الفهرس 
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Abstract
The present study was carried out during 2018 and 2019 seasons, on Sewy date palm grown under well drained sandy soil. However, the water table depth is not less than two meters. The select orchard was located at El-Kharga Oasis - New Valley Governorate - Egypt. The palms were 15 years old at the start of this experiment, where the soil texture is sandy loam and water table depth is not less than 2 meters. The chosen palms were planted at 8 X 8 meters apart and irrigated throw drip irrigation system using underground well water.
The chosen palms are subjected to regular horticulture practices that were commonly applied in date palm orchards including fertilization, irrigation, hoeing and pest management. In order to study the effect and the suitable dose of different sources of sulfur on Sewy date palm, three sources of sulfur namely: agriculture sulfur, liquid sulfur and micronized sulfur were used in this experiment, each one was used at three gradual doses namely; 200 ppm, 300 ppm and 400 ppm. Then, this study included the following ten treatments from sulfur sources and concentrations.
As follow the ten treatments were arranged:
1-Control (0.0% sulfur, palms sprayed with water).
2-Spraying agriculture sulfur at 200 ppm
3-Spraying agriculture sulfur at 300 ppm
4-Spraying agriculture sulfur at 400 ppm
5-Spraying liquid sulfur at 200 ppm
6-Spraying liquid sulfur at 300 ppm
7-Spraying liquid sulfur at 40 ppm
8-Spraying micronized sulfur at 200 ppm
9-Spraying micronized sulfur at 300 ppm
10-Spraying micronized sulfur at 400 ppm
All treatments were replicated three times, while, each replicate was represented by one palm. Triton B was used as a wetting agent at 0.05% with all treatments.
Experimental design:
Complete randomized block design (RCBD)were used in this experiment. The following parameters including vegetative growth, leaves pigments, leaf essential mineral contents, yield and its component as well as physical and chemical characters of fruits were measured during this study.
The important results during this investigation could be summarized in the following topics:
1-Vegetative growth parameters: During the two experimental seasons, the obtained data showed that sprayed Sewy date palm with the three sources of sulfur at different concentrations (200 ppm, 300 ppm and 400 ppm) was capable to varied significantly the vegetative growth in terms of number of green leaves/palm, number of leaflets/leaf, leaflet area (cm2) and leaf area (m2). Using the sulfur in form of micronized element present superiority than using the sulfur in the two other forms (agriculture sulfur or liquid sulfur).
Furthermore, regardless the form of sulfur used, increasing the concentration of sulfur from 0.0 to 400 ppm was parallel to gradual increasing all the vegetative characteristics during the two experimental seasons. However, the palms received sulfur at 400 ppm in form of micronized sulfur present the highest number of green leaves/palm, number of leaflets/leaf, leaflet area (cm2) and leaf area (m2) in both experimental seasons.
However, non-significant differences were observed between the two highest concentrations (300 ppm and 400 ppm). Contrary, untreated palms present the lowest number of green leaves/palm, number of leaflets/leaf, leaflet area (cm2) and leaf area (m2), during the two experimental seasons.
2- Leaf main pigments and mineral contents:
Regardless the source of sulfur used, during the both experimental seasons a promotion effect was observed on chlorophylls a, chlorophyll b and total carcinoids (mg/100g F.W.), as well as leaves macro nutrients (N, P, and K %) and leaves micro nutrients (Fe, Zn, Mn and Cu ppm) contents.
Further, concerning all pigments (chlorophyll a, b and total carotenoids), using the sulfur in form of micronized sulfur showed superiority rather than using the sulfur in other forms or untreated palms. Increasing the sulfur concentration from 0.0 to 400 ppm was parallel with a gradual increasing in main pigments and all essential studied elements. However, palms received the highest sulfur concentration (400 ppm) present the highest main pigments and essential macro and micro elements in their leaves. While regardless the forms of sulfur, non-significant differences were recorded between the two highest concentrations neither in the first nor in the second season. Contrary of this, untreated palms present the lowest main pigments and mineral elements in their leaves. These data were true during both experimental seasons.
3- Yield as well as bunch weight.
Treating Sewy date palm with different sources and different concentrations of sulfur was followed by stimulating bunch weight in kg and yield (kg)/palm significantly increased rather than control treatment, during the two experimental seasons. This stimulation was related to increasing sulfur form and concentration.
The obtained data showed that, regarding the three examined sulfur forms, the palms received sulfur in form of micronized sulfur showed superiority in both characters (bunch weight and yield (kg)/palm) than those received the sulfur in form of agriculture sulfur or liquid sulfur, during the two experimental seasons.
Regardless the sulfur source, the palms received sulfur at 400 ppm present the highest values of bunch weight and yield kg/palm. However, non-significant differences were observed between the two highest concentrations (300 ppm and 400 ppm), neither in the first seasons nor in the second season.
Furthermore, the palms received 400 ppm micronized sulfur present the highest punch weight and yield (kg/palm). Contrary, untreated palms present the lowest values of bunch weight (kg) and yield (kg/palm), these data were true during the two seasons.
4- Fruit Physical properties:
Spraying sulfur at gradual concentrations (200, 300 and 400 ppm) in three different sources (agriculture, liquid and micronized sulfur) was very effective in all fruit physical properties (fruit weight, fruit length and fruit diameter) of Sewy date palm, rather than untreated palms. The data showed that all sulfur sources and concentration significantly promoted all physical properties rather than untreated palms.
This promotion in terms of increasing fruit weight (g), fruit length (cm) and fruit diameter (cm) were parallel with increasing sulfur concentrations from 0.0 to 400 ppm, these data were true during the two experimental seasons. Furthermore, the palms received the highest concentration of sulfur in form of micronized sulfur present the best physical fruit properties, during the two seasons. Contrary, untreated palms present lowest physical properties in their fruits, during the two experimental seasons. However, non-significant differences were observed between the two highest concentrations, neither in the first season nor in the second season.
5- Fruit chemical properties:
Obtained data showed that, spraying Sewy date palm with sulfur at gradual concentrations (200, 300 and 400 ppm) in three different sources (agriculture, liquid and micronized sulfur) caused a significant enhancing of fruit TSS%, Total sugars and reducing sugars% in comparison with untreated palms, during the two experimental seasons. However, regardless the concentration used, using the sulfur in form of micronized was superior to the other forms (agriculture and liquid sulfur).
Contrary of this, regardless the source of sulfur used, increasing sulfur concentration was parallel related to increasing TSS%, reducing sugars% and total sugars%. The palms received the highest concentration of micronized sulfur present the highest TSS%, reducing sugars% and Total sugars%. However, non-significant differences were observed between the two highest concentrations (300 and 400 ppm), during the two experimental seasons.
On the opposite side, regardless the source of sulfur, increasing sulfur concentration from 200 ppm to 400 ppm was parallel with significant decrease in fruit total acidity %, total tannins% and crud fiber % in both experimental seasons. However, untreated palms present the highest concentrations in their fruits. on the other hand the palms received 400 ppm from sulfur in form of micronized sulfur present the lowest total acidity %, total tannins % and crud fibers % in their fruits. These data were true during the two experimental seasons.
In all physical and chemical properties, non-significant differences were observed between the two highest concentrations. Then, in economical view, it is may be logically recommended to spraying Sewy date palm with 300 ppm sulfur in form of micronized sulfur.