Allelopathic effects of sorghum extracts on Amaranthus retroflexus seed germination and growth

摘要

With regards to importance and abundance of Amaranthus retroflexus weed in fields an experiment was conducted using CRD based factorial design with three replications to study the allelopathic effects of sorghum extracts on germination and growth of Amaranthus retroflexus in 2008-2009. Treatments were: harvesting stage of extracted sorghum (vegetative, flowering and seed filling stage), extracted plant part (leaf, stem, root and total plant) and concentration of extract (5, 10, 15 and 20%). Analysis of variance at germination stage of Amaranthus showed that main and interaction effects were significant on all attributes. Using extracts decreased germination percentage and its aspects. Leaf extracts of all vegetative stages had highest decreasing effect. Germination was prevented by 20% extracts of all parts and stages. Compared to control, minimum growth, seedling dry weight, germination percent and germination rate were 49.06, 68.92, 59.44 and 67.31 %, respectively. The main and interaction effects were significant in greenhouse experiment. All attributes decreased with increase of extract concentration from 5 to 20% in all stages. Leaf extract and stem extract had the most and least impact on Amaranthus seed germination. Compared to control, sorghum extract treatment decreased height, leaf area and number, leaf, shoot and root dry weight and biomass 50.40, 54 20, 57.71, 77.48, 73.0, 64.51 and 72.35%, respectively. Sorghum allelopathic ability can be used for decreasing plant population of pigweed and preventing more use of herbicides.