Studying competitive effect of Asian spider flower on changes in growth indices, yield and components yield of soybean and seed production potential of this weed in field condition

In order to investigate the soybean competitive ability (DPX cultivar) under interference condition different densities of Asian spider flower (0, 3, 5, 10, 15, 20, 30, 45 plant/m-2); an experiment was conducted based on randomized complete blocks design with three replications in 2015–2016 growing season in Kalaleh, Golestan province. Different densities of Asian spider flower had a significant effect on biological yield, economic yield, 100 grain weight and pods per plant of soybean. The highest grain and biological yields of soybean were 374.9 and 734.30 g/m2, respectively which observed in weed-free treatment. However, these traits declined nonlinearly as weed density increased, so that in 45 plant/m-2interference treatment, economic and biological yields reached 172 and 344.38 g/m2, respectively.