Inhibiting Effects Of Siam Weed (Chromolaena Odorata (L.) King & Robinson) On Seed Germination And Seedling Growth Of Four Crops

Siam weed (Chromolaena odorata (L.) King & Robinson) usually grows in plantations, agricultural fields, pasture lands, wastelands and roadsides, where it leaves a lot of plant residues that are used either directly to crop fields for composting or for compost preparation. Authors hypothesized that plant debris of siam weed in the field soil might be detrimental to seedling emergence of crop species. The aqueous extracts of siam weed was tested on seed germination and seedling growth of four field crops namely, rice (Oryza sativa), groundnut (Arachis hypogea), chickpea (Cicer arientinum) and mustard (Brassica campestris). The effects of various plant parts of the weed (leaf, stem and root) at different concentrations (2.5, 3.5 and 4.0%) of the extracts on seed germination, patterns of root and shoot growth, and dry matter accumulation of selected crops were determined in a laboratory bioassay. Results revealed that all crops were significantly reduced in their growth by the allelopathic effects of the weed, average percent inhibition (API) ranged from 13.36 to 24.72%. Groundnut and rice were the mostly affected crops with 24.7% inhibition. Among the plant parts, leaf was most inhibitory (API = 24.39%) and the least effect was noticed by stem extract (API =
17.20%). The inhibitory effects were concentration dependent. A 4.0% extract of siam weed leaf extract was
enough to reduce the growth of the crops by about 42%. Therefore, the presence of siam weed in crop field or
incorporation of leaves of siam weed in the fields must be avoided.