The reaction of grain yield and yield components of wheat (Triticum aestivum L.) varieties in competition with Japanese brome (Bromus japonicus L.) in Sistan region

To determine grain yield and its components of four wheat cultivars in competition with Japanese brome (Bromus japonicus L.), a field experiment was carried out in factorial arrangement using randomized complete blocks design with four replications at the Chah-Nimeh Station, University of Zabol, Iran, in 2014-2015 growing season. The experimental factors were four wheat varieties (Hamoon, Hirmand, Boolani and Kalak Afghani) and weed densities in seven levels of Japanese brome (0, 100, 150, 200, 250, 300 and 400 plants per m2). In this research, grain yield and its related traits including harvest index, biological yield, number of tiller per plant, 1000-grain weight, number of grain per spike, number of fertile tiller per plant and number of spike per m2 were measured. Results of analysis of variance showed that there were the significant differences among wheat varieties and among weed densities for all studied traits and variety × weed density interaction for all studied traits except for harvest index. The results also indicated that reaction of varieties were significantly different in terms of competition with Japanese brome, so that the highest number of tiller, plant height, biological yield and grain yield were obtained from the Kalak Afghani variety and biologic and grain yield of the Japanese brome in competition with this variety was far less than the other varieties. Totally, results of this research revealed that the grain yield more than the biologic yield of wheat varietieswas affected by competition with Japanese brome and interference tolerance index (ITI) of wheat varieties in biologic yield was more than the grain yield.