ABSTRACT Physical attributes of two common Iranian varieties of safflower seed (namely Golshid and Afshan), such as geometric properties (size, geometric mean diameter and sphericity), gravimetric properties (thousand seed mass, bulk density, true density and porosity) frictional properties (emptying angle of repose and coefficient of static friction on four structural surfaces) and terminal velocity were determined as a function of size (large, medium, small) and moisture content in the range of 4 to 20% (d.b.). The results showed that the mean values of all geometric properties increased linearly with increasing moisture content. Among the varieties, Afshan had the highest values of geometric properties, in all moisture contents and size studied. At studied moisture contents and size categories, thousand grain mass, true density and porosity increase linearly, but the bulk density of safflower seeds linearly decrease as moisture content increase from 4 to 20 %. Among the applied surfaces, rubber (0.5–0.69) showed the highest value of friction coefficient safflower seed followed by plywood (0.45–0.63), galvanized iron (0.41–0.54) and aluminium (0.36–0.47). The obtained values of emptying angle of repose increase linearly with an increase in moisture content and size categories. The terminal velocity of Golshid variety varied from 6.1 to 6.7, 5.8 to 6.3 and 5.3 to 5.9 m/s for large, medium and small sizes, respectively. The range of terminal velocity for Afshan variety obtained 6.4–7.2, 6.3–6.9 and 6–6.6 m/s, respectively.

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