Effect of Chromolaena odoratum Aqueous Extract on Bioassay Plant and its Soil Incorporation for Weed Suppression in Paddy Field

Abstract

This study was aimed to investigate an effect of Chromolaena odoratum (L.) R.M. King & H. Rob extract on weed test, and its soil incorporation for paddy weed suppression. Aqueous extract of whole C. odoratum plant at concentrations of 0 (control; distilled water), 12.5, 25, 50 and 100 g dry weight/L was bioassayed (in vitro) on the germination and seedling growth of barnyardgrass (Echinochloa crus-galli (L.)
Beauv.) and false daisy (Eclipta prostrata L.) weeds by petri-dish test method. The result showed that whole plant extract at all concentrations significantly deceased the germination, shoot and root length of both weeds except at concentration of 12.5 g/L.
Results indicated that increase of C. odoratum concentration causes the progressive inhibitory. Fresh whole plant cooperated with paddy soil in plastic pot condition at ratio of 1.6, 3.2, 4.8 and 6.4 ton fresh weight/rai suppressed total weeds by 77.5,
81.95, 85.7 and 87.22%, respectively. All rates used completely inhibited broadleaf and sedge weeds (100%). These results suggested C. odoratum had inhibiting compounds, called allelochemicals, that can inhibit the germination and seedling growth of certain paddy weeds. It could be applied for weed control in rice production in order to decrease or success uses of synthetic herbicide in the future.