الفهرس 
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Abstract
The present work was carried out for two consecutive seasons (2010 and 2011) at the farm of Horticulture Research Station at El-Kanater El- Khaireia Barrage, Kalyubeia Governorate, Egypt, on mango trees (Zebda cultivar). Thirty six fruitful trees of about seven years old were selected. The trees were healthy, nearly uniform in their shape, vigour and size as possible. The main objective of this experiment was throw some light on the influence of soil inoculation with three bacterial strains (Azotobacter chroococcum, Azospirillm lipoferum and Bacillus polymixa) solely or combined with two sources of chemical nitrogen fertilizers (ammonium nitrate or ammonium sulphate) on vegetative growth, leaf mineral content, fruit setting, fruit retention %, yield as well as physical and chemical properties of Zebda mango fruits. The experiment included the following twelve treatments: 1. Ammonium nitrate NH4NO3 solely at 3.0 Kg {1000 gm. N} /tree a year. 2. Ammonium sulphate (NH4)2SO4 solely at 5.0 Kg {1000 gm. N}/tree a year. 3. Azospirillm lipoferum (AL) inoculation solely. 4. Azotobacter chroococcum (AC) inoculation solely. 5. Bacillus polymixa (Bp) inoculation solely. 6. (Al) inoculation +1.5 kg {500 gm. N} Ammonium nitrate. 7. (Al) inoculation +2.5 kg {500 gm. N} Ammonium sulphate. 8. (Ac) inoculation + 1.5 kg Ammonium nitrate. 9. (Ac) inoculation +2.5 kg Ammonium sulphate. 10. (Bp) inoculation + 1.5 kg Ammonium nitrate. 11. (Bp) inoculation + 2.5 kg Ammonium sulphate. 12. Control (adopted N fertilization in the farm). Each treatment was replicated three times, one tree per each. The experiment was set in a randomized complete block design. The corresponding amount of each mineral N fertilizer for a given treatment was fractionated into 3 equal doses, applied in Feb., April and June by mixing with the soil surface layer (20.0 cm depth) surrounding the trunk till the external end of canopy shade . The soil inoculation with three bacterial strains was applied twice a year in March and May. For evaluation the effect of bio and mineral nitrogen fertilizers on vegetative growth, leaf mineral content and fruiting of Zebda mango trees, the following measurements were recorded: 1- Shoot length (cm.) 2- Number of leaves/shoot. 3- The leaf area (cm2) in the spring growth cycle. 4- Percentage of leaves dry weight per twig. 5- Percentages of N, P and K in the leaves. 6- Percentage of fruit setting. 7- Percentage of retention fruits. 8- Yield/tree expressed in weight (kg) and number of fruits/tree. 9- Some physical characters of the fruits i.e. fruit weight (g.), fruit size (cm3), fruit shape index (fruit length (cm)/fruit diameter (cm), peel thickness (cm), seed weight (%) and fruit firmness. 10- Some chemical characters of fruits i.e. total soluble solids %, total acidity %, total soluble solids/acid, total sugar % and ascorbic acid content (mg/ 100g pulp).