In order to evaluate the effects of irrigation withholding and harvest times on yield and quality of sugar beet, field experiments were conducted in 2004 and 2005. The experiment was consisted of four harvest times (155, 170, 185 & 200 days after emergence) and four irrigation withholding dates (10, 20 30 & 40 days before harvest). Different harvest times and irrigation withholding dates significantly affected the root and sugar yield. Root and sugar yield and sugar content were increased significantly with the delay of harvest time. Increase in length of irrigation cutoff date from 10 to 40 days before harvest reduced root yield but increased total and white sugar content. The highest sugar and white sugar yield in our study were achieved at the last harvest time (200 days after emergence) and irrigation cutoff date of 10 days before harvest, that had no significant difference with irrigation cutoff dates of 20, 30 and 40 days before the last harvest time. Producing near equivalent amounts of sugar with less irrigation (irrigation cutoff date of 40 days before harvest) can increase the efficiency of sugar beet irrigation. Reduction of sugar beet irrigation during late growth season could decrease irrigation amounts and it is important for areas with water deficit in harvest period.
