A split plot experiment was conducted to determine the effects of the harvest time on yield and yield components of four sugar beet genotypes (Rasoul, Shirin, Dorothea & BR1). Sugar beet was harvested at five different times (123, 139, 155, 171 & 187 days after emergence). Results showed no significant difference between sugar beet genotypes for studied traits. Leaf area index was affected by year, which was greater in 2003 than 2004 at all harvest times, probably due to more favorable conditions in 2003. Total sugar and white sugar content were increased at all harvests. Late harvesting (187 days after emergence) resulted in greater yield of root, total and white sugar yield than earlier harvesting. The highest white sugar yield was obtained at the last harvest of the sugar beet when rainfall and low temperature did not occur.
