Legumes are the next most important sources of food after cereals in Iran. In addition, legumes’ protein content being about 18 to 32 percent makes them have an important role in supplying protein containing food materials to humans. In order to investigate the effect of plant density on yield and its components for two cultivars of common bean in irrigated conditions, an experiment was carried out on the research farm, faculty of agriculture Urmia University during 2002. This research was performed in the form of a split plot factorial design in a randomized complete block, with three replications. Main plots were devoted a three row spacing (30, 45 and 60 cm) while minor plots assigned to three inter row spacing (5, 10 and 15 cm) as well as two cultivars (Derakhshan and Naz) with different growing types. Results obtained from data variance analysis showed that the effects of inter row spacing as well as row spacing on yield within a probability level of 1% is significant. Yield increased with row and inters row spacing decreased. Row spacing and inter row spacing did not have any significant effect on seed per pod. The vegetative traits of the number of sub branches and plant dry matter increased with increase in row and inter row spacing, namely with decrease in plant density. Effect of inter row and row spacing on the first pod was significant. By increase in row and inter row spacing, the first pod was formed at a higher height.
)