A field trial was conducted at the experimental farm, Department of Field Crop Science, College of Agriculture, University of Baghdad, Abu-Ghraib in 2001/2002 and 2002/2003 seasons to investigated the effect of seeding rate (120, 180 and 240 kg.ha2), nitrogen levels ( 240, 300 and 360 N kg.ha-2) and rate application of herbicides (Topic 250 gm a.i ha-1+ Logran 125 gm a.i ha-1 and Topic 500 gm+ Logran 250 gm a.i ha-1).
A randomized complete plot design (RCBD) according to split – split plot was used with three replications.
The following results could be summarized as follow :
Rate seeding 240 kg.ha-1 gave a high value of leaf area index (6.1 and 6.9) dry weight of crop (509.6 and 670.4 gm.m-2), rate growth of crop (41.0 and 46.0 gm.m-2.day-1) and net assimilation rate (5.7, 6.0 gm.m-2.day-1)in the two seasons respectively.
In both seasons 2001/2002 and 2002/2003 and at all stage growth of plant especially at stage 102 day from date planting. The high level of nitrogen fertilization 360 kg.ha-1 caused increasing of most characteristic as leaf area index, dry weight of plant, rate growh of crop and net assimilation rate.
The treatment recommendation of Topic and Logran at first season gave high value of leaf area index (6.1) and rate growth of crop (41.9 gm.m-2 day) at second season.
The treatment of full recommendation of rate application of Topic and Logran gave high value of leaf area index (7.5) and dry weight of plant (484.4 gm.m-2.day-1). Rate of seeding 240 kg.ha-1 with 360 kg.N.ha 1 gave in both seasons high value of leaf area index 6.6, 7.2 dry weight of crop (699.2, 597.2 gm.m-2) and rate growth of crop (43.7 and 47.7 gm.m-2.day-1) respectively.The treatment recommendation of Topic and Logran with nitrogen fertilization 360 kg N.ha-1 at first season gave high value of leaf area index 6.6 but at second season gave full recommendation high value 8.0.
From these results we can conclusion that the wheat is positive response to study factors, so we can use competition method to control a weed, instead of herbicide in order to keep clean environment.