RESPONSE OF GROWTH, YIELD AND ITS COMPONENTS AND MICROENVIRONMENTAL FACTORS OF COTTON PLANT TO NITROGEN FERTILIZER LEVELS, PLANT DISTRIBUTION AND DENSITIES

Two field experiments were conducted during summer seasons of 2006 and 2007. The aim of this investigation was to study the effect of relationship among nitrogen level and plant distribution with growth, yield and its components and micro environmental factors in cotton fields.
Twelve treatments which were the combination of three plant densities and distribution of cotton cv.80 i.e 45000, 60000 and 75000 plants /fed. were resulted from inter ridge widths (80, 40 and 60 cm) within ridge spacing (20, 15 and 15 cm) and (two, one and two plants/hill) respectively. And four nitrogen levels (55, 70, 85 and 100 kg N/fed.) were assigned in split-plot design with four replication. Environmental characters were determined at 70, 100, 130 and 160 days from sowing.
                The data revealed that plant length and the number of leaves/plant were significantly increased by increasing nitrogen levels from 55 to 100 kg N/fed. The rate of increased was higher at the addition of 100 kg N/fed. as compared with other nitrogen rates. Increase nitrogen levels decreasing boll weight and cotton yield/fed. As the nitrogen rates increased, the light penetration was significantly decreased as the lower third of plant, the air canopy, leaf and soil temperature were tended to decrease. Also the relative humidity (R.H) in cotton canopy tended to increase by increasing nitrogen fertilizer rates. This was true at the different stages of growth (i.e. 70, 100, 150 and 160 days from sowing)during the two successive seasons of 2006 and 2007. By increasing the plant density from 45000 to 75000 plants per feddan., length plants were increased, but the number of leaves and fruiting branches/plant was decreased significantly. Boll weight and seed cotton yield/plant and feddan increased by decreasing plant density from 75 to 45 thousand plants/fed. in both seasons. As the plant density per unit area increased the light penetration was significantly decreased. The decrease was greater at the lower third as compared with that mid plant. also increasing plant density, the air canopy, leaf and soil temperature (⁰c) were decreased at 70, 100, 130 and 160 days after sowing in both seasons, the relative humidity tended to increase by increasing the plant density from 45000 to 75000 plants/fed.
All the interaction between plant density and distribution and nitrogen levels on growth, micro environmental factors in cotton field at different stage of growth i.e 70, 100, 130 and 160 days after sowing and yield and its components in this investigation did not reach the 5% level of significance.