Two field experiments were carried out during 2003 I 2004 and 2004/2005
growing seasons at Sakha Agric. Res. Station, Kafr EI-Sheikh Governorate to study
yield and quality characters and some water relations of two sugar beet cultivars;
Mezanopoly and Top as affected by three irrigation regime treatments W₁ full
irrigation which received planting plus seven irrigations, W2 withholdihg one
irrigation and W3 withholding two irrigations at late season and three levels of
potassium fertilization 24, 48 and 72 Kg K20 Ifed. It aimed at maximizing sugar beet
production and water use efficiency. The experiments were conducted in split-split
plot design, with four replicates. The observed results can be summarized as
follows: Water consumptive use was the highest with the treatment under full
irrigation regime, where it was 63.99 and 66.92 ern in 2004 and 2005. While it was
the lowest with the W3 treatment, 51.34, and 53.35 ern in 2004 and 2005. The daily
water consumptive use grc1dually increased to reach its maximum at Apr. 0.53 and
0.55 cm/day in 2004 and 2005 which was obtained with irrigation treatments of W₁
and W2. The highest values of W.U.E. for root yield 9.56 and (9.37 kg root beet! m³
water in 2004 and 2005) were obtained With Top cultivar under irrigation treatment W3
and apply-ing of 48 kg K~O/fed and W.U.E. for gross sugar yield (1.16 and 1.30 kg
sugar 1m³water in 2004 and 2005) was found with Top cultivar under irrigation
treatment Wi and using 48 Kg K20 Ifed. The highest values of root yield; 60.67 and 62.18 ton/ha in 2004 and 2005
were obtained with Top cultivar under irrigation treatment W1 and adding 24 kg
K20/fed. The highest values of sucrose 15.25 and 16.75 % in 2004 and 2005 and the
highest values of Purity % (66.69 and 68.20 % in 2004 and 2005) were obtained with
Mezano-poly variety under irrigation treatment W1 and 57 Kg K20/ha. The greatest
gross sugar yield; 7.57 and 8.56 ton/ha in 2004 and 2005 was obtained with Mezano-
poly cultivar under irrigation treatment W1 and adding 24 Kg K20 I fed. in the two
seasons. The highest values of white sugar yield (10.16 and 11.66 % in 2004 and
2005) were obtained with Mezaho-poly cultivar under full irrigation and using 24 Kg
K20 Ifed. The data indicated that optimum potassium decreased the hazards effects
of drought on sugar beet crop at late growing season under the field studied
conditions.