الفهرس 
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Abstract
Three field experiments were conducted in extension field at Shobrahour village, El- Sinbelaween center, Dakahlia Region, during two successive summer seasons of 1999 and 2000 to study the effect of planting dates, hill spacings, nitrogen fertilizer levels and their interaction on growth, yield, yield components and fiber properties of Egyptian cotton variety Giza 85. The studied factors were: A.Planting dates: three planting dates were studied at: A1= 20th March. A2= 30th March. A3= 10th April. B. Hill spacings: three hill spacing were studied as follow: B1= 25 cm between hills with two plants per hill. B2= 20 cm between hills with two plants per hill. B3= 15 cm between hills with two plants per hill. C. Nitrogen fertilizer levels: Three nitrogen levels were studied at: C1= 30 kg N / fed. C2= 45 kg N / fed. C3= 60 kg N / fed. Studied characters: A- Growth characteristics: 1- Number of days from sowing to first flower opening. 2- Number of days from sowing to first boll opening. 3- Number of fruiting branches per plant. 4-Plant height (cm). B- Yield and its components: 5- Number of open bolls per plant. 6- Boll weight (gm). 7- Seed cotton yield per plant (gm). 8- Seed cotton yield in Kentar/fed. C- Technological properties of cotton fiber: 9- Lint percentage. 10- Fiber length at 2.5%. 11- Fiber fineness (micronaire value). 12- Fiber strength (gm / tex). The most important findings could be summarized as follows: A-Effect of sowing dates: Over both seasons, sowing dates significantly affected all characters under study except lint percentage, span length at 2.5% and fiber strength. Early sowing (20th March) recorded the highest means of characters, while the lowest value were obtained with dealing sowing to 10th April. Combined analysis showed that maximum number of days from sowing to first flower opening (102.0 days), number of days from sowing to first boll opening (154.4 days), number of fruiting branches per plant (8.2), plant height (123.8 cm), number of open bolls per plant (13.1), boll weight (1.86 gm), seed cotton yield/plant (22.8 gm), seed cotton yield (8.734 Kentar/fed) and micronaire value (3.10). On the contrast, minimum values were obtained with delaying sowing date (10thApril). Meanwhile, micronaire value was not significantly affected by sowing dates in 2000 season. Over both seasons, seed cotton yield/fed was significantly decreased gradually due to delaying sowing date since seed cotton yields averaged 8.734, 7.164 and 6.492 Kentar/fed due to sowing dates of 20th March to 30th March and 10th April, respectively. B- Effect of hill spacings: Hill spacings had significant effect on all the studied characters except lint percentage and fiber strength. Over both seasons, sowing cotton on one side of ridges, 60 cm apart and 25 cm between hills with two plants per hill, recorded the highest mean of number of fruiting branches per plant (7.5), plant height (123.2 cm) and boll weight (1.78 gm). Meanwhile it recorded the shortest period from sowing to first flower opening (96.4 days) and to first boll opening (149.6 days), the lowest seed cotton yield/fed (6.831Kentar/fed), span length at 2.5% (28.25) and micronaire value (3.00). On the contrast, sowing cotton plants on one side of ridge, 60 cm apart and 20 cm between hills with two plants per hill recorded the highest mean number of open bolls/plant (13.0), seed cotton yield/plant (21.6gm) and seed cotton yield (8.817 Kentar/fed). Meanwhile, sowing cotton on one side of ridge, 60 cm apart and 15 cm between hills with two plants per hill recorded the highest period from sowing to first flower opening (99.8 days) and to first boll opening (150.8 days), span length at 2.5% (28.40) and micronaire value (3.10). On the contrast, this treatment led to the lowest mean number of fruiting branches per plant (6.7), plant height (120.2cm), mean number of open bolls/plant (11.1), boll weight (1.78 gm), seed cotton yield/plant (15.2gm). Over both seasons, seed cotton yield/fed was 7.192, 8.817 and 6.381 Kentar/fed with hill spacings of 15 cm, 20cm and 25cm, respectively. C- Effect of nitrogen fertilizer levels: Nitrogen fertilizer levels had marked effects on all estimated characteristics in both seasons. Incremental doses of nitrogen caused marked increases in most of the studied traits. Adding 60 kg N/fed was associated with the maximum mean number of days to the first flower opening (99.1 days) and boll opening (150.3 days), mean number of fruiting branches/plant (7.7), plant height (123.1cm), mean number of open bolls/plant (12.9), boll weight (1.79 gm), seed cotton yield/plant (21.0 gm) and seed cotton yield (8.073Kentar/fed). On the contrast, this level as nitrogen fertilization resulted in the lowest span length at 2.5% (28.26). On the other hand N-level of 30 kg N/fed caused the decrease in mean number of days to the first flower opening (97.2 days), mean number of days to the first boll opening (149 days), mean number of fruiting branches/plant (6.6), plant height (120.6 cm), mean number of open bolls/plant (11.5), average boll weight (1.69 gm), seed cotton yield/plant (17.9 gm) and seed cotton yield per fed (6.903Kentar/fed). On the contrast recorded the height of span length at 2.5% (28.44) was increased due to this level of N application. Meanwhile, the differences in lint percentage, micronaire value and fiber strength did not significantly differ with increasing nitrogen fertilizer levels from 30 to 60 kg/fed. Over both seasons, seed cotton yield/fed was 6.903, 7.424 and 8.073 Kentar/fed due to N fertilization at the rate of 30kg/fed, 45kg/fed and 60kg/fed respectively. D- Effect of the interactions: The interaction between sowing dates and hill spacings had significant effects on most of the studied characters. Early sowing date of 20th March and 25 cm between hills resulted in the highest means of number of fruiting branches/plant, plant height (cm) and span length at 2.5%. On other side, sowing cotton plants on 20th March and 20 cm between hills recorded the highest led to mean number of open bolls/plant, boll weight (gm), and seed cotton yield (Kentar/fed).