Long-term sustainability in weed management for direct seeding of rainfed rice

Successful weed management for direct-seeded rice depends on herbicide use to protect crop yields from weed competition. In irrigated cropping environments,this has a tendency to lead to progressive changes in the weed flora toward intransigent competitive rice weeds. A four-year comparative study of direct seeding and transplanting in the Barind indicated that the weed flora was responsive to an alteration in crop establishment method but that the composition of the target weed community under all methods had significant similarity. This is argued to be a consequence of seasonal variation in rainfall and flooding regimes. The implications for developing sustainable weed management practices with the use of early postemergence herbicides are discussed.