Abstract: Phosphorus is a major nutrient and its deficiency limits plant growth of pumpkin (Cucurbita pepo L.). The investigation was aimed at studying integrated application of phosphorus on growth and production of pumpkin. Co-inoculation of phosphate solubilizing microorganisms (PSM) (mycorrhiza and bacteria) with and without seed inoculations, and P chemical fertilizer at 0, 25, 50, 75 and 100% of recommended fertilizer were applied in a factorial experiment in randomized complete block design with three replications. Data indicate that PSM and P fertilizer show significant effects on all traits. Maximum oil yield (41.80 g m^-2) and linoleic acid (68.30%) were obtained with PSM and 50% of the recommended P fertilizer. Seed yield was significantly increased in response to inoculation of PSM in the presence of low levels of P fertilizer. However, maximum mycorrhizal colonization obtained in 25% recommended P fertilizer. A high level of P fertilizer had a negative effect on the activity of PSM. On the other hand, a low level of phosphorus with PSM has a simulative impact on root colonization and productivity of pumpkin and favoured the activities of PSM.