Two field experiments during the winter seasons 2012/2013 and 2013/2014 were conducted at the North Nile Delta region Sakha Agricultural Research Station Farm(31¯ 07° N Latitude, 30¯ 57° E longitude) to investigate the water behavior of sugar beet (Beta vulgaris L.) crop under different rates and doses of nitrogen fertilization on yield, some yield attributes, quality and some water relations. A split-split plot design with four replicates was used in the present study, where the main plots were randomly assigned by irrigation treatments which were irrigation at 55, 70 and 85% depletion of available soil moisture (I1,I2 and I3, respectively). While, sub-main plots were also randomly assigned by nitrogen rates which were N1, N2 and N3 (application of 30, 60 and 90 kg N/fed., respectively). Also, sub-sub main plots were randomly assigned by nitrogen doses which were as one, two equal and three equal doses through the growing season D1 , D2 and D3, respectively. The results indicated that the highest values of water applied, consumptive use and water storage were recorded under I1 in the two growing seasons and the values were (2751.0, 2790,4), (2235.5, 2250.2) and 2300.13, 2325.96 m3/ fed. On the contrary, the lowest values of the above-mentioned studied parameters were recorded under I3 and the values were 2259.6, 2293.2 and 1800.0, 1832.1 and 1990.18 and 2045.41 m3/ fed. For water applied, consumptive use and water storage in the first and second seasons, respectively. Concerning with water productively (WP) and productivity of irrigation water (PIW), the highest mean values were recorded under I1 and the mean values were 13.94, 14.01 kg / m3 for WP and11.34, 11.30 kg / m3 for PIW, but the lowest mean values were recorded under I3 and the values were 12.65, 12.55 kg / m3 and 10.08 and 10.03 kg / m3 for WP and PIW in the first and second seasons, respectively.
Regarding water application efficiency, the highest mean values were recorded under I3 and the values are 88.08, 89.19% but the lowest mean values were recorded under I1 and the values are 83.61 and 83.36% in the first and second seasons, respectively. Concerning the effect of nitrogen rates and doses on consumptive use, WP and PIW, the highest mean values were recorded under N3 and D3. Data showed water storage and water application efficiency were slightly affected by both nitrogen rates and doses. Sugar beet root yield, top yield and root diameter were highly significant affected by irrigation treatments, nitrogen rates and doses in the two growing seasons. Where, the mean values for the abovementioned studied parameters were increased with increasing water applied, nitrogen rates and doses. Although root length increased with decreasing amount of irrigation water applied.
Sugar yield, purity, nitrogen concentration in tops and roots increased with increasing irrigation water, nitrogen rates and doses. On the other hand, sucrose percentage increased with decreasing irrigation water and nitrogen rates but increased with nitrogen doses.