YIELD AND QUALITY RESPONSE OF SOME SUGAR BEET VARIETIES TO NITROGEN AND BORON FERTILIZATION IN SANDY SOIL

Two field experiments were carried out at El-Nubaria, El-Buhira Governorate Egypt, during 2017/2018 and 2018/2019 seasons.The objective was to study the effect of foliar applications (0 and 150 ppm /fed of boron) and nitrogen fertilization levels (80, 100 and 120 kg N/fed) on response, yield and quality of three sugar beet varieties (Betamax, Dena and Sara) in sandy soil.A split-split plot design with three replicates was used.The seeds of the three varieties were sown on the 1 st week of October and harvested after 210 days in both seasons.The obtained results showed that foliar application of 150 ppm boric acid/fed recorded a significant increase in root fresh weight and root yield values in both seasons compared to the control.While, foliar application of boron caused a positive reduction effect on impurities (Na, K and alpha amino-N).However, it corrected sugar %, quality of sugar index and sugar yield.Soil application of 100 kg N/fed resulted in significant increases in root fresh weight, roots and tops yields (t/fed) in both seasons, compared with plots treated with 80 kg N/fed, respectively.Fertilizing sugar beet plants with 100 kg N/fed was enough to produce the highest percentages of sucrose, corrected sugar %, quality of sugar index and corrected sugar yield in both seasons.Sara variety showed superior values over the other two varieties in LAI, root fresh weight and roots as well as tops yields t/fed in both seasons.While, Betamax variety attained the least values of the impurity contents in both seasons.The highest means of root weight, roots and top yields resulted from applying boron at 150 ppm boron/fed and 100 kg N/fed in both seasons.Foliar application of 150 ppm boron/fed on Sara variety plants produced the highest values for root fresh weight and root yield in both seasons.Significant positive association was obtained between corrected sugar yield and root yield, leaf area index, top yield, sucrose %, nitrogen and quality index.Corrected sugar yield was highly significantly correlated with root fresh weight and sucrose %; while, significant negative correlation were shown between quality index and both potassium and sodium.These traits will enable the agronomists to realize high income of sugar yield in sugar beet varieties.Use of factor analysis has the potential of increasing the comprehension of the casual relationship of variables and can help to determine the nature and sequence of traits to be evaluation sugar beet varieties trails.Applying these conditions could be recommended for growing sugar beet varieties with 100 kg N/fed fertilization and boron application at the rate of 150 ppm boron/fed increase roots, tops and corrected sugar yield t/fed.