Effect of Green Manuring and Herbicides on Weed Dynamics and Yield of Direct Seeded Rice
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Date
2020-12
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Sher-e-Kashmir University of Agricultural Sciences and Technology Jammu, J&K
Abstract
An experiment entitled, “Effect of Green Manuring and Herbicides on Weed Dynamics and Yield of Direct Seeded Rice” was conducted at the Research Farm, Chatha of SKUAST-Jammu during the Kharif season of 2019. The soil of the experimental site was sandy clay loam in texture, slightly alkaline in reaction, low in organic carbon and available nitrogen but medium in phosphorus and potassium. The experiment was laid out in Factorial Randomized Block Design with two factors and three replications. The first factor consisted of three green manuring crops viz. Sunnhemp, Dhaincha and Cowpea and a stale seedbed treatment and another factor consisted of three herbicidal treatments viz. pendimethalin 1 kg/ha as PE, bispyribac-sodium 25 g/ha at 25 DAS and pendimethalin 1 kg/ha as PE fb bispyribac-sodium 25 g/ha at 25 DAS and a weedy check treatment. After layout, green manuring crops were sown and incorporated into the soil at the age of 45 days. The rice crop variety Basmati-370 was sown on 16th June, 2019. Full dose of potassium and half dose of nitrogen were applied through inorganic sources of nutrients viz. MOP and Urea. The remaining nitrogen was top dressed in two equal splits at mid tillering and at panicle initiation stages. The recommended phosphorus (20 kg P2O5/ha) for Basmati-370 was applied to green manuring crops. Irrigation was applied at regular intervals in rice as per need. The pre-emergence herbicide was applied on same day after sowing of the crop and the post-emergence herbicide was applied at 25 DAS of the crop.
The major weed flora observed in the rice field were, Echinochloa spp. Dactloctenium aegyptium, Cucumis spp., Phyllanthus niruri, Cyperus rotundus, Cyperus iria. The crop was also found infested with Eclipta alba, Physalis mimima, Digitaria sanguinalis, Solanum nigrum and Cyanodon dactylon but these were less in number and denoted as other weeds. A weed control efficiency ranging from 40-58% was observed in different green manuring treatments. The highest value of growth parameters, grain and straw yield were recorded under sunnhemp green manuring. Significantly higher nutrient uptake by rice crop was recorded with green manuring of sunnhemp which was statistically at par with dhaincha.
Among the herbicidal treatments, application of pendimethalin 1 kg/ha as pre-emergence fb bispyribac-sodium 25 g/ha at 25 DAS recorded significantly highest grain, straw yields and nutrient uptake by rice, besides highest weed control and significant reduction in density and dry biomass of weeds .The significantly highest nutrient uptake by weeds was recorded in weedy check followed by pendimethalin 1 kg/ha as pre-emergence. The highest net returns (Rs. 57773/ha) were recorded in green manuring of sunnhemp but highest B: C ratio (1.57) was found with green manuring of dhaincha. In herbicidal treatments, pendimethalin 1 kg/ha as pre-emergence fb bispyribac-sodium 25 g/ha at 25 DAS fetched higher net return (Rs. 78710) with highest B: C ratio (2.12) followed by bispyribac-sodium 25 g/ha at 25 DAS (Rs. 71050) with B: C ratio (2.01). On the basis of interaction, highest grain yield of rice was recorded with green manuring of sunnhemp with application of pendimethalin 1 kg/ha as PE fb bispyribac-sodium 25 g/ha at 25 DAS which was statistically at par with green manuring of cowpea, dhaincha and stale seedbed in combination with pendimethalin 1 kg/ha as PE fb bispyribac-sodium 25 g/ha at 25 DAS and green manuring of cowpea, dhaincha in combination with bispyribac-sodium 25 g/ha at 25 DAS. Henceforth, based on the one year of investigation it can be safely concluded that stale seedbed in combination of pendimethalin 1 kg/ha as PE fb bispyribac-sodium 25 g/ha at 25 DAS recorded numerically highest benefit cost ratio followed by green manauring of dhaincha combination of bispyribac-sodium 25 g/ha at 25 DAS and these treatment combinations found suitable for weed management in direct seeded rice.
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Preferred for your work. Jamwal, S. 2020. Effect of Green Manuring and Herbicides on Weed Dynamics and Yield of Direct Seeded Rice. M.Sc. thesis, Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, India.