Allelopathic assessment of common amaranth by ECAM

ABSTRACT: A laboratory-based study was carried out as factorial experiment based on randomized complete block design with four replications in 2011-2012 to investigate the allelopathic effects of common amaranth (Amaranthus retroflexus L.) root exudates on seedling growth of common bean (Phaseolus vulgaris L.). Three factors were consisted of common bean cultivars including Naz, Derakhshan, Sayyad, Shokufa, Dehgan and Sadri, common amaranth density at six levels as 0, 4, 8, 16, 24 and 32 plants /beaker and agar medium at three levels as 0, 2 and 4% of activated charcoal. The equal-compartment-agar-method (ECAM) was able to evaluate the allelopathic effects. Reduction in growth of common bean cultivars was intensified by increasing the common amaranth density in agar medium and the density of 24 plants per beaker had the highest inhibitory effect on common bean and decreased shoot height, total root length, shoot and root dry weight, significantly, while all of these attributes were increased by adding the activated charcoal to the agar medium. The medium with 4% of activated charcoal significantly increased the common bean growth as compared with 0 and 2% of activated charcoal. The common bean cultivars showed different responses to allelopathic effect of common amaranth.