Ratio effects of barley intercropped with hairy vetch on plant nitrogen content, population and diversity of weeds and yield

In order to study the density and diversity of weeds and yield of barley and hairy vetch affected by mixed intercropping ratios، a field experiment was performed based on a randomized complete block design with four replications at the Agricultural Research Station، College of Agriculture، Ferdowsi University of Mashhad during growing season of 2012-2013. Ratios of mixed intercropping were 75% hairy vetch+25% barley، 50% hairy vetch+50% barley، 25% hairy vetch+75% barley and their monoculture. The results indicated that the effects of mixed intercropping ratios of barley with hairy vetch were significant (p≤0. 01) on density and dry weight of weeds for narrow and broad leaves in two sampling stages، yield components، yield and land equivalent ratio (LER) based on biological and seed yields. The lowest and the highest weed number for the first and the second stages were observed in 75% hairy vetch+25% barley (with six and three species) and barley monoculture (with nine and seven species)، respectively. For the first and the second sampling stages، the highest Shannon-Weiner diversities were calculated in barley monoculture with 0. 96 and 0. 72، respectively. The maximum biological yield، seed yield and dry forage yield of hairy vetch were achieved in its monoculture with 927. 5، 495. 6 and 810. 0 kg. ha-1، respectively. Whereas the highest biological yield and seed yield of barley were obtained in its monoculture with 14780. 9 and 7384. 6 kg. ha-1، respectively. The maximum LER based on biological yield and seed yield were observed in 50% hairy vetch+50%barley with 1. 21 and 1. 20، respectively.