Abstract: To understand inter-annual variability in grain yield, a pot experiment was conducted to evaluate the effect of sowing date on agronomic, physiologic and yield indicators of wheat. The four sowing dates were October 5 (T1), 10 (T2), 15 (T3) and 20 (T4). Agronomic indicators of the numbers of productive spike and grains per spike, and the 1000-grain weight were measured after wheat harvest. Also physiologic indicators of root activity (RA), acid phosphatase (APA) and nitrate reductase (NRA) activities were measured during wheat growth season. Results indicated that sowing date had significant influence on grain yield and wheat yield was highest for the October 10 (T2) sowing date. Wheat absorptive capacities in nitrogen and phosphorus in T2 treatment were much higher than in other treatments. Productive spikes and grains per spike in T2 were 38.00 tiller·pot 1 and 37.67 grain·spike 1, respectively, also significantly higher than those in other treatments. Productive spikes and grains per spike were positively correlated with wheat yield. While no differences in chlorophyll contents were noted among treatments at tillering stage, it was significantly higher in T2 than in T3 and T4 treatments at jointing and flowering stages. Nitrate reductase activity (NRA) increased with wheat growth in T1 and T2, but remained relatively stable in T3 and T4 treatments during the entire growth period. The activity of nitrate reductase was up to 57.12 g·g^-1(FW)·h^-1 at flowering stage in T2 treatment, significantly higher than those in other treatments. Nitrate content decreased with increasing wheat growth in the treatments. It was highest in T2 at jointing stages, and no significant differences noted among treatments at flowering stage. Acid phosphatase activity (ARP) was about 0.28 mg·g^-1(FW)·h^-1 in all treatments at tillering and jointing stages. It was up to 0.34 mg·g^-1(FW)·h^-1 in T2 at flowering stage, which was significantly higher than in other treatments. In the study, wheat root activity (RA) decreased with delay in sowing date. Analysis showed significant correlation between grain yield and numbers of productive spikes or gains per spike. Also wheat yield was significantly correlated with APA and NRA at jointing stage, and with aboveground biomass and NRA at the flowering stage. The findings of the study suggested that sowing date influenced wheat yield mainly through changing APA and NRA. Also soil N and P absorption varied with sowing date, which in turn caused variations in wheat yield.