Weed management in direct seeded unpuddled rice (Oryza sativa l.) under different sowing dates
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Date
2008-01
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
A field experiment entitled ´Weed management in direct seeded unpuddled rice (Oryza sativa L.) under different sowing datesµ was conducted during kharif season of 2006 and 2007 at Crop Research Centre of G. B. Pant University of Agriculture and Technology, Pantnagar district U.S. Nagar (Uttarakhand) to evaluate the efficacy of different herbicides viz. butachlor @ 1.5 kg ha-1 (PE), pendimethalin @ 1.5 kg ha-1 (PE), pendimethalin @ 1.0 kg ha-1 + anilophos @ 0.4 kg ha-1 (PE), thiobencarb @ 1.5 kg ha-1 (PE), pretilachlor @ 0.75 kg ha-1 (PE), fenoxaprop-p-ethyl @ 0.06 kg ha-1(15 DAS) followed by 2,4-D @ 0.5 kg ha-1 (30 DAS), anilophos @ 0.4 kg ha1 (10 DAS) and two hand weedings (20 and 40 DAS) under different sowing dates viz. 05 June, 20 June and 05 July and their effects on weeds, crop growth, yield and economics of rice. Weed free and weedy check were also included in the experiment. The field experiment was laid out in split-plot design with 3 replications. Rice variety ´Govindµ was sown in lines at 20 cm distance with recommended dose of fertilizer 120 kg N, 80 kg P2O5 and 60 kg K2O per hectare. Echinochloa colonum among grasses, Commelina benghalensis and Caesulia axillaris among non-grasses and Cyperus rotundus among sedges were the predominant weeds in experimental field. Uncontrolled weeds in weedy check plots caused on an average reduction in grain yield by 74.41 percent during 2006 and 67.43 percent during 2007 over weed free plots. The lowest weed population and dry weight were recorded in 05 July sown crop over rest of two sowing dates (05 June & 20 June). Highest yield attributes, grain yield (2488.5 kg ha-1 during 2006 and 2703.3 kg ha-1 during 2007) and nutrients uptake by crop plants was recorded in 20 June sown crop. Pre-emergence application of pendimethalin @ 1.0 kg ha-1 + anilophos @ 0.4 kg ha-1 and two hand weedings (20 and 40 DAS) produced highest grain yield during both the years. Pendimethalin @ 1.5 kg ha-1 and fenoxaprop-p-ethyl @ 0.06 kg ha-1 followed by 2,4-D @ 0.5 kg ha-1 also gave effective control of weeds and higher grain yield. Pendimethalin @ 1.0 kg ha-1 + anilophos @ 0.4 kg ha-1 applied one day after sowing found superior over all other herbicidal treatments in reducing population and dry matter of weeds and it lead to highest grain yield which ultimately fetched highest net return during both the years.
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