الفهرس 
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Abstract
This study was conducted during two consecutive seasons 2013 and 2014 on forty eight Alphonse mango trees onto polyembryonic mango seedling rootstock. The trees are 16-years old planted at 7 x 7 meter apart. The soil texture of the tested orchard is silty clay grown in a private mango orchard located at Abo Korkas district, Minia Governorate. uniform in vigour .
The selected trees received a basal recommended fertilizer, in addition to the regular agricultural and horticultural practices which were followed in the orchard.
The goal of this study was elucidating the effect of single and combined application of seaweed extract and potassium silicate on fruiting of Alphonse mango trees grown under Minia region conditions.
This study included two factors (A & B). The first factor (A) contained four concentrations of seaweed extract namely a1) 0.0, a2) 0.05 %, a3) 0.1, and a4) 0.2%. The second factor (B) consisted of four concentrations of potassium silicate (25% Si and 10% K2O) namely b1) 0.0, b2) 0.05%, b3) 0.1%), and b4) 0.2%. Therefore, the experiment included sixteen treatments from single and combined applications of seaweed extract and potassium silicate. Each treatment was replicated three times, one tree per each. Seaweed extract and potassium silicate were sprayed three times; annuelly at growth start (1st week of March), just after fruit setting (Middle of April) and at one month later (Middle of May).
The experiment was set in a Complete Randomized Block Design (CRBD) in split plot arrangement in which the four concentrations of seaweed extract and potassium silicate ranked the main and subplots, respectively.
Generally, the following measurements were recorded during the two seasons experimental :
1- Leaf area (cm2) and shoot length (cm) in the Spring growth cycle.
2- Total chlorophylls and carotenoids (mg/100 g F.W.), and percentages of N, P, K, and Mg in the leaves.
3- Percentages of initial fruit setting and fruit retention, number of fruits per tree as well as yield per tree (Kg).
4- Fruit characteristics namely: fruit weight (g), and dimensions (height & diameter & cm), percentages of pulp, seeds, peels, and edible to non-edible portions. In addition, the percentages T.S.S., total, reducing and non-reducing sugars, total acidity% and the fruit content of Vitamin C (mg/100 g pulp).
The obtained data during both seasons could be summarized under the following main topics:
1- Leaf area and shoot length:
The leaf area and shoot length were remarkably stimulated due to treating Alphonse mango trees with seaweed extract and/or potassium silicate each at 0.05-0.2% relative to the check treatment. The promotion was materially associated with increasing concentration of each material. Meaningless stimulation was ascribed to increasing the concentration from 0.1 to 0.2%. Using seaweed extract and potassium silicate together at 0.2% gave the highest values.
2- Leaf chemical composition:
Carrying out three sprays of seaweed extract and/or potassium silicate each at 0.05-0.2% had considerable positive effects on total chlorophylls, total carotenoids (as mg/100 g F.W.), and percentages of N, P, K, and Mg over the check treatment. The promotion was obviously related to the increase in concentrations. No material promotion in these chemical parameters was observed among the higher two concentrations of each material. The maximum values were registered on the trees that were subjected to seaweed extract and potassium silicate combination, each at 0.2%.
3- Initial fruit setting, fruit retention and yield:
A material promotion on the percentages of initial fruit setting and fruit retention as well as yield expressed in weight (Kg) and the number of fruits per tree was observed in response to treating the trees with seaweed extract and/or potassium silicate each at 0.05-0.2% over the check treatment. There was a gradual concentration-dependent promotion on these characters. A slight promotion on these aspects was noticed among the higher two concentrations of each treatment. The best results from economical point of view were obtained when the trees received three sprays of seaweed extract plus potassium silicate each at 0.1%.
4- Fruit Quality:
Treating the mango trees three times with seaweed extract and/or potassium silicate, each at 0.05-0.2% succeeded in improving fruit quality in terms of increasing fruit weight and dimensions (Height & Diameter), percentage of pulp, edible to non-edible portions, T.S.S. %, total, reducing and non-reducing sugars, as well as vitamin C content and decreasing percentages of peels and seeds, and total acidity relative to the check treatment. The promotion on fruit quality was related to the increase in concentrations. The best results with regard to fruit quality were obtained when the trees were treated three times with a mixture of potassium silicate and seaweed extract each at 0.1%.