WEED MANAGEMENT IN BLACK GRAM AND RESIDUAL EFFECT OF HERBICIDES ON SUCCEEDING MUSTARD CROP
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Date
2018
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Birsa Agricultural University, Ranchi, Jharkhand-6
Abstract
Black gram is one of the important pulse crops grown in India as it contributes 24 per cent of total kharif pulses production. A high level of weed infestation poses a major problem in kharif black gram. Weeds being a serious negative factor in crop production are responsible for marked loss (27-90%) in black gram yield. Therefore, weed control plays an important role in black gram production to achieve a desired level of yield. Judicious use of herbicides with its proper dose, method and time of application has to be taken care of with view that not only weeds in black gram are controlled effectively but also should not leave residual toxic effect on succeeding crops. Keeping these points in view, an experiment entitled “Weed management in black gram and residual effect of herbicides on succeeding mustard crop” was conducted at Birsa Agricultural University, Ranchi, Jharkhand during rainy & winter seasons of 2015-16 and 2016-17. The experimental soil was sandy-loam in texture with low organic carbon (0.33 %), moderately acidic (pH 5.5) in nature, low available nitrogen (185.30 kg/ha), medium phosphorus (21.32 kg/ha), medium potassium (161.28 kg/ha) and high sulphur (11.50 kg/ha) content. The experiment was laid out in randomized block design with 12 treatments i.e. haloxyfop 81 g/ha, haloxyfop 108 g/ha, haloxyfop 135 g/ha, haloxyfop 270 g/ha, fenoxaprop-p-ethyl 61.9 g/ha, quizalofop-ethyl 43.8 g/ha, imazethapyr 100 g/ha each applied at 20 DAS, pendimethalin 1000 g/ha, oxyfluorfen 100 g/ha both applied at 3 DAS, two mechanical, two hand weeding each performed at 25 and 45 DAS and weedy check, replicated thrice. Black gram var. Birsa Urd-1 was sown at 30 cm using 30 kg seed/ha fertilized with recommended level of nutrients N:P2O5:K2O:S i.e. 25:50:25:25 kg /ha. Mustard var. Pusa-Bold was sown at 30 cm using 5 kg seed/ha fertilized with recommended level of nutrients N:P2O5:K2O:S i.e. 80:40:20:20 kg/ha.
Results revealed that two hand weeding at 25 & 45 DAS was found most effective in reducing weed density and weed dry weight followed by two mechanical weeding at 25 & 45 DAS i.e. 81.69 and 68.77 per cent, respectively as compare to weedy check. Two hand weeding at 25 & 45 DAS recorded higher crop dry weight, LAI, number of pods/plant, seed yield and harvest index to the extent of 44.07, 22.70, 28.90, 104.09 and 38.87 per cent, respectively as compare to weedy check i.e. 212.17 g/m2, 3.37, 10.72 pods/plant, 621 kg/ha and 19.15 per cent, respectively. However, application of haloxyfop 108 g/ha at 20 DAS recorded ` 10,513 and ` 13,878/ha higher net return compared to conventional practice of weed control i.e. two hand weeding at 25 & 45 DAS (` 26,789/ha) and two mechanical weeding at 25 & 45 DAS (` 23,421/ha), respectively and also recorded maximum B: C ratio (1.56). Haloxyfop 135 g/ha, haloxyfop 270 g/ha, imazethapyr 100 g/ha each applied at 20 DAS, pendimethalin 1000 g/ha and oxyfluorfen 100 g/ha each applied at 3 DAS had phytotoxic effect on black gram crop. Residues of herbicides were below detectable limit (˂ 0.02 mg/kg) in plant parts of black gram as well as in soil at maturity stage. Two hand weeding at 25 & 45 DAS recorded maximum nutrient N, P & K uptake by grain (46.62, 6.40 & 19.23 kg/ha) & straw (32.68, 1.88 & 28.97 kg/ha) of black gram crop and minimum removal by weeds (29.42, 7.27 & 27.43 kg/ha, respectively). In succeeding crop, no phyto-toxic effect was observed by any herbicides. The weed density their dry weight, yield and economics in succeeding mustard crop remain unaffected by weed control methods performed in black gram. Two hand weeding at 25 and 45 DAS recorded maximum black gram equivalent yield however, application of haloxyfop 108 g/ha at 20 DAS recorded maximum net return and benefit: cost ratio of black gram–mustard cropping system.
It can be summarized that either two hand weeding at 25 & 45 DAS or two mechanical weeding at 25 & 45 DAS was most effective in reducing weed density, weed dry weight & recorded maximum crop growth and yield of black gram. Among herbicides, haloxyfop 108 g/ha at 20 DAS recorded maximum crop growth, yield, net return and benefit: cost ratio of black gram. Weed control method performed in black gram did not influence weed, yield and economics in succeeding mustard crop.
Based on the results of present investigation, it can be concluded that application of haloxyfop 108 g/ha at 20 DAS can be recommended as an economical weed control methods in black gram for obtaining higher productivity without causing phyto-toxic effect on black gram as well as on succeeding mustard crop.
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WEED MANAGEMENT IN BLACK GRAM AND RESIDUAL EFFECT OF HERBICIDES ON SUCCEEDING MUSTARD CROP
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