Growth Response of Winter Wheat (Triticum aestivum L.) and Wild Barley (Hordeum spontaneum Koch) to Nitrogen

A greenhouse study was conducted to investigate the effects of nitrogen (N) on wild barley (Hordeum spontaneum Koch) interference with winter wheat (Triticum aestivum var. Pishtaz) by an additive series experiment. The experiment was conducted in a split plot design with 3 replications. Wheat plant height losses were on average 30, 10, and 10% in a wild barley density of 16 plants per pot with an N supply of 40, 80, and 160 mg per kgsoil, respectively. At all N application rates, wheat tillers decreased in the presence of wild barley densities of 4, 8, and 16 plants per pot. Increased N stimulated wheat tiller growth per plant but this effect was reduced by wild barley interference. The highest leaf area was observed at 80 mg N per kg soil for both species in monocultures. Significant differences were observed among wheat dry weight values in all wild barley densities and at each level of N application rate. Shoot N concentration of wild barley was greater than that of wheat. Wild barley competition always reduced shoot N concentration of wheat and this was increased with increasing wild barley density. The results of this study suggested that wild barley is more responsive to soil N levels than wheat.