Energetics, productivity and weed control in different rice (Oryza sativa) establishment methods in North-Western Indo-Gangetic Plains

A field experiment was conducted at Punjab Agricultural University, Ludhiana (Punjab) during the rainy (kharif) season of 2009 and 2010, to study the effect of various establishment methods and weed-control treatments on weeds, crop growth, yield attributes and yield of rice (Oryza sativa L.). The experiment was laid out in a split-plot design with 5 establishment methods, i.e. dry-seeding with 3 different drills-zero till drill, modified furrow drill, conventional seed-cum-fertilizer drill in unpuddled soil, wet-seeding or manual broadcast in puddled soil and manual transplanting in puddled soil, and 4 weed-control treatments, viz. pre-emergence application of pendimethalin 0.75 kg/ha, sequential application of pendimethalin 0.75 kg/ha and bispyribac 0.025 kg/ha or azimsulfuron 0.02 kg/ha and weed-free in 4 replications. Weed biomass at harvesting, effective tillers and grain yield did not vary significantly among different establishment methods. At 60 days after sowing, 27% more plant height, 5.6% more number of tillers and 49% more crop biomass were recorded under direct seeding methods than transplanting method. More net returns (36, 660/ha) and energy output: input ratio (5.04) were recorded under dry seeding methods than wet seeding (28, 792/ha and 4.24) and puddled transplanted method (27, 305/ha and 4.47). The maximum grain yield (6.7 t/ha) was recorded under weed-free treatment which was statistically at par with sequential use of pendimethalin 0.75 kg/ha with bispyribac 0.025 kg (6.6 t/ha) or azimsulfuron 0.02 kg/ha (6.5 t/ha). Sequential application of pre-and post-emergence herbicides resulted in more benefit: cost ratio (1.66) and energy output: input ratio (5.32).