Abstract

In order to study the effects of the application of various amounts of nitrogen fertilizers and Pix 35% growth regulator on the morphological features of the Sahel cultivar of cotton (Gossypium hirsutum L.), and on the unginned cotton yield of this cultivar, an experiment was carried out in the factorial design in the randomized complete block format with three replications at the Bayekola Agronomical Research Station in 2009. The factors studied included the amounts of nitrogen fertilizers and of the cotton growth regulator Pix 35% used in the experiment. Results obtained showed that the minimum plant height was obtained in the control treatment (72.93 cm), and that plant height increased with nitrogen application and reached its maximum (77.59 cm) when 225 Kg.h of nitrogen was used. The analysis of the variance of the data indicated that the effects of applying various levels of Pix were very significantly different, so that the greatest plant height was observed in the Pix control treatment (90.94 cm), and it significantly decreased by Pix application and reached 65 cm when 300 g.h of Pix was applied (which was an almost 40% reduction). Furthermore, when nitrogen fertilizers were applied, the unginned cotton yield significantly went up, and this increase in yield continued up to the level of using 150 Kg. h nitrogen; however, when the level of nitrogen application reached 225 Kg.h, the yield started to go down. As a whole, the lowest yield was obtained when nitrogen was not applied (which was the control with a yield of 1469 Kg of unginned cotton per hectare), and the maximum yield (2825 Kg.h of unginned cotton per hectare) was achieved when 150 Kg of nitrogen per hectare was used _ i.e., the unginned cotton yield went up by 14% when 150 Kg of nitrogen per hectare was applied. In our study, it was observed that Pix did not have much influence on increasing yield: the minimum yield (2529 Kg of unginned cotton per hectare) was observed in the treatment of applying 100 g. h of Pix, and the maximum yield (2669 Kg of unginned cotton per hectare) by using 200 gh of Pix. Comparison of the interaction effects of the level of Pix and nitrogen application indicated that, among all the treatments, the maximum yield of unginned cotton (3010 K.h) was achieved when 150 Kg. h of nitrogen and 200 g.h Pix were applied. These results also showed that in the treatments of using 150 Kg nitrogen per hectare, and applying 150 Kg. nitrogen plus 300 g Pix per hectare also, high yield potentials (close to 3 tons per hectare) were created. The minimum yield of unginned cotton (2230 Kg.h) belonged to the treatment of using 200 grams of Pix per hectare.

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