الفهرس 
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Abstract
This study was carried out during two successive seasons of 2013 and 2014 in a private orchard, at El-Kharga Oasis, New Valley Governorate, Egypt. Sewy date palm trees of 12 years old grown in sandy loam soil. Eighty one female palms trees of healthy with no visual nutrient deficiency symptoms, nearly uniform in shape, size and productivity were chosen and devoted to achieving this experiment. The experiment involved three studied factors (A, B and C). The first factor (A) included the effect of leaf/bunch ratio. Both leaves and bunches were pruned to attain a definite leaf/bunch ratio. The treatments were as follows: A1: 10:1 leaf/bunch ratio, A2: 8:1 leaf/bunch ratio, A3: 6:1 leaf/bunch ratio. The number of bunches left on each palm was 9 bunches by removing excess earliest, latest and small clusters. The retained bunches were thinned to constant number of strands. The second factor (B) involved three treatments of magnesium fertilization, as follow: B1- 500 g magnesium sulphate (MgSO4 Mg 9.9%) (B1). B2- 750 g magnesium sulphate (MgSO4 Mg 9.9%) (B2). B3- 1000 g magnesium sulphate (MgSO4 Mg 9.9%) (B3). Soil application of magnesium fertilizer (MgSO4, Mg 9.9%) was divided into equal three doses applied three times a year i.e. April, June, July in each season. The third factor included the following three treatments from nitrogen fertilization, as follow: C1- 1000 g nitrogen/palm (2.17 kg urea, 46.5%) C2- 1250 g nitrogen/palm (2.71 kg urea, 46.5%) C3- 1500 g nitrogen/palm (3.26 kg urea, 46.5%) Soil application of nitrogen fertilizer as urea (46.5% N) was divided into three equal batches applied three times a year i.e. March, May and July in each season. Calcium superphosphate (15.5% P2O5) at 1.5 kg/palm and 1.0 kg potassium sulphate (48% K2O)/palm were added. Calcium superphosphate was added once in circle surrounded each palm on the middle of December. In addition, potassium sulphate was added at two equal batches on middle of May and July. Then, twenty seven treatments were involved in this experiment. The experiment was designed as split split plot arrangement in CRB design with three replicates for each treatment and one date palm each. In general, the following measurements were determined during the two studied seasons. 1- Number of newly growing leaves were determined at the end of growth season. 2- Leaf mineral content. 3- Yield: All bunches were harvested at tamer stage, bunches of each palm were picked and weighed, then the yield/palm (kg) was recorded. 4- Fruit physical and chemical properties. The obtained results during the two studied seasons could be summarized under follow main items. 1- Effects on vegetative Concerning the effect of leaf/bunch ratio on these traits, the results reveal that new leaf No./palm and leaf length as well as pinnae area and total leaf area were significantly increased with leaf/bunch ratio increased. The leaf traits were significantly increased as leaf/bunch ratio was 10 or 8 leaves/bunch compared to 6 leaf/bunch. New leaf No./palm and leaf length as well as pinnae area and total leaf area were significantly increased with magnesium doses increased from 500 to 1000g MgSO4/palm. Raising the magnesium dose from 750 to 1000 g MgSO4/palm failed to show any significant increase in such leaf traits recorded new leaves/palm. Leaf growth parameter studied of Sewy date palms significantly responded to interaction between the leaf/bunch ratio and magnesium applications. All combination of leaf/bunch ratio either 8:1 or 10:1 significantly increased the new leaf number/palm, leaf length, pinnae area and total leaf area. New leaf/palm, leaf length, pinnae area and total leaf area were significantly increased by increased the nitrogen doses application from 1000 to 1500 g nitrogen/palm. Using 1250 or 1500 g nitrogen significantly increased these studied traits compared to use 1000 g nitrogen/palm. The highest values of these studied traits were recorded due to fertilized with 1500 g nitrogen/palm compared to other applications. Moreover, no significant effect due to fertilization via either 1250 g (C2) or 1500 g nitrogen/palm (C3). Since, raising nitrogen application from 1250 g (C2) to 1500 g (C3) failed to show any measurable increase in these studied leaf traits. Generally, all combinations of leaf bunch ratio, 10:1 (A1) or 8:1 (A2) combined with 750 g MgSO4 (B2) or 1000 MgSO4 (B3) along nitrogen level 1250 (C2) or 1500 g (C3) nitrogen fertilization significantly increased the new leaf/palm, leaf length, pinnae area and total leaf area. All combination with nitrogen 1500 (C3) gave the highest values of these studied leaf traits compared to other combination. Moreover, no significantly difference within traits due to reduced leaf/bunch ratio to 8:1 (A2), fertilized with 750 MgSO4 (B2) and 1250 nitrogen (C2). In general over seen these results declared that the improvement occurred due to interaction effects was more effect than due singly treatments, any pruning magnesium and nitrogen fertilization. Therefore, it could be concluded that from economical point of view it is suggested to prune Sewy date palm to 8 leaf/bunch combined with fertilized by 750 g (MgSO4) and 1250 g nitrogen/palm to improve the leaf trait. 2- Effects on leaf nutrient content: Leaf, N, P, K and Mg concentration significantly increased with leaf/bunch ratio increased. Highest values of leaf N, P, K and Mg percentage were recorded for high leaf/bunch ratio 10:1. Pruning to 8 or 10:1 leaf/bunch ratio significantly increased the N, P, K and Mg percentage compared to leaf/bunch ratio 6:1. No significantly difference in these macronutrients due to raise leaf/bunch ratio from 8:1 to 10:1 ratio. Percentage of leaf N, P, K and Mg significantly increased with magnesium level increased from 500 to 1000g (MgSO4). Using magnesium sulphate at 750g (B2) or 1000g/palm (B3) significantly increased N, P, K and Mg in the leaves compared to use 500 magnesium sulphate (B3). Raising the MgSO4 level from 750 to 1000 g/palm failed to show any significantly increased in these macronutrients. Nutrient contents of leaves significantly responded to interaction between leaf/bunch ratio and magnesium application. Most combination of leaf/bunch ratio either 8:1 or 10:1 ratio with fertilized by 750 or 100g MgSO4 significantly increased the percentages of N, P, K and Mg in leaves. The maximum values of N% in leaves were (1.91 & 1.92) on the palm that fertilized with 1000g MgSO4 and pruned to 10 leaf/bunch (A1B3) in the two studied seasons respectively, as well as, the highest values of P% (0.23 & 0.23%) and K% (1.37 & 1.40%) were recorded on treated palms by (A1B3) during the two studied seasons, respectively. Also, the highest values of Mg% were (0.46 & 0.47%) on the palms which treated by A1B3 in both studied seasons, respectively. On the other hand, the minimum values of N% in leaves (1.78 & 1.80%), P% (0.15 & 0.16%), K% (1.18 & 1.20%) and Mg% (0.33 & 0.34%) on the palms that pruned to 6:1 ratio fertilized by magnesium sulphate (A3B1) during the two studied seasons, respectively. Percentage of N, P, K and Mg in leaves were significantly affected by various doses of nitrogen fertilization. Using 1250 g (C2) or 1500 g nitrogen/palm (C3) significantly increased the contents of N, P, K and Mg in leaves compared to using 1000g nitrogen/palm (C1). Moreover, no significant differences due to fertilize with either C2 or C3. Using 1500g nitrogen palm (C3) gave the highest values of these nutrients compared to other doses application. Generally all combinations of leaf/bunch ratio 8 or 10:1 ratio (A1 & A2), magnesium sulphate at 750 or 1000 g/palm (B2 & B3) and nitrogen fertilization dose at 250 or 1500 g/palm (C2 & C3) were significantly increased the percentages of N, P, K and Mg in leaves. All combination with 1500 g nitrogen/palm gave the highest values of N, P, K and Mg leaf contents compared to other combination. The highest N and Mg contents was found on palms that treated with A1B3C3 (1.95 & 1.95%) and Mg (0.48 & 0.47%) during the two studied seasons. On other hand, the least values of N (1.70 & 1.80%) and Mg (0.30 & 0.34%) were recorded on palms that pruned to 6:1 ratio and fertilized with 500g MgSO4 and 1000g nitrogen/palm during the two studied seasons, respectively. Hence the corresponding increment percentage were (13.37 & 12.00) and (60.00 & 54.64%) during the two studied seasons, respectively. 3- Effects on yield components Bunches No./palm, bunch weight and yield/palm took similar tendency and increased as the level of leaf/bunch ratio increased during two studied seasons, leaf/bunch ratio 8 or 10:1 significantly increased the born bunch, bunch weight and yield/palm compared to use 6 leaves per bunch. The highest values of studied yield components were recorded on the palms that pruned to 10 leaves per bunch. Yield components significantly affected with the interaction between leaf/bunch ratio (A) and magnesium fertilization (B). In this respect, combined of 10 leaves/bunch (10:1) with 1000 g MgSO4 (A1B3) gave the highest bunch weight (9.69 & 10.26 kg) and yield/palm (87.15 & 92.34 kg/palm) compared to other combination during the two studied seasons, respectively. Contrary (A3B1) gave the lowest values of bunch weight (7.25 & 7.50 kg) and yield/palm (65.28 & 67.50 kg/palm). Number of new inflorescences, bunch weight and yield/palm significantly increased to response of increased the add nitrogen from 1000 g to 1500 g/palm. Increasing add nitrogen from 1250 (C2) to 1500g (C3) caused an insignificantly increased on these traits. The maximum value of such traits were found in palms fertilized with 1500 g nitrogen per each. Raising the nitrogen level from 1250 to 1500 g/palm failed to show any significant increased in yield components. The bunch weight and yield/palm significantly increased with magnesium level increased from 500 to 1000g (MgSO4). Raising the MgSO4 level from 750 to 1000 g/palm failed to show any significant effect in yield components. Fertilizing with 750 or 1000 g MgSO4 significantly, increased the bunch weight and yield/palm compared to fertilize by 500g MgSO4/palm.