Effect of carbon dioxide enrichment on yield and yield components of wheat under weed competitive pressure of winter wild oat (Avena ludoviciana L.)

To study the effects of carbon dioxide enrichment on morphological, nutrient absorption and yield of wheat (Triticum aestivum L. cv. Pishtaz) under weed competitive pressure of wild oat (Avena ludovicianaL.), an experiment was conducted as a split plot based on a randomized completely block design during the 2013-2014 growing season at the Research field of Tarbiat Modares University, Iran. Carbon dioxide concentrations (400, 700 and 1000 ppm) and weed densities (0, 25, 50, 75 and 100 plants/m2) were arranged in the main- and sub-plots. Open top chambers were used for CO2 concentration adjustments. Results indicated that, increasing the concentration of carbon dioxide caused an increasing in yield and yield components of wheat. The highest and the lowest yield and yield components were observed in maximum and minimum concentration of carbon dioxide, respectively. Also, increasing in weed density significantly decreased yield and yield components of wheat in all CO2 concentrations. In addition, under all CO2 concentrations, the density of 100 plants per square meter of wild oat compared to control caused decreases in wheat yield and yield components. The value of these decreases were 76.5, 78.26 and 88.80 percent in 400, 700 and 1000 ppm CO2 concentrations, respectively.