Author(s): M. AMEENA AND V.L GEETHAKUMARI

Abstract: Selection of allelopathic plants is a commonlyrnused approach to identify plants with biologically active natural products.rnLaboratory experiments were conducted to determine the allelopathic effects ofrnpurple nutsedge (Cyperus rotundus L.) extracts on common upland weeds of Keralarnlike Chromolaena odorata (L.), Synedrella nodiflora and Gomphrena decumbensrnwith a view to explore its weed seed inhibition potential. Aqueous nutsedgernextracts inhibited germination and growth of Gomphrena decumbens while it hadrnno significant influence on the germination of other two weed seeds. InrnGomphrena, nutsedge extracts taken after flowering caused greater growthrninhibition compared to extract taken before flowering indicating differentialrninhibition at various growth stages of nutsedge as well as increasedrnallelochemical production after flowering stage. Suppression of plumule growthrnand significant reduction in radicle growth and vigour index was observed forrnall the three weed seeds tested. The study revealed greater inhibition rate forrnextracts collected after flowering, which indicated that allelochemicalrnproduction is more after flowering. The tuber extracts ofrnnutsedge as identified by HPLC technique revealed the presence of phenolicrncompounds viz. p-hydroxybenzoic acid and p-coumaric acid.

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