ALLELOPATHY OF VELVET BEAN (Mucuna cochinchinensis (Wight) Burck) EXUDATES AND ITS INHIBITORY EFFECTS ON WEEDY RICE (Oryza sativa L.)

The experiment was conducted at the Toxicology laboratory, Faculty of Agriculture, University Putra Malaysia, Serdang, Malaysia in 2013. Allelopathic potential of aqueous methanol and water extracts of Mucuna. cochinchinensis leaves, seeds and roots were investigated on seed germination and seedlings growth of weedy rice (Oryza sativa); and biotest crop specie: lettuce (Lactuca sativa). The treatments consisted of five concentrations (100, 75, 50, 25, 0 %); plant parts (leaves, seed, root) and extraction solvents (methanol, water) were replicated three times and arranged as a completely randomized block (CRD) design. Germination, hypocotyl and radicle growth of all test plant species were inhibited at concentrations (100, 75, 50 and 25%). Inhibitory activity was dependent on the extraction solvents and extract concentrations as reported that methanol at higher extract concentration had the stronger inhibitory activity. The mean EC50 values of M. cochinchinensis leaves, seed and root of methanol extracts in relation to the germination inhibition of O. sativa, 86.06%, 416.32% and 72% respectively, and 30.66% 55.84% and 18.24%, respectively, in Lactuca sativa. Similar trend was observed with the varying concentration of the water extracts. The methanol extract of root showed a greater inhibitory effect on the hypocotyl and radicle growth of weedy rice than its water extract, and more effective on total germination.