YIELD AND QUALITY OF SUGAR BEET AS AFFECTED BY ZINC FOLIAR APPLICATION UNDER DIFFERENT NITROGEN FERTILIZATION LEVELS

      Two field experiments were conducted in Sakha Research Station Kafr El-Sheikh Governorate during 2010 /2011 and 2011/2012 seasons to study the effect of the combination between three nitrogen levels ( 60 , 90 and 120 kg / fed ) and four foliar zinc levels ( 0 , 0.5 , 1  and 1.5 g/ l as Zn-EDTA ) on some physiological properties , yield and quality of sugar beet.      
The obtained results proved that :

The increase of N level up to 120 kg/ fed significantly increased root length and diameter as well as fresh weight/plant , leaf area , leaves zinc uptake , juice impurities content (K, Na and α-amino N) and yields of top and root (ton / fed) whereas , sucrose % , extractable sugar % , purity % and sugar yield  were decreased in both seasons.
The middle dose of nitrogen (90 kg N /fed) was the superior as compared with the highest dose (120 kg N/fed)  on sucrose % , extractable sugar % , purity % and sugar yield as well as gave the lowest juice impurities content and sugar losses to molasses in both seasons .
The increase of zinc level up to (1.5g/l) significantly increased all studied traits in both seasons except for N leaves content in the 1^st season only as well as gave the lowest juice impurities content and sugar losses to molasses.
Fertilization beet plant at the rate of 90 kg N/fed + 1.5 g Zn/l was enough to achieve the highest sugar yield (4.22 and 4.57 ton/fed) ,whereas the increase of N fertilization at the rate of 120 kg N / fed + 1.5 g Zn/l was necessary to attain the highest yields of top (10.01 and 10.78 ton/fed), and root (28.77 and 32.60 ton/fed ) in the 1^st and 2^nd seasons respectively .

       Therefore, it could be recommended that fertilization beet plant at the rate of 90 kg N/fed + 1.5 g Zn/l  foliar application maximized  sugar yield and technological parameters .