Effect of irrigation cut- off time at the end of growth period on storagability of sugar beet

In most of the sugar beet cultivated areas including Kermanshah, Iran, late season irrigation is cut- off earlier than usual which causes drought stress in the crop. Since root yield still increses in Sept. and Oct. these areas, withholding irrigation in this period reduce root yield and quality of sugar beet. For this reason, an experimente was conducted during 004- 005 based on split plot design with four replications in Kermanshah. Withholding times (, 0, 0 Sept. and 0 Oct) were assigned to the main plot and three on- form silage period (0, 0 and 30 days) to the subplots.Withholding irrigation on 0th Sept had the lowest root yield(4.4 tha-) and that of 0th Oct. had the highest root yield (50.96 tha-) indicating that the later the irrigation cut- off, the higher the root yield is. Silage for 30 days decreased root yield about 8.5 percentage. Sugar content was not greatly affected by irrigation cut- off and silage treatments but sugar yield is an important character in sugar beet production. Because sugar yield was not significantly affected by irrigation treatments, in some water limited aren and irrigation cut- off in 0th or 0th Sept is recommended.