Allelopathic effect of Siberian iris (Iris sibirica) on the early growth of wild oat (Avena fatua) and Canada thistle (Cirsium arvense)

Abstract

During 2015 a laboratory and greenhouse experiments were carried out to explore the allelopathic potential of different plant parts of Siberian iris (Iris sibirica) on wild oat (Avena fatua) and Canada thistle (Cirsium arvense) early growth. The aqueous filtrates of Siberian iris rhizomes produced a strong inhibitory effect on germination, radicle and hypocotyl length and seedling weight of wild oat. Contrary, germination, radicle and hypocotyl length of wild oat was not significantly reduced by any Siberian iris leafs filtrate concentrations, but seedling weight of wild oat was significantly reduced at the 1/1 and 3/4 filtrate concentrations of Siberian iris leafs, relative to control. Similar, germination, hypocotyl length and seedling weight of Canada thistle, were significantly affected by the aqueous filtrates of Siberian iris rhizomes, and while same parameters were none significantly reduced by the aqueous leaves filtrates of Siberian iris in compare with the control. In green house experiment, all treatment with different Siberian iris rhizomes residues significantly affected density, height and fresh weight of wild oat plants. Opposite, no one treatment by Siberian iris leaf residues caused significant reduction of plants density, height and fresh weight of the wild oat plants in compare with the control. All Siberian iris mixtures with rhizomes residues highly significant decreased Canada thistle plants density in average for 60.1%, and fresh weight for 60.3% in compare with the control. No one treatment by Siberian iris leaf residues caused significant reduction of plants density and height of Canada thistle, but 1/1 and 1/2 residues mixtures of Siberian iris leaf significantly reduced its fresh weight.