الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Currently, reducing synthetic nitrogen fertilizers has become an important issue in sustainable agricultural development due to their environmental hazards as well as now it is known that the boron element has a vital role in the enhancement of sugar beet performance. So a field trial was implemented during 2019/2020 and 2020/2021 to evaluate the possibility of using compost as a partial substitute for mineral nitrogen fertilizer with sugar beet plants sprayed with boron from different sources. Treatments were N-fertilization sources as main plots i.e., 100% of nitrogen recommended dose (NRD) as mineral fertilizer, 75% of NRD as mineral fertilizer plus 25% of NRD as compost, 50% of NRD as mineral fertilizer plus 50% of NRD as compost, 25% of NRD as mineral fertilizer plus 75% of NRD as compost and 100% of NRD as compost as well as different rates and sources of boron represented subplots i.e., control (without B), 1.0 and 2.0 mg B 15 L-1 using Milano (15%boron), 0.5 and 1.0 g B 15 L-1 using borax (11%boron), 0.5 and 1.0 g B 15 L-1 using boric acid (17%boron) as foliar application. The results obtained could be summarized as follows:- 1.Plant performance at the first stage: Individual effect: The different studied ratios between both urea and compost significantly affected N,P,K and chlorophyll content values, where the superior treatment was T1 treatment (100 % of NRD as urea) followed by T2 treatment (75% of NRD as urea +25 % compost) then T3 treatment (50% of NRD as urea +50 % compost) followed by T4 treatment (25% of NRD as urea +75 % compost) and lately T5 treatment (100 % of NRD as compost). The same trend was found for both studied seasons.Interaction effect: Plants received 100% of NRD as mineral nitrogen in form of urea and simultaneously sprayed with B at rate of 1.0 g 15 L-1 of water as boric acid came in the first rank compared to other combination treatments. On the other hand, the plants received 75 % of NRD as mineral nitrogen in form of urea plus 25% of NRD as compost and simultaneously sprayed with B from any source at any rate improve sugar beet performance expressed in total N, P, K (%) and chlorophyll content (SPAD reading value), the contents in leaves at 90 days after sowing better than the corresponding plants received 100 % of NRD as mineral nitrogen.2. Plant performance at a maturity stage (180 days from planting). 2.1. Physical traits and root and top yields:Individual effect:Different combinations between both mineral nitrogen as urea and compost showed significantly effect at physical root traits i.e., root diameter and length (cm), root fresh and dry weights (g plant-1), root yield (ton fed-1), top fresh weight (g plant-1 ), top dry weight (g plant-1) and top fresh yield (ton fed-1), where the highest values of all aforementioned traits were realized when sugar beet plants received 100 % of NRD as mineral nitrogen as urea followed by that of plants received 75% of NRD as mineral nitrogen in form of urea +25 % compost then the values of plants received 50% of NRD as urea +50 % compost then the values of plants received 25% of NRD as urea +75 % compost, while the lowest values were recorded with plants received 100 % of NRD as compost. 2.2. Quality traits and sugar yield:Individual effect:It is quite obvious that different studied ratios between both urea and compost significantly affected values of chemical constituents in roots i.e., N, P, K, Na and -amino N (%) as well as juice quality i.e., sucrose(%), TDS (%), purity (%), impurity (%), sugar yield (ton fed-1), sugar recovery (%), recoverable sugar yield (%),sugar loss(%),R.S.Y (ton fed-1), sugar loss yield (ton fed-1) and quality index (%) of sugar beet at a maturity stage (180 days from planting), where the sugar beet plants received 100 % of NRD as urea possessed the highest values of all above mentioned studied traits excluding purity and quality index (%).CONCLUSION:Generally, from the results, under the conditions of this study, it could be concluded that combination between mineral and organic fertilizers as a source of N under foliar application of B may be suppressed environmental hazards of synthetics fertilizers and simultaneously is beneficial for sugar beet plants. Therefore, the study recommends fertilizing sugar beet plants with 75% of nitrogen recommended dose as mineral nitrogen in form of urea with a compensation using 25% of nitrogen recommended dose as compost fertilizer under spraying plants with any source of boron to obtain the highest productivity per unit area as well as the best quality.