Influence of crop establishment methods and weed management practices on yield and economics of direct-seeded rice (Oryza sativa)

A field experiment was conducted during the rainy season of 2006 and 2007 to study the bio-efficacy of various herbicides on weeds, yield and economics of direct seeded rice. The weed flora emerged during experimentation were: grasses like Echinochloa colonum, Echinochloa crusgalli, Cynodon dactylon; sedges like Cyperus rotundus, Cyperus iria, Fimbristylis miliaceae; and broad-leaved weeds like Eclipta alba and Ceasulia oxilaris. Rice established by drum seeding method had minimum density of grasses, sedges and broad-leaved weeds and dry weight of grasses (6.18 and 8.77 g/m²), sedges (3.32 and 4.97 g/m²), broad-leaved weeds (1.85 and 2.74 g/m²) at 45 and 60 DAS, N-P-K (4.09–1.53–4.49 kg/ha) uptake by weeds and maximum weed control efficiency (67.02%), grain yield (4.55 t/ha), net return (Rs 24,520) and benefit: cost ratio (1.76). Application of pretilachlor (0.75 kg a.i./ha pre-emergence) followed by 2,4-D (0.50 kg a.i./ha post-emergence) proved to be most effective in minimizing the density of weeds and their dry weight, and in enhancing the weed control efficiency (84.24%), grain yield (4.73 t/ha), N-P-K uptake by crop, net return (Rs 26,110) and benefit: cost ratio (1.92).