Ahmed A. M. and M. M. A. Kassem( 2008). Cotton response to irrigation intervals under different levels of potassium and nitrogenAssiut J. of Agric. Sci., 39 (5) (171-185)
Abstract: Two field experiments were carried out at Mallawi region, Naway village, Minia governorate, during the two successive seasons of 2006 and 2007 to study the effect of application amount of potassium, 0, 24 and 48 kg k2O/fed, and nitrogen, 60 and 90 kg N/fed, on the response of cotton cultivar Giza 80 to water stress imposed by extending irrigation intervals from every two weeks to be every three week. Results of this study could be summarized as follows:
Irrigation intervals every three weeks resulted in significant reduction in plant height, number of fruiting branches/plant, number of open bolls/plant and seed cotton yield (kentar/fed) in the two studied seasons, and leaves content of K and seed index in 2007 season only. Increasing K amount up to 48 kg K2O/fed significantly increased leaves content of N and K, yield and yield components but significantly decreased lint%, however, the differences were not always significant between the lower K level (24 kg K2O/fed) and the control or between the two amounts of K. Increasing N amount from 60 to 90 kg N/fed significantly increased leaves content of N and K, plant height and number of fruiting branches/plant in both seasons but, it failed to exert any significant effects on yield or yield components except for number of open bolls/plant in 2006 season only. The interaction of irrigation intervals × K amount significantly affected only seed cotton yield and seed index in both seasons when K application increased both traits under longer irrigation intervals greater than under closer ones. The interaction between irrigation intervals and N fertilization exhibited significant effects only on plant height in both seasons and number of fruiting branches/plant in 2007 season only when growth of well-watered plants responded to increasing N amount more favorably than that of water-stressed plants. The interaction of irrigation intervals × K × N or the interaction of K × N exerted no significant effects on all studied characteristics in both seasons. It could be concluded from this study that increasing K amount significantly increased seed cotton yield particularly under water inadequacy conditions otherwise, increasing N amount to 90 kg N/fed failed to significantly increase seed cotton yield at either longer or closer irrigations intervals.
Keywords: (cotton, irrigation intervals, potassium, nitrogen.)
