الفهرس 
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Abstract
This investigation was carried out during two successive seasons 2017 and 2018 on thirty two derived offshoots Sakkoti and Bertimoda date palms (sixteen palms from each cultivar), uniform in vigor and free from insects and diseases. The palms were ten years and grown in private orchard located at Edfu, Aswan Governorate where the soil texture is loamy clay and well drained water. The chosen palms were planted at 8 X 8 meters apart and irrigated through surface system using Nile water.
The overall aim of this experiment was to improve understanding of the influence of spraying abscisic acid at different concentrations on some vegetative growth characteristics, nutritional status of palms, and yield as well as fruit physic - chemical characteristics of Sakkoti and Bertimoda date palms.
In order to study the effect and the suitable dose of ABA on Sakkoti and Bertimoda date palm, four doses of ABA namely; 0.0 ppm, 150 ppm, 300 ppm and 450 ppm were examined on the present investigation. This study included the following eight treatments from two cultivars and 4 concentration of ABA: The two examined cultivars were received ABA three times yearly: just after fruit setting, during Kimri stage and one month later.
As follow the eight treatments were arranged:
• 0.0 ppm ABA, sprayed Sakkoti palms with tap water.
• 0.0 ppm ABA, sprayed Bertimoda palms with tap water.
• Spraying Sakkoti palms with ABA at 150 ppm.
• Spraying Sakkoti palms with ABA at 300 ppm.
• Spraying Sakkoti palms with ABA at 450 ppm.
• Spraying Bertimoda palms with ABA at 150 ppm.
• Spraying Bertimoda palms with ABA at 300 ppm.
• Spraying Bertimoda palms with ABA at 450 ppm.
Each treatment was replicated four times, one palm per each. Wetting agent, Triton B, was added to all treatments of ABA.
The experiment was arranged in split plot design with eight treatments; each one replicated four times, one palm per each.
During booth experimental seasons, the following parameters were recorded:
1- Leaf morphology: Morphology measurements of leaves were studied using four full sized leaves/palm, included leaflet length and width of leaf (cm) on 8 leaflets per leaf. Leaflet area (cm2) was determined. Leaf area (m2) was calculated by multiplying the number of leaflets/leaf by the average area of leaflet. Then, total surface area of palm (m2) was estimated by multiplying number of leaves/palm by the leaf area (m2). Number of spines per leaf as well as spine length (cm) was also recorded.
2- Measurements of leaves main pigments: Chlorophyll a, b, and total chlorophyll as well as total carotenoids were determined in mature and fresh pinnae from the six month old leaves.
3- Determination of macro and micro elements (N, P, K, Mg, Zn and Fe) in leaves: A six months old labeled leaf per palm was removed (at the first week of August annually).
• Nitrogen was determined by the modified microkejldahl method.
• Phosphorus was determined by using colorimetric method.
• Potassium was flam-photometrically determined.
• Mg, Zn and Fe were by determined using atomic absorption method.
4- Yield and bunch weight: Bunches of Sakkoti and Bertimoda date palms were picked at the optimum commercial harvesting time. The yield of each palm was recorded in terms of weight in kilograms per palm, by multiplying the average bunch weight (kg) by total number of bunches per palm (ten bunches).
5: physical and chemical characteristics of fruits: samples of one hundred dates from the yield of each palm were taken randomly and the following physical and chemical characteristics were measured:
5-1: Measurement of fruits physical properties:
• Average weight of fruit (g) estimated, Fruit dimensions (height and diameter (cm), Edible (flesh weight) to non-edible portions (seed weight) were determined.
5-2: Determination of fruits chemical properties:
The following chemical properties were determined:
• Percentage of total soluble solids (T.S.S %) by using hand refractometer.
• Percentage of total and reducing sugar in the juice by using Lane and Eynone volumetric method.
• Percentage of total acidity, by titration against 0.1 NaOH using phenolphthalein as an indicator.
• Crude fiber contents: Determination of crude fibers content was achieved using acetic acid glacial and nitric acid at 10 : 1 solution.
The most important obtained results during the two experimental seasons could be summarized as follows:
1- Vegetative growth characteristics:
During the present study spraying the two examined cultivars with ABA at 0.0, 150, 300, 450 ppm failed to varied some vegetative growth significantly such as leaf length ”m” (in the first season), leaf width “m” (in the first season), leaflet area (cm2), numbers of leaflet / leaf and number of spines/leaf. On the opposite side, leaf length and width (m) during in the second season. leaf area (m2), total surface area (m2/palm) and spines length (cm) were significantly and gradual decrease as a result of increasing the applied concentration of ABA from 150 ppm to 450 ppm. However, the palms received the highest ABA concentration (450 ppm) present the lowest leaf area (m2), total surface area (m2/palm) and spine length (cm), during the two experimental seasons. Concerning all studied vegetative growth, the differences between ABA concentrations was clearer than those between the two cultivars.
2- Leaf main pigments and mineral contents:
During the two experimental seasons a promotion effect was observed on leaf chlorophylls a & b, total chlorophylls and total carcinoids contents, as well as leaf macro (in %) and micro (in ppm) elements contents, except the case of differences between the two cultivars in potassium contents, during the two experimental seasons. The promotion was parallel with increasing ABA concentration from 0.0 to 450 ppm. However, spraying Sakkoti and Bertimoda palms with ABA at 450 ppm gave the maximum values of chlorophyll a, b, total chlorophylls and total carotenoids (mg/100 g F.W) as well as N, P, Fe, Zn and Mn ppm, the data was true in both experimental seasons. Sakkoti cultivar present superiority in chlorophyll a, chlorophyll b, total and chlorophyll as well as P % than Bertimoda cultivar. Contrary, leaves of Bertimoda cultivar present superiority in total carotenoids contents (mg/100g F.W.) and N%, during both experimental seasons respectively.
While, non-significant differences were recorded neither between the two cultivars nor between ABA concentrations, in both seasons. Furthermore the interaction between the studied factors (cultivars and ABA concentrations) was significant. However, palms received ABA at 450 ppm present the highest main pigments and mineral elements in their leaves. Contrary, untreated palms present the lowest main pigments and mineral elements in their leaves. The data were true during the two experimental seasons.
3-Fruit setting % and fruit retention %
Increasing the applied concentration of ABA from 0.0 to 450 ppm was associated with gradual and significant increasing in fruit sett and retention %, during the two seasons. Regarding the two examined cultivars, Bertimoda cv. present a higher and significant response of ABA spraying in concern of fruit sett % during the two seasons than this of Sakkoti cultivar. Fruit retention % takes an opposite direction, where the response of Sakkoti cv. present higher and significant fruit retention % than those of Bertimoda cv., during the two experimental seasons. However, the palms of the two cultivars received 450 ppm of ABA present the highest fruit setting % and fruit retention % during the two seasons. In the opposite side, untreated palms present the lowest fruit sett and fruit retention %, in both experimental seasons.
4- Yield as well as bunch weight.
Treating Sakkoti and Bertimoda cultivars with ABA at 150 to 450 ppm was followed by stimulating bunch weight (kg) and yield/palm (kg) significantly increased relative to the control treatment, during the two seasons. This stimulation on these two parameters was related to the increase in ABA concentrations from 150 to 450 ppm. Regarding the two examined cultivars, the response of Sakkoti cultivar shows superiority in both characters (bunch weight and yield/palm) than those of Bertimoda cultivars, during the two experimental seasons. However the palms received ABA at 450 ppm present the highest values of bunch weight and yield kg/palm. Contrary of this untreated palms present the lowest values of bunch weight (kg) and yield (kg/palm), during the two seasons.
5- fruit Physical and Chemical properties:
There was an obvious on physical (fruit weight, fruit dimensions and flesh %) and chemical characteristics (TSS%, total sugars %, reducing sugars%, non-reducing sugars%, total acidity and crude fibers%) of Sakkoti and Bertimoda dates were significantly promoted as a results of spraying ABA at 150, 300 and 450 ppm three times yearly. This promotion in terms of; increasing fruit weight, fruit dimensions, flesh %, TSS%, Total sugars, reducing sugars and non-reducing sugars and decreasing the total acidity and crude fibers % were parallel with increasing ABA concentrations from 0.0 to 450 ppm, these data were true during the two experimental seasons. Furthermore, Sakkoti and Bertimoda palms received the highest ABA concentration of present the best physic – chemical fruit properties, during the two seasons. Contrary, untreated palms present lowest physic – chemical properties in their fruits, in both seasons.
Conclusion:
It is strongly recommended to spray Sakkoti and Bertimoda date palms grown in loamy clay soil under Aswan Governorate conditions, and resembling conditions, with abscisic acid (ABA) at 450 ppm three times at just after fruit sett, at kamary stage and one month later, in order to improve the nutritional status, yield and fruit physico – chemical properties.