اثر رقابت علف هرز يولاف وحشي (.Avena ludoviciana L) بر عملكرد و اجزا عملكرد دو رقم گندم (.Triticum aestivum L) با قدرت متفاوت رقابت

Competition effect of wild oat {Avena ludoviciana L.) on two wheat (Triticum aestivum L.) genotypes contrasting in their competitive ability

To investigate the effects of wild oat competition on yield and yield components of two contrasting winter wheat cultivars, an experiment was conducted at the Research Station of Plant, Pest and Disease Institute of Karaj, during 2003-2004 growing season with a factorial arrangement of treatments in a randomized complete block design with 4 replications. Experimental factors were wheat varieties (Rooshan (as less competitive) and Niknejad (as more competitive)) 3 wheat densities ((optimum, 1.25 and 1.50 folds of optimum (300, 375 and 450 plants m-2for Rooshan and 400, 500 and 600 plants m"2 for Niknejad)) and 4 wild oat densities (0, 25, 50, and 75 plants m-2). Results indicated, maximum yield of two cultivars were archived in optimum plant density on weed free condition. At presence of wild oat, the maximum grain yield of Niknejad and Rooshan were achieved at its 1.25 fold optimum and optimum wheat density, respectively. As wheat density increased, height, spike m-2 and number of seed m-2 increased and number of tiller per plant decreased. The presence of wild oat in wheat reduced grain yield, above ground biomass, number of tiller of wheat and number of spike m-2, and the magnitude of this reduction was dependent on weed density of wild oat.