Thesis (M.Sc.) - Cairo University - Institute of African Research and Studies - Department of Natural Resources

To study the ability of soil amendments treatments for improving sugar beet quality and yield with reducing quantities of mineral nitrogen fertilizer and water requirements, two field experiments were carried out at Wadi El-Natrun, El-Beheira governorate, Egypt (30{u00BA} 23ʼ 19.89ʼʼN latitude, 30 {u00B0} 21ʼ 41.06ʼʼE longitude) during 2014/2015 and 2015/2016 growing seasons.. The experimental design was a split-split plot with three replications. Multigerm sugar beet variety Beta Poly Tery was sown. The treatments included: control (without soil amendments), 5 ton/fed compost as organic and 5 ton/fed bentonite as inorganic soil amendments solely or mixed and two nitrogen rates (90 and 120 kg N/fed) on growth, quality and productivity of sugar beet under water stress (100, 75 and 50% of irrigation water requirements) using drip irrigation system. The obtained results showed that increasing water deficit up to 50% of irrigation water requirement significantly decreased root diameter (cm), root and leaves fresh and dry weights (g/plant), leaf area index, net assimilation rate, relative growth rate and crop growth rate as well as top, root and sugar yields (ton/fed), while it increased root length (cm/plant), sucrose %, sugar loss to molasses % and sugar extractable %. Decreasing nitrogen fertilizer from 100% to 75% of recommended rate (120 kg N/fed) significantly decreased root length (cm/plant), root diameter (cm/plant), root and leaves fresh and dry weights (g/plant), leaf area index, net assimilation rate, relative growth rate and crop growth rate as well as root and sugar yields, however, sucrose % and sugar extractable % were increased. In general, application of 5 ton/fed compost or bentonite as well as mixed 2.5 ton/fed of each of them led to significant increase in all traits mentioned above. Application of compost was the best treatment followed by bentonite. The interaction between irrigation without water stress and fertilization by 120 kg N/fed with application of 5 ton/fed compost significantly gave the maximum values of root and sugar yields in the second season. It can be said that application of compost at 5 ton/fed and the recommended N fertilization rate under full irrigation is tremendously recommended

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