الفهرس 
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Abstract
Two field experiments were carried out at the Farm in El-Zarka Center, Damietta Governorate, during the two successive summer seasons of 2008 and 2009 to study the effect of plant spacings and combined application of mineral and organic nitrogen fertilization on growth, yield and its components of two rice cultivars namely Egyptian hybrid rice 1 (H1) and local cultivar (Giza 178). Each cultivar (H1 and Giza 178) was practiced in a separate experiment. Every experiment was carried out in strip plot design with three replications. The vertical plots were occupied with plant densities reporting three hill spacings as follows: D1- 15 × 15 cm (552000 plants/fed). D2- 20 × 20 cm (306000 plants/fed). D3- 25 × 25 cm (201600 plants/fed). The horizontal plots were assigned to the combinations of nitrogen fertilizer levels together with organic manure treatments as follows: 1. 100 % mineral nitrogen (70 kg/fed). 2. 75 % mineral nitrogen (52.5 kg/fed) + 25 % organic nitrogen (17.5 kg/fed). 3. 50 % mineral nitrogen (35 kg/fed)+ 50 % organic nitrogen (35 kg/fed). 4. 25 % mineral nitrogen (17.5 kg/fed) + 75 % organic nitrogen (52.5 kg/fed). 5. 100 % organic nitrogen (70 kg/fed). STUDIED CHARACTERS: A. Growth characters: 1- Number of days from planting to 50 % heading. 2- Flag leaf area (cm2). B. Yield and its components: 3- Plant height (cm). 4- Number of panicles/m2. 5- Panicle length (cm). 6- Number of grains/panicle. 7- Grains weight/panicle (g). 8- 1000- grain weight (g). 9- Grain yield (t/fed). 10- Straw yield (t/fed).