Abstract:
The use of rice (Oryza sativa L.) allelopathy for weed management could reduce the need for applying herbicides
to the crop. In this study a pot experiment and a laboratory bioassay were conducted to assess the allelopathic
potential of residues of 30 traditional rice varieties in Sri Lanka on seed germination and seedling growth of
barnyardgrass (Echinochloa crus-galli). All seeds were collected from “Farmer Federation for Conservation of
Traditional Seeds and Agri-Resources”. Rice residues were incorporated with silica sand (1% w/w) in small pots
to prepare residue mixture and ground rice residues mixed with water (2.5g/100ml) were used to prepare residue
extract for laboratory bioassay. Rice varieties exhibited marked differences in the inhibition of barnyardgrass
growth and development. In the bioassay, residue extract of rice variety Herathbanda exhibited the greatest activity on the weed seedling growth, reducing dry weight by 30.7%, while Gonabaru residue extract exhibited the
greatest inhibition on seed germination, reducing germination by 29.6%. In the pot experiment of residue mixture, Batapola el and Sula varieties showed the greatest inhibition percentage on germination (48.4%). However,
Godaheenati showed the greatest inhibition % on plant height (27.4%) and dry weight (45.6%). These results sug gest that incorporation of rice residues of tested varieties has influence on controlling barnyardgrass seedling
growth.
