Allelopathic effects of rapeseed residue on germination and seedling growth of redroot pigweed {Amaranthus retroflexus)

摘要

In order to study allelopathic effects of rapeseed residue on germination and growth of redroot pigweed (Amaranthus retroflexus), laboratory and greenhouse experiments were carried out at the Research Station of Islamic Azad University, Tabriz Branch,Iran. Studied factors in the experiment were rapeseed variety (Hyola, a local variety and Sarigol, an improved variety), growth stage of rapeseed (stem elongation, flowering and maturity) and aqueous extract of rapeseed (root, aboveground part, root+aboveground parts.distilled water as control). Results revealed that redroot pigweed germination was inhibited by extract of aboveground and root+aboveground parts of rapeseed. In both cultivars, extract from maturing and flowering stages of rapeseed decreased more effectively dry weight than extract of plants at stem elongation stage. Seedlings treated with extract from maturing and flowering growth stages caused reduction of 85% and 54% in seedling vigor index (SVI) in comparison to control. Treatment ofpigweed seeds with rapeseed residue harvested at stem elongation stage had similar specific leaf area (SLA) as control. Aboveground parts extract had highest effect on leaf weight ratio. This result was not unexpected. Rapeseed residue, especially of Hyola cultivar, can play a major role in controlling of redroot pigweed.