Study of Canopy Structure and Growth Characters Role of Two Wheat Cultivars in Competition, on Economic Threshold and Yield of Rye and Wild Mustard

To evaluate the role of effective factors on competition of two wheat cultivars against two species of narrow leaf and broad leaf weeds this study was conducted as two separated experiments based on a randomized complete block design with 3 replications at Agricultural Faculty of Bu-Ali Sina University, in 2008-2009. In both Experiments, Alvand and Sayson cultivars were planted with densities of 450 plants m-2. In the 1st experiment, rye with densities of 0, 20, 40, 60 and 80 plants m-2 were planted in inter-rows of wheat. In the 2nd experiment, wild mustard densities were 0, 8, 16, 24 and 32 plants m-2. The results showed that characters such as vertical distribution of leaf area index and dry matter, height and its increase rate in interference, emergence rate, rate of canopy development and precocity led to increasing competitive ability of Alvand than Sayson in competition with two weed species. These factors were effective in reduction seed production of weeds and economic threshold in Alvand. Despite of lower height of wild mustard than rye, distribution of leaf area and canopy structure of wild mustard increased light competition ability and shadow on crop, so that harmful effects of individual plant of wild mustard in different densities was more than rye. Increasing rate of wild mustard seed bank was more than ray