تعیین برخی خواص فیزیکی سه رقم شلتوک در رطوبت های مختلف

Physical properties of agricultural crops are important to design of milling, planting and harvesting machines and also for reducing losses and safe quality of crops along to post harvest stage. In this study, some physical properties of three common varieties paddy rice (i. e. Khazar, Hashemy and Hybrid) including of main dimensions, geometric diameter, mathematical diameter, sphericity, area volume. weight of thousand grains, bulk density, true density, true volume, true density, angle of repose and external friction angle were determined at four level of moisture content( 10, 14, 18, 22% w. b.). Then effect of grain moisture content was investigated on them. Results showed that with increasing of moisture content of grain, main dimensions, geometric diameter, mathematical diameter, sphericity, area, volume, weight of thousand grains, bulk density and angle of repose were increased significantly (p<1%) While true volume was decreased. Also external friction angle was decreased respect to increasing moisture content of grain. At all grain moisture content levels and contact surfaces, the most external friction angle allocated to black sheet. The lowest external friction angle at Khazar and Hybrid allocated to mild contact surface. Also the lowest of this factor at Hashemy variety, obtained for galvanized contact sheet.