Interactive effect of nitrogen and weed management on weeds and yield of aerobic hybrid rice (Oryza sativa L.)
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Date
2020-12
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
A field experiment entitled “INTERACTIVE EFFECT OF NITROGEN AND WEED MANAGEMENT ON WEEDS AND YIELD OF AEROBIC HYBRID RICE (Oryza sativa L.)” was conducted in D-3 block of Norman E. Borlaug Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar (Utttrakhand) during kharif season of 2019. The objectives of the investigation were to study the interactive effect of N and weed management on density and biomass accumulation of weeds, interactive effect of N and weed management on yield and yield attributes of aerobic hybrid rice and economics of N and weed management practices. The field experiment was laid out in a factorial randomized block design with four nitrogen levels viz. 0, 112.5, 150 and 187 kg N/ha in factor A and five weed management practices viz. weedy, weed-free, pendimethalin (1.0 kg a.i/ha) then Sesbania line sowing incorporation with cono weeder (30 DAS), pendimethalin (1.0 kg a.i/ha) fb ready mix of penoxsulam + cyhalofop (0.135 kg a.i/ha) at 20 DAS and Sesbania broadcasting fb pendimethalin (1.0 kg a.i/ha) fb brown manuring with 2,4-D (0.5 kg a.i/ha) + 1 HW at 45 DAS in factor B and replicated three times. Cyperus iria, Cyperus difformis, Echinochloa colona, Echinochloa crus-galli, Celosia argentea and Phyllanthus niruri were the major weed species. Integrated approaches Sesbania fb pendimethalin fb brown manuring with 2,4-D and 1 hand weeding with every nitrogen level recorded lowest weed density, weed dry matter, highest weed control efficiency and lowest weed index after weed free treatment at 30, 60 and 90 DAS. The yield and yield attributing characters were influenced by different levels of nitrogen and weed management practices. Among the nitrogen levels, the maximum number of panicles/m2, number of grains/panicle and test weight were recorded with application of 187 kg N/ha which was significantly higher than the 150, 112.5 and 0 kg N/ha. After weed free treatment, Sesbania broadcasting fb pendimethalin fb brown manuring with 2,4-D + 1 hand weeding recorded maximum number of panicles/m2, number of grains/panicle and test weight. The maximum grain yield was recorded with application of 187 kg N/ha which was significantly higher than the 112.5 and 0 kg N/ha but statistically at par with 150 kg N/ha. Among weed management practices, weed free recorded highest grain yield (4996 kg/ha) followed by integrated approach i.e., Sesbania broadcasting fb pendimethalin fb brown manuring with 2,4-D + 1 hand weeding than other treatments. The highest net returns and benefit cost ratio (2.57) were recorded with integration of N level 150 kg/ha and Sesbania fb pendimethalin fb brown manuring.