investigating Status the weeds in direct seeding of the spring

To investigating the density of weeds in direct seeding wheat in the corn straws (no tillage wheat), a split factorial experiment was carried out in randomized complete block design with four replications and three factors including cultivar at 2 levels, (Chamran and Behrang), seed density at 5 levels (50, 100, 150, 200 and 250 Kg/ha) and nitrogen fertilizer from urea source at 6 levels (0, 50, 100, 150, 200 and 250) in fall of 2011 – 2012 in an agricultural farm located 30 km south of Dezful. The result of analysis of variance revealed that the effects of cultivar, seeding and nitrogen fertilizer on weed density and dry weight of weeds and yield and grain yield components were significantly different at 1% level. The least weed density was observed at 250 Kg/ha, with one weed per square meter. Results showed that greater consumption of nitrogen fertilizer will increase the dry weight of weeds per area unit, so that the fertilizer level of 250 kg nitrogen per hectare with an average of 9.9 grams in the square meter had the highest dry weight of weeds per area unit. The no tillage seeding caused increasing the grassy weeds. Using seeds over 100 Kg/ha which decreases yield grain and increases nitrogen consumption to the level 150 (Kg/ha) resulted in significant increase in grain yield. Chamran cultivar, with grain yield average of 413.70 (kg/ha) was preferd to Behrang cultivar.