effects of nitrogen fertilizer and deficit irrigation on quantitative and qualitative traits of sugar beet

water scarcity in arid and semi-arid climate of iran has made deficit irrigation as a strategy for optimal water use and conservation in agricultural sector. this study aimed at evaluating the effects of water-deficit stress and n fertilizer levels on sugar beet performance. the study was conducted in split block design based on randomized complete block design arrangement. the row factor consisted of normal irrigation (ni), three partial root drying levels including 85% (prd85), 75% (prd75) and 65% (prd65) and regulated deficit irrigation including 85% (rdi85), 75% (rdi75) and 65% of the crop water requirement (rdi65) and column factor consisted of two n fertilizer levels including 100% (f100) and 75% of fertilizer requirement (f75). the amount of irrigation water in ni treatment was 976 mm. results showed significant differences among irrigation treatments for all traits. nitrogen fertilizer treatments had significant effect on root yield, sugar content, and white sugar yield. the highest root yield (47.7 t.ha-1) and white sugar yield (6.8 t.ha-1) were observed in ci treatment. however, no significant difference was found between ci and prd85 treatments. the lowest root yield (26.1 t.ha-1) and white sugar yield (3.9 t.ha-1) was observed in rdi65 treatment. the f100 treatment had higher root yield (39.5 t.ha-1) and white sugar yield (5.8 t.ha-1) compared with f75 with 37.1 t.ha-1 root yield and 5.6 t.ha-1 white sugar yield.