Determination of the proper time and application amount of Atrazine herbicide in weed control in grain corn and effects of its residue on wheat germination

An experiment was conducted to determine the proper time and Atrazine dose for control of weeds in grain corn. The experiment was conducted at the University of Shiraz Agricultural Experimental Station. Experiment was in a randomized complete block design with factorial arrangement of treatments. The treatments were application time (pre-planting, 10, 20, 30 and 40 days after corn emergence) and herbicide dose (0, 0.7, 1, 1.4 and 2.1 Kga.i./ha). The carry over effects of Atrazine residues on wheat emergence were also evaluated. The experiment results showed that only corn grain number was affected by the time of application. Herbicide dose had significant effect on grain weight. Both application time and herbicide doses significantly affected dry weight of weeds. Later use of herbicide had no effect on dry weight of weeds. Due to good control of weeds by herbicide at 2.1 kg/ha, the grain yield increased significantly when compared with weedy check. Results also indicated that rate of herbicide had more effect on wheat germination percentage compared with application time. Minimum and maximum germination percentage were at 2.1 Kg/ha and control treatments respectively.