الفهرس 
Effect of nitrogen sourcesOnly 14 pages are availabe for public view
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Abstract
The main objective of this work was to improve the production and quality of potato crop in Gharbiea governorate. The field experiments were conducted at a farm in EL Mehalla EL Koubra during the summer seasons of 1993~3~1994 The study included two parts and every part was carried out throughout two summer seasons . The first part was to study the effect of some nitrogen levels and sources on growth, tubers yield and quality and chemical constituents . Nitrogen was supplied from three sources such as urea ( 46% N ), ammonium nitrate ( 33.5 ?4 N ) and ammonium sulphate ( 20.5 % N ). Each fertilizer was applied either alone or followcd by each of the others at three levels ( 60,90 and 120 kg Nlfed. ) The second part was to study the effect of sulphur ( 0 and 50 kg/fed. ) and some nitrogen sources on growth, tubers yield, tubers quality and chemical constituents. The experiments were designed as a split plot with four replications and the cultivar used was Cara certificate in two parts. The results are summerized as follows :- Port I:- Effect of nitrogen levels and sources :- A-Effect of nitrogen levels :- 1 - Vegetative gro wtlz :- -The nitrogen level had no significant effect on stem length , main stems number, whole branches number ,leaves number and leaf area in both seasons .However, leaves dry weight percentage was significantly increased by applying the rates of 60 or 90 kg I fed in the second season only. 2- Yield :- -Total tubers numberlplant, tubers number of grades C and D were not significantly affected by nitrogen levels in both seasons. However, total tubers weightlglant, tubers weight and number of grade A and their percentages were significantly increased by applying the rate of 90 kg N I fed. Moreover, the tuber number of grade B and its percentage were significantly incrcased by fertilization of 120 kg Nlfed in the second season only. Furthermore, tubers number and weight of grades C and D and their percentages were significantly increased by application of 60 kg Nlfed. in the second season. 3- Qunlitv :- -Specific gravity and starch content of tubers were significantly increased by applying 60 kg N/fed. in the first season only .