A b s t r a c t. The effect of irrigation and nutrient treatments on physical properties of safflower seeds was investigated. Physical properties of safflower seeds were determined at a moisture content of 7% w.b. The parameters determined at different treatments were: size, geometric mean diameter, sphericity, surface area, mass, volume, bulk and true densities, porosity, and static and dynamic coefficient of friction. The results showed a better effect of the use of organic fertilizers in comparison with chemical ones. The results showed that nutrient and irrigation treatments had a significant effect on most of the physical properties of safflower seeds at p<0.01.K e y w o r d s: safflower seeds, physical properties, irrigation, nutrient INTRODUCTION Safflower (Carthamus tinctorius L.) oil has been produced commercially and for export for about 50 years, first as an oil source for the paint industry, now for its edible oil for cooking, margarine, and salad oil (Dajue and Mündel, 1996). Safflower has become an increasingly important crop in Iran and worldwide due to the rich nutritional value of its edible oil. It is a rich source of oil (35-40%) and linoleic acid content (75-86%). Currently, the estimated world production is about 636 000 t of safflower seed from an area of 772 700 ha land (FAO, 2010).The estimated Iran production is about 470 t of safflower seed over an area of 740 ha (FAO, 2010). Although Iran does not have a dominating share in the world production of safflower seed, areas under safflower seed cultivation have recently increased because oilseed crops are in extensive demand in Iran to meet the lack of country oil and biodiesel production. In dry land cropping systems, water is the most important limiting factor for crop production. One of the keys to irrigated crop production is correct crop choice to achieve a stable quality under drought stress.There are many investigations on physical properties of different types of oil seeds, such as sunflower (Gupta et al., 2007); hazelnut (Kibar and Ozturk, 2009) and jatropha (Karaj and Muller, 2010). Safflower is an important oilseed crop particularly in arid and semi-arid regions of the world due to its cold, drought, and salinity tolerance (Weiss, 2000). The quantity and quality of crops, especially oilseeds, is influenced by soil fertility and nutrients. Synchronization of plant requirement with the nutrient supply is a problem, especially if the nutrient is supplied from a source whose cycle requires microorganism intermediation (Abbott and Murphy, 2007). With the advent of the Green Revolution, consumption of chemical fertilizers rose rapidly. Statistics shows that the annual consumption of nitrogen and phosphorus fertilizers is 85 and 15 mln t worldwide, respectively (Roy et al., 2006). However, replacement of chemical fertilizers with organic and biological fertilizers plays an important role in environment health (Chandrasekar, 2005). According to the problems that emerged due to indiscriminate use of chemical fertilizers, the use of biolo...