الفهرس 
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Abstract
A pot experiment was carried out at Experimental Station of the Medicinal and Aromatic Plants, Fac. Agric., Mansoura Univ. during two successive summer seasons of 2014 and 2015 to study the effect of different rates of mineral nitrogen fertilizer (ammonium sulfate (20.6%N) at 0, 50,100 and 150 kg/fed) and some soil additives (rice straw compost (R.S.C), town refuse compost (T.R.C.) and bio-fertilizer Nitrobien) as well as their interactions on vegetative growth, tuber yield, fixed oil content and chemical constituents of tiger nut (Cyperus esculentus L.) plant in order to investigate its growth performance and to improve its production.Before planting, tiger nut tubers were soaked in a tap water for 4 days to facilitate germination, and the water was changed every day. After soaking, tubers were taken out of water and kept in a basket until they began to sprout between 7 and 12 days after soaking. Tiger nut tubers were planted on mid-April in both seasons in pots of 40 cm diameter. Each pot was filled with 15 kg sandy loam soil, and tubers were planted at a rate of 4 tubers /pot. The layout of the experiment was factorial experiment in a randomized complete block design with (24) treatments each treatment contains three replicates (pots) with a total of 72 pots. The obtained results could be summarized as follow: I-Effect of nitrogen fertilizer levels : The highest level of nitrogen fertilizer (150 kg/fed) ammonium sulfate significantly enhanced all vegetative growth characters expressed as plant height (cm), number of tillers per pot, herb dry weight (g/pot) and some harvesting characters including tuber yield (g/pot), and fixed oil yield (ml/pot) as well as protein % in tubers , but the maximum number of tubers per pot, fixed oil % as well as carbohydrates % in tubers were obtained from plants treated with nitrogen fertilizer at rate of (100 kg/fed) ammonium sulfate compared with the other levels of nitrogen fertilizer, while the least values of these characters were obtained from the untreated plants with nitrogen fertilizer. II-Effect of soil additives (compost types and bio-fertilizer):-R.S.C or T.R.C fertilizer at the rate of 15m3/fed plus Nitrobien at the rate 4 kg/fed had a positive effect on all vegetative growth characters expressed as plant height (cm), number of tillers per pot, herb dry weight (g/pot) and harvesting characters including number of tubers per pot, tuber yield (g/pot) and fixed oil content as well as protein and carbohydrates % in tubers, when compared the other treatments. R.S.C. fertilizer had the best positive effect on all studied characters in both seasons when compared to either T.R.C. or Nitrobien treatment.III-Effect of the interaction between N fertilizer levels and soil additives: The combined treatment of 50 kg/fed ammonium sulfate fertilizer combined with R.S.C. or T.R.C. plus Nitrobien was more effective on all traits studied than using the full dose of inorganic N-fertilizer (150 kg/fed) alone. Such application could reduce the amount of inorganic N -fertilizer and can save the use of two thirds of the inorganic N -fertilizer. The combined treatment of 150 kg/fed ammonium sulfate fertilizer with R.S.C. plus Nitrobien was the most effective treatment to improve all vegetative growth characters and some harvest characters including tuber yield (g/pot), fixed oil yield (ml/pot) and protein % in tubers followed by the same combination using 100 kg/fed ammonium sulfate instead of 150 kg/fed ammonium sulfate with non-significant differences between the two treatments. The combined treatment of 100 kg/fed ammonium sulfate with R.S.C. plus Nitrobien was more effective on number of tubers per pot, fixed oil % and carbohydrates % than any individual or combination treatments in both seasons. The gas liquid chromatography (G.L.C.) analysis identified twelve fatty acids in tiger nut fixed oil: six unsaturated fatty acids, as ranged from 78.19 to 79.21% of the oil and six saturated fatty acids, as ranged from 20.80 to 21.81%. The main components of the unsaturated fatty acids were oleic acid (67.42 - 69.19 %), linolenic acid (9.42 – 10.27%), while the main saturated fatty acids were palmatic acid (12.29 – 13.26 %) and stearic acid (6.60 – 8.13%). Conclution: On the basis of previous results, it can be concluded that the crop fertilized with 100 kg/fed ammonium sulfate plus 15m3/fed R.S.C. and bio-fertilizer Nitrobien at 4 kg/fed (incorporate to the soil) appeared to be most appropriate and suitable application for harvesting a good crop of tiger nut tubers and fixed oil quality with maximum value of unsaturated fatty acid under the conditions of this experiment. It is also possible to recommend planting the tiger nut plant in the newly reclaimed lands, which makes the expansion of its planting, does not affect the summer strategical crops, as well as the quality of natural and chemical properties of oil extracted from tubers, which ranges from 20 to 36%, which may contribute significantly to fill the oil gap in Egypt.