This investigation was conducted at El-Manyal Village, Talkha District, Dakahlia Governorate, during 2012Governorate, during /2013Governorate, during and 2013Governorate, during /2014 seasons to study the effect of ploughing depth (0.0, 10, 20 and 30 cm), phosphorus fertilizer levels (0.0, 15.5 and 31.0 kg P2O5/fad) and thinning dates (at 20, 30 and 40 days after sowing) on productivity and quality of sugar beet "variety Kawemira". A split-plot design with four replicates was used for each ploughing depth during the two seasons (each ploughing depth was considered as a separate experiment). The main results of this investigation could be summarized as follows: 1-Increasing ploughing depths from 0.0 up to 30 cm significantly increased root fresh weight, root length, total soluble solids percentage (TSS %) as well as root and sugar yields/faddan. On the other hand, it significantly decreased root juice purity percentage in both seasons. 2-Increasing phosphorus fertilizer levels from 0.0 to 15.5 and 31.0 kg P2O5/fad, significantly increased all studied characters in both seasons. 3-Delaying thinning dates from 20 to 30 and 40 days after sowing markedly decreased all studied characters, except root diameter in both seasons. 4-The interactions among studied factors showed insignificant effects, except for the effect of the interaction between ploughing depth and phosphors fertilizer levels on root length in the first season and sugar yield/fad in the second season.Increasing ploughing depth to be 30 cm, adding 31.0 kg P2O5/fad and thinning at the age of 20 days was the suitable recommendation to maximize sugar beet root yield and quality under the environmental conditions of Dakahlia Governorate.

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Two field experiments were conducted at Sakha Agricultural Research Station, Kafr El-Sheikh governorate during the two successive seasons 2005/2006 and 2006/2007 to study the effect of irrigation after 40%, 60% and 80% depletion of available soil moisture (ASMD), and three potassium rates i.e. 0, 24 and 48 kg K2O/fed. on sugar beet yield and water use efficiencies. A split plot design with four replications was used. Irrigation treatments occupied the main plots, while potassium rates arranged in sub-plots.Results showed that increasing soil moisture depletion from 40% to 80% significantly decreased root diameter by 2.9%, root weight/plant by 6.8%, top yield/fed. by 4.6%, root yield/fed. by 4.1% and sugar yield/fed. by 10.0% . On the other hand, root length, total soluble solids and sucrose percentage were increased by 16.1%, 1.2% and 1.20%%, respectively. Increasing potassium application up to 48 kg K2O/fed. significantly increased root length, root diameter , root weight/plant, fresh top and root yields/fed. by 2.2%, 3.0%, 1.7%, 4.5% and 6.3%, respectively, compared to the control treatment.Seasonal water consumptive use values were 61.0 cm, 56.19 cm and 46.38 cm for irrigation after depletion of 40%, 60% and 80% of available water, respectively. In addition increasing K-rates up to 48 kg K2O/fed. slightly increased seasonal water use.Seasonal irrigation water applied values were 68.28 cm (2867.8 m 3 /fed.), distributed on eight irrigations, 62.08 cm (2607.4 m 3 /fed.), distributed on seven irrigations and 55.07 cm (2312.9 m 3 /fed.), distributed on six irrigations, for irrigation after 40%, 60%, and 80% of available soil moisture depletion, respectively.Water use efficiencies values for both root or sugar yields increased as soil moisture depletion increased. While water use efficiencies for both root or sugar yields significantly increased as potassium rate increased up to 48 kg K2O/fed.The mean percentage values of water extracted from the upper 30 cm soil layer were 76.36, 71.78 and 65.18% when sugar beet plants irrigated at 40%, 60% and 80% of ASMD, respectively, A linear slop indicated that each one cm of water applied increased the productivity of root and sugar yields by 74 and 15.7 kg/fed. In addition irrigation water applied is strongly positively correlated with roots yield and negatively to water use efficiencies.Therefore, when water is becoming a limited factor, irrigation at 80% of ASMD could be applied for saving 17.8% of irrigation water against 4.1% and 3.4% reduction in the root and sugar compared to irrigation at 40% of ASMD.

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