A field experiment was carried out at Shandaweel Agricultural Research Station, Sohag, Egypt to study the effects of deficit irrigation and harvesting dates on yield and water productivity of three sugar beet varieties. A split split block design with three replications was used. Main blokes were assigned to three irrigation water regimes (100%, 85%, and 70% of water requirement). The sub blots were occupied by three harvesting dates (180, 195 and 210 days). Sub- sub plots were comprised three sugar beet varieties namely (RAVEL, SV1841and SA1686).
Results indicated that reducing water supply reduced roots, sugar and biomass yields but increased water use efficiency (WUE). Increasing harvesting date increased roots and sugar yields but reduced biomass yield. Roots, sugar and biomass yields of RAVEL and SA1686 varieties were almost comparable but higher than those of SV1841 variety. The highest sugar WUE was obtained from SA1686 at 70% WR treatment under 210 days harvesting date followed by RAVEL variety at 70 % WR and 210 day harvesting date. Results clarified that cultivating either RAVEL or SA1686 variety with 70% of water requirement and for 210 growing days under Upper Egypt conditions optimized roots and sugar yields and WUE of sugar beets.