ABSTRACT:

Two field trials were conducted, during 2016 and 2017 wet seasons at the Institute for Agricultural Research (IAR) farm, Samaru (11° 11´ N, 07° 38´ E and 686m above sea level) Ahmadu Bello University, Zaria, in the northern Guinea savannah ecological Zone of Nigeria respectively, to assess the performance of three extraearly maize varieties (SAMMAZ-29, SAMMAZ-32 and SAMMAZ-33). Consisting of 12 weed control treatment combinations and they are as follows: 1.Nicosulfuron(0.075) at 2WAS only, 2. Nicosulfuron (0.075) at 2WAS followed by(fb) hoe weeding at 5WAS, 3. Nicosulfuron (0.075kga.i/ha) at 2WAS fb Nicosulfuron (0.075kga.i/ha) at 5WAS, 4. Nicosulfuron (0.15kga.i/ha) at 2WAS only, 5. Nicosulfuron (0.15kga.i/ha) at 2WAS fb hoe weeding at 5WAS, 6. Nicosulfuron (0.15kga.i/ha) at 2WAS fb Nicosulfuron (0.075kga.i/ha) at 5WAS, 7. Atrazine + Pendimethalin(2.0+2.0kg a.i/ha) only, 8. Atrazine + Pendimethalin (2.0+2.0 kg a.i/ha) fb hoe weeding at 5WAS, 9. Atrazine + Pendimethalin (2.0+2.0 kg a.i/ha) fb Nicosulfuron (0.075kga.i/ha) at 5WAS, 10. Atrazine (2.0 kg a.i/ha) fb Nicosulfuron (0.075kga.i/ha) at 5WAS, 11.Hoe weeding at3 and 6 weeks after sowing(WAS) and 12. Weedy check. The treatments were laid out in a split plot design, weed control in the main plots and varieties in the sub-plot and replicated three times. The parameters measured includes; cob length, cob diameter, number of grains per row, number of kernel rows per cob, 100-grain weight and grain yield (kg/ha). Application of Nicosulfuron(0. 15kga.i/ha) at 2WAS followed by Nicosulfuron(0. 075kga.i/ha) at 5WAS gave significantly higher cob length, cob diameter, -1 number of grains per cob, number of grain-rows per cob, 100-seed weight and grain yield ha than other weed control treatment combinations. In conclusion, it could be suggested that Nicosulfuron(0. 15kga.i/ha) at 2WAS followed by Nicosulfuron (0. 075kga.i/ha) at 5WAS (W6) could be used by farmersin the Northern Guinea savannah ecological zone of Nigeria.