Determination of mechanical properties of some commercial sugar beet varieties (DOROTEA, 7112, IC, BR1).

Mechanical properties are important factors for transferring and slicing sugar beet in industry. This experiment was conducted to determine of mechanical properties of some commercial sugar beet varieties (Dorotea, 7112, IC, BR1) in Sugar Beet Seed Institute (S.B.S.I.) of Iran in years 2002-2004. Four varieties, called Dorotea, 7112, IC, BR1, were used and the seeds were planted in early spring, then from each one at harvest time 30 samples were taken. Each sample was included of 50 roots which were separately washed and after defoliation divided into three groups by weight as: small (smaller than 500 gram), medium (500-1000 gram) and large (larger than 1000 gram). Then 13 samples were randomly taken from each group and Shear stress and compression were measured in all three parts (crown, root and tail) by INSTON instrument. In order to do so each part was sliced by knife and six cubic shapes were made which had 2*2.5*2.7 centimeter dimension. Three cubic from six cubic were used for measuring shear stress and three other ones were used for measuring compression. Results showed that average of small, medium and large size in varieties were IC 47, 37,16 percent , BR1 49, 39, 12 percent , 7112 55, 34 11 , Dorotea 32, 43, 25 percent. An oppositive relation was observed between root size and shear stress (R 2 =0.52), also between root size and sugar content (R 2 =0.236), but other parameters including sodium, potassium, Alpha-amine were increased. Module of elasticity increased up to 800-850 gr. and then decreased (R 2 =0.16). The results show shear stress in varieties as Dorotea7112BR1IC, and in crown was larger than tail and tail larger than root. As a matter of fact decreasing in shear stress and increasing in module of elasticity results in improving slicing and transferring processes in sugar beettherefore considering shear stress and compression as important factors in sugar beet seed breeding are recommended.