Abstract:
A field experiment was conducted in 2011/2012 and 2012/2013at the Demonstration Farm, Faculty of Agriculture, University of Khartoum to investigate the response of maize plants to nitrogen fertilizer levels and weeding time.Treatments were assembled in a randomized complete block design with split plot arrangement replicated four times. Two levels of nitrogen 0N (zero nitrogen) and 2N (80 lbs/fed inurea form) were assigned to the main plots. Eight weed removal timesat 15, 30, 45, 15+30, 15+45, 15+30+45,days after sowing ( DAS), weedy and weed free treatmentswere assigned to the sub plots. The results showed thatunrestricted weed growth reduced maize height by 48.9 and 38.4%, shoot dry weight by 74.9 and 73.8% and final yield (ton/ha) by 86.5 and 83.7% in 2011/2012 and 2012/2013 seasons, respectively. Delaying weed removal for 45 DAS decreased plant height by 25.1, 19.9%, and shoot dry weight by 72.1 and 63.8% in 2011/2012 and 2012/2013 seasons and attained yield components cob length, cob weight, grain number/plant, grain weight/plant and final yield (ton/ha) comparable to the weedy check. Nitrogen at 80 lbs/fed increased maize height by 33.1% and 29% ,shoot dry weight by 39.8 % and 55.5% andFinal yield ton/haby 43.5 and 42.7 % in 2011/2012 and 2012/2013 seasons. The interaction between N rates and weed control times had significant effects on maize height, shoot plant dry weight, cob length, cob weight, grain number/plant, grain weight/plant and final yield (ton/ha.) 2N + weeding at 15 + 30 + 45 DAS resulted in plant height comparable to the weed free treatment, and increased yield by 91 and 85.8 % in 2011/2012 and 2012/2013, respectively
