM I and II were obtained in all growth parameters on soybean. Co-inoculation with the above mentioned microbes resulted in maximum increase in plant biomass, root nodulation, number, weight and length of pods as compared to control (non-inoculated) and single. The coinoculation of PSM strain and Enterobacter was most effective and may be exploited in the production of biofertilizer.