Effects of Time of Spraying and Competitive Ability of Wheat Cultivars in Weed Control

In order to investigate the effect of competitive ability of wheat cultivars with weeds in the Kurdistan region, an experiment was conducted in Agricultural Research Station Qamlv. A split plot design based on a randomized complete block with four replicates was used in growing season of 2004-2005. Main plots consisted of four cultivars of wheat (Alvand, Zarin, Back cross Roshan and Shahriar) and sub-plot consisted of four levels of herbicides 2.4.D application time (early spring spraying (2 to 3 leaves), spraying in mid-spring (complete tillering), late spring (grain dough) and non pesticides application) were compared in combination with one another. Factores in this experiment are include: weed dry weight, plant height, stubble yield, biological yield, number of ear per unit area, number of grains per ear, grain weight, grain yield and harvest index. Results of comparison of data showed that the highest plant height, biological yield, number of ear per unit area, number of grains per ear, grain yield and harvest index relevant to Back cross roshan, it showed competitive ability towards weeds in comparison with other cultivars. In this experiment, spraying in mid-spring with 1250 kg per hectare, was known as the effective time of spraying to eliminate the competition with weeds and the back cross Roshan as the best cultivar to competition with weed.