الفهرس 
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Abstract
This study was carried out during the two consecutive seasons of 2016 and 2017 on 16 years old Keitte mango trees budded onto Succary mango rootstock. The selected Keitte mango trees (21 trees) are grown in a private mango orchard located at Kalabsha city, Naser El- Noba, Aswan Governorate and uniform in vigor. The trees are planted at 3x3 meters apart (466 trees / fed) . The texture of the sol is sandy with a water table depth not less than two meters. Drip irrigation system was followed leaving four dippers per each tree and each dipper drains four liters water in one hour.
The scope of this study was examining the effect of spraying nano boron versus normal boron on growth and fruiting of Keitte mango trees grown under Upper Egypt conditions.
This study included seven nano and normal boron treatments beside the control treatment as follows:
1- Control (sprayed with tap water).
2- Spraying boron in the form of boric acid (17 % B) at 50 ppm (0.295 g boric acid/ L water).
3- Spraying boron in the form of boric acid (17 % B) at 100 ppm (0.59 g boric acid/ L water).
4- Spraying boron in the form of boric acid (17 % B) at 200 ppm ( 1.18 g boric acid/ L water).
5- Spraying boron via nano boron at 5 ppm (5 mg boric acid/ L water).
6- Spraying boron via nano boron at 10 ppm (10 mg boric acid/ L water).
7- Spraying boron via nano boron at 20 ppm (20 mg boric acid/ L water).
Each treatment was replicated three time, one tree per each. Spraying of boron was done three times, the first spray at growth start (last week of Feb.) , just after , fruit setting (last week of Apr.) and at one month later (last week of May). Triton B as a wetting agent was added to all spraying solution of boron at 0.05% and spraying was done till runoff.
Complete randomized block design (CRBD) was adopted. each treatment was replicated three times one tree per each.
During both seasons, the following measurements were recorded:
1- Some vegetative, growth aspects of shoot, leaf area and number of leaves per shoot.
2- Some leaf chemical components namely chlorophylls a and b , total chlorophylls , total carotenoids ( mg/ g F.W.) N, P, K, Mg, B, Zn, Fe and Mn.
3- Percentages of initial fruit setting and fruit retention yield per tree and per tons and number of fruits / tree.
4- Some physical and chemical characteristics of the fruits namely weight, height, diameter and thickness of fruit, percentages of flesh, seeds and peels , edible- non- edible portions of fruits, T.S.S., total, reducing and reducing sugars , titratable acidity % ( as g citric acid/ 100 g fruit pulp) and total crude fiber %.
Nearly same the data were obtained during both seasons, it could be summarized under the following topics:
1- Some vegetative growth aspects:
The four growth aspects namely length and thickness of shoot leaf area and number of leaves/ shoot were materially increased with spraying nano boron at 5 to 20 ppm or normal boron at 100 to 200 ppm over the control. Using boron via nano was considerably superior than using normal boron in enhancing these growth aspects slight differences were observed on growth aspects among the high two concentrations of nano and normal boron.
2-Leaf chemical composition
All chemical components namely chlorophylls a & b , total chlorophylls , total carotenoids , N, P, K, Mg, B, Zn, Fe and Mn were considerably enhanced by using boron in both forms compared with the control. Spraying boron via nano was measurably preferred than using normal B in this respect.
3- Percentage of initial fruit setting and fruit retention and yield
Spraying boron in nano or normal forms had an announced promotion on the percentages of initial fruit setting and fruit retention, yield per tree and per fed and number of fruits / tree relative to the control. Using nano boron was superior than using normal boron in this respect. from economical point of view the best results with regard to yield were obtained due to using nano boron at 10 ppm.
4- Fruit characteristics
Generally spraying boron was considerably very effective in improving fruit characteristics in terms of increasing weight, height, diameter and thickness of fruits, T.S.S., total and reducing sugars and vitamin C while decreasing percentage of peel and seeds, total acidity and total crude fiber relative to the control , reducing sugars was unaffected by the present treatments . from economical point of view, the best results with regard to fruit quality were obtained due to spraying the trees three times with nano boron at 10 ppm.