Effect of Different Tillage Methods on Root Yield and Yield Components of Sugar Beet (Beta vulgaris)

A two-year field experiment was conducted at the Research Site of Hamedan Agricultural and Natural Resources Research Center, Hamedan, Iran on the loam soils to study the effect of different tillage methods on root yield and yield components of sugar beet (Beta vulgaris) during 2008 and 2009 growing seasons. Tillage treatments in the study were moldboard plow + two passes of disk harrow (MDD) as conventional tillage method; moldboard plow + one pass of rotavator (MR), chisel plow + one pass of rotavator (CR) and two passes of disk harrow (DD) as reduced tillage methods; one pass of rotavator (R) and one pass of tine cultivator (C) as minimum tillage methods, and no-tillage (NT) as direct drilling method. Root yield (RY) and some yield components such as root number per hectare (RNPH), sugar yield (SUGY), root dry matter (RODM), root length (ROTL), rim diameter (RIMD) were determined for all treatments. Different tillage methods significantly (P # 0.05) affected RNPH, but there was no significant difference in other studied traits. Although there was no significant difference in RY, SUGY, RODM, ROTL and RIMD, results of the study showed that tillage practices were beneficial in improving the yield of sugar beet. The maximum values of RY (82.7 t ha-1), RNPH (135412 roots ha-1), SUGY (11.4 t ha-1) and RODM (23.9%) were observed in case of MR treatment, while the maximum values of ROTL (20.5 cm) and RIMD (1.5 cm) were noted in case of NT treatment. In contrast, the minimum values of RY (71.3 t ha-1), RNPH (115000 roots ha-1), SUGY (9.15 t ha-1) and RODM (20.3%) were observed in case of NT treatment, while the minimum values of ROTL (18.0 cm) and RIMD (1.1 cm) were noted in case of MR treatment. Results also showed that tillage method affected the yield of sugar beet in the order of MR > CR > R > MDD > DD > C > NT. Therefore, the reduced tillage treatments MR and CR, and the minimum tillage treatment R were considered as more appropriate and profitable tillage methods in improving the yield of sugar beet.