Effect of phosphate solubilizing analogue resistant mutants of Azotobacterchroococcum on sorghum

A study was conducted during rainy season (kharif) in 1995 on sorghum (Sorg hum bicolor (L.) Moench) with phosphate solubilizing Azotobacter chroococcu m to observe an interactive effect. Phosphate solubilising analogue resista nt mutants of Azotobacter chroococcum PS 2, PS 6 and PS 11 showed a positiv e interactive effect on 'HC 171' sorghum. Different growth parameters like plant height, number of plants/m row length, green and dry fodder yield inc reased significantly by inoculation of different bacterial strains. Three l evels of fertilizers were applied control (FL0), 90 kg N+13 kg P/ha (FL1) a nd 90 kg N + 26 kg P/ha (FL2). Without inoculation of sorghum seeds with ba cteria and fertilizer level FL2 showed increased yield over control and FL1 with application of P solubilizing A. chroococcum strains there was no sig nificant difference on growth parameters at FL1 and FL2 fertility levels in dicating that inoculation of P-solubilizing Azotobacter strains can reduce fertilizer levels from 26 kg P/ha to 13 kg P/ha.