A field experiment was conducted to investigate the impact of beneficial microorganism (BMO) and phosphorus (P) application on dry matter (DM) accumulation and partitioning in spring wheat (Triticum aestivum L., cv. Siren) under full irrigated (no moisture stress) and limited irrigated (dryland or moisture stress) conditions. The experiment was conducted at the Agronomy Research Farm, The University of Agriculture Peshawar during winter 2012-13. The experiment under both moisture conditions was laid out in randomized complete block design using three replications. The results revealed that DM accumulation and partitioning into leaf, stem and spike was significantly higher in wheat under irrigated than dryland wheat. The treated plots (rest) had higher total DM accumulation and partitioned more DM into leaf, stem and spike than control at both anthesis and physiological maturity (PM). Application of P and BMO at the highest rates (90 kg P ha-1 and 30 L ha-1, respectively) had accumulated more total DM and had partitioned more DM into leaf, stem and spike at the two growth stages. We found that under irrigated condition, increase in both P and BMO levels (90 kg P ha-1 and 30 L ha-1, respectively) and under dryland condition the intermediate levels of both P and BMO (60 kg P ha-1 and 20 L ha-1, respectively) had produced higher total DM and partitioned more DM into various parts at both anthesis and PM. The percent DM partitioning into leaf was more (36%) than stem and spike (each 32%) at anthesis stage; while at PM, more DM was partitioned into spike (59%) than stem (21%) and leaf (20%). Increase in DM partitioning into spike under both irrigated and dryland wheat with proper P and BMO management showed a positive relationship with grain yield that resulted in higher growers income in the study area.