phytotoxicity effects of soil amended residues of wild barley (hordeum spontaneum koch) on growth and yield of wheat (triticum aestivum l.)

wheat (triticum aestivum) growth and yield are depressed by physical and chemical interference of weeds. recently, wild barley (hordeum spontaneum) population has increased in wheat fields of many provinces of iran. since, little is known about the allelopathic effects of wild barley residues in soil, greenhouse studies were conducted to examine the effects of soil amended residues of wild barley at 0, 0.2, 0.4, 0.8, and 1.6 kg m-3, and its root exudates on growth and yield of wheat. there were no significant differences in wheat seedling height and fw when exposed to 0.2 and 0.4 kg m-3 , whereas, the two high residue levels, i. e., 0.8 and 1.6 kg m-3 significantly reduced these parameters. two high residue levels also significantly reduced seedling and mature plant height fresh and dry weights, and yield of wheat. root exudates that released from wild barley seedlings into the soil, did not affect wheat seedling height, whereas, those released from tillers significantly decreased seedlings and mature plants heights, fw and dw and yield of wheat. key words: allelopathy; soil amended residues; wild barley; hordeum spontaneum; wheat growth; yield