Integrated weed management practices in dry direct-seededsummer rice (Oryza sativa)

Abstract

A field experiment was carried out during summer of 2007 and 2008 to work out integrated weed management practices with its economics in dry direct-seeded summer rice (Oryza sativa L.). Among the weed flora, grasses, like Bermudagrass [Cynodon dactylon (L.) Pers.], Jungle rice [Echinochloa colona (L.) Link], Large crabgrass [Digitaria sanguinalis (L.) Scop.], Signalgrass [Brachiaria ramosa (L.) Stapf]; sedges, like Cyperus pilosus L., Flatsedge (Cyperusiria L.) and broad-leaved weeds, like Spiny amaranth (Amaranthus spinosus L.), Black nightshade (Solanum nigrumL.), Garden spurge (Euphorbia hirta L.), Commelina diffusa Burmp., Gripe weed (Phyllanthus niruri Hook.f.), Commonlambsquarters (Chenopodium album L.), Alternanthera sp., Ground cherry/Hogweed (Physalis minima L.) and several species of Polygonum was noticed during experimentation. The concept of brown manuring in which seeding of dhaincha(Sesbania rostrata Brem) with rice seeds, followed by 2,4–D application @ 0.50 kg/ha at 25 days after sowing and subsequent incorporation of dried dhaincha with rotary weeder at 35 days after sowing, has been used in integrated weed management. Among the integrated weed management practices, butachlor @ 1.25 kg/ha as pre-plant surface application + brown manuring + 2,4–D @ 0.50 kg/ha at 40 days after sowing recorded highest grain yield (4.36 and 4.18tonnes/ha) and it was significantly at par with the grain yield (4.53 and 4.31 tonnes/ha) obtained from season-long weed-free situation. Highest net returns (Rs 21 954 and 20 494/ha) and benefit:cost ratio (1.30 and 1.22) was also recorded in this treatment during both the years.