Seed weight is primary component, and an important contributor to soybean yield. For the purpose of better understanding the effects of defoliation treatments on grain characteristics such as effective filling period, grain filling rate, oil and protein content, an experiment was conducted in the research field of the Islamic Azad University of Kermanshah, Iran at 2010. The experimental design was a split plot in randomized complete block with three replications. Main plot treatments consisted cultivars V1=Williams and V2=Clark, and Subplot included six treatments of defoliation and pod removal: removing none (T1), one lateral leaflet at R1-R3 (T2), two lateral leaflets at R1-R3 (T3), one lateral leaflet at R5-R6 (T4), two lateral leaflets at R5-R6 (T5) and pods removal 50% at R5 +10 days (T6). The results was shown that there is significant differences among cultivars in oil and protein content (P<0.01), and effective filling period (P<0.05). Except of oil content, other traits affected by pods and leaflets removal treatments at 0.01 levels, while Interaction effects (V×T) were not significant on all of evaluated traits. Two lateral leaflets removal at R1-R3 had the lowest grain filling rate, protein content and grain weight per plant and the longest effective filling period. Oil and protein content in Williams higher than the Clark.
