EFFECT OF WATER APPLICATION LEVELS AND DIFFERENT WETTING DEPTHS ON SUGARBEET YIELD AND ITS WATER RELATIONS AT NORTH DELTA

Two field experiments were conducted at Sakha Agriculture Research Station Farm, during 1997/98 and 1998/99 seasons to study the effect of water applied levels (watering at field capacity, field capacity + 5% and field capacity – 5%) and different wetting depths (30, 45 and 60 cm) onsugarbeet yield and its water relations.
The results showed that treatment W1, (field capacity) achieved the highest values of sugarbeet yield (20.17 ton/fed.) followed by treatment W3 (field capacity – 5%) , while treatment W2 (field capacity +5%) recorded the lowest values (18.52 ton/fed. The data indicated that treatment D1 (soil moisture depth of  (30 cm) produced the highest values of sugarbeet yield and weight of the root per plant. The highest sugar yield was scored from soil moisture depth of 30 cm (D1) in the 1st and 2nd seasons (3419.55 and 3791.49 kg/fed.), respectively followed by treatment (D2). The lowest value of sugar yield was obtained from treatment (D3). Treatment W3 (field capacity plus 5%) recorded the highest values of water consumptive use (2479.4 and 2563.34 m3/fed.) followed by treatment W1 (2400.86 and 2484.87 m3/fed.) for the 1^st and 2^nd seasons, respectively. The highest values of water applied was recorded with the irrigation levels at field capacity + 5% and soil moisture depth of 60 cm. The lowest values were recorded by irrigation at field capacity – 5% and to soil moisture depth of 30 cm.  Irrigation at field capacity – 5% (W3) treatment produced the highest values of water use efficiency for sugarbeet and sugar yield in the 1^st and 2^nd seasons, followed by treatment (W1) that irrigated at field capacity. Irrigation at field capacity  + 5% treatment (W2) recorded the lowest values of water use efficiency.
Irrigation at 30 cm of soil moisture depth (D1) achieved the highest values of water use efficiency for both sugarbeet and sugar yield followed by treatment D2 irrigated at depth of 45 cm. While the lowest values were obtained from treatment D3 (irrigated at depth of 60 cm).
Data of soil moisture extraction reveal that most of the moisture was removed from the upper soil surface layer depth. There was a substantial reduction in moisture extraction downward throughout the soil profile.
Generally about 70% of the available soil moisture was extracted by roots from the first foot (0-30 cm), and the rest (30 %) from the second down foot of soil profile.