Microsoft Word - BAJ 360C__Press Bangladesh Agron. J. 2020, 23(1): 83-89 IMPACT OF INTEGRATED WEED MANAGEMENT ON BULB YIELD OF ONION M.R. Islam1, M. Moniruzzaman2, A.J.M. Obaidullah1 and A.H.F. Fahim3 1S.O., RSRC, BARI, Magura, 2S.S.O., RSRC, BARI, Magura, 3S.O., SRC, BARI, Bogura Corresponding E-mail: rislamriaz@gmail.com (Received: 12 May 2020, Accepted: 17 July 2020) Keywords: Onion, BARI Piaz-1, weed, oxadiazon Abstract The experiment was conducted at Regional Spices Research Centre, Bangladesh Agricultural Research Institute, Magura, Bangladesh during 2016-2017 and 2017- 2018 to optimize weed management practice for onion bulb production through Integrated Weed Management (IWM). The experiment was laid out in a Randomized Complete Block Design with three replications. Two different herbicides (Oxadiazon and Pendimethalin) with different doses in combination with hand weeding (HW) were used as treatments. The total number of treatments were 12 viz. T1=Oxadiazon@1.0 l/ha, T2=Oxadiazon@1.5 l/ha, T3= Oxadiazon@2.0 l/ha, T4= Oxadiazon@1.0 l/ha + one HW at 45 DAT (Days After Transplanting), T5= Oxadiazon@1.5 l/ha + one HW at 45 DAT,T6= Oxadiazon@2.0 l/ha + one HW at 45 DAT, T7=Pendimethalin@1.0 l/ha, T8=Pendimethalin@1.5 l/ha, T9= Pendimethalin@1.0 l/ha + HW at 45 DAT, T10= Pendimethalin@1.5 l/ha+ HW at 45 DAT, T11= Weed free and T12 = Weedy check (control). The onion var. BARI Piaz-1 was used as the test crop. The highest bulb yield (7.63 tha-1 in 2016 & 9.56 t ha-1in 2017) and benefit cost ratio (2.14 in 2016 and 2.46 in 2017) were obtained from T6= Oxadiazon@2.0 l/ha + one hand weeding at 45 DAT while the lowest bulb yield (4.22 t ha-1in 2016 and 6.28 t ha-1in 2017) was obtained from T12 = Weedy check (control), while lowest benefit cost ratio (1.33 in 2016 and 1.74 in 2017) from treatment T11 =Weed free. It was concluded that Oxadiazon@2.0 l/ha with one hand weeding at 45 days after transplanting performed better for controlling weed and maximizing bulb yield of onion. Introduction Onion (Allium cepa L.) belongs to the family Alliaceae, a group that includes bulb crops. It is a condiment crop consumed fresh and dry as a spice and one of the most important vegetable crops in the world (Ray and Yadav, 2005). Onion is a very important and major spice crop in Bangladesh. It ranks the first in production among the spices crops cultivated in the country. About 17, 37, 714 matric tones of onion produces from 4, 41, 105 acres of land during 2017- 18 (BBS, 2018). Weeds are one of the main plant protection problems in onion fields. They compete with onions for light, nutrients, water, space and also are host plants of several harmful insects and pathogens (Dunan et al., 1996, Kizilkaya et al., 2001, Ghoshel, 2004, Qasem, 2006, Smith et al., 2008). As in many crops, weeds cause yield reduction in onions owing to slow emergence, low initial growth rate, long vegetative period and low competitive ability of the crop (Boyham et al., 2016). Onion is poor competitor against weeds due to their slow, vertical growth that fails to shade out weeds (Kizilkaya et al., 2001). Uncontrolled weed growth caused 84 Islam et al. 49 to 86 percent reduction in bulb yield of onion compared with the best herbicidal treatment (James and Harlen, 2010). Lack of effective and economically viable weed management options for onion production has been reported as a critical constraint affecting farmers' motivation to grow the crop (Waiganjo, 2004). The conventional method of weed control i.e. hand weeding and hoeing are vary laborious, time consuming and expensive. Weedicides applied at the pre- emergence stage, significantly controlled the weed population (Nargis et al., 2006). Panse et al. (2014) reported that post–emergence herbicides kill weeds and keep the hardy weeds under control by arresting their growth through various kinds of deformities in foliage and growing points. On the other hand, Patel et al. (2012) was found that the application of pre-emergence herbicide followed by one hand weeding was effective for higher yield of onion. For controlling weed, integrated management through cultural, mechanical and herbicidal methods could be more efficient than single methods because onion is a narrow leafed crop and the herbicides which do not herm onion also may not herm the narrow leafed weed. Therefore, the present study was undertaken to optimize weed management practice for onion bulb production through Integrated Weed Management (IWM). Materials and Methods The experiment was conducted at Regional Spices Research Centre, Bangladesh Agricultural Research Institute, Magura during the year 2016-2017 and 2017-2018. The land was medium high land and clay loam in texture having pH of7.55. The unit plot size was 3.0 m x 1.5 m. The most popular onion variety BARI Piaz-1 was used with 42 days old seedlings. The crop was transplanted maintaining 15 cm x 10 cm spacing. The experiment was laid out in Randomized Complete Block Design with three replications. Two different herbicides (Oxadiazon and Pendimethalin) with different doses in combination with hand weeding (HW) were used as the treatment variables. The total number of treatments were 12 viz. T1= Oxadiazon@1.0 l/ha, T2=Oxadiazon@1.5 l/ha, T3= Oxadiazon@2.0 l/ha, T4 = Oxadiazon@1.0 l/ha + one HW at 45 DAT (Days After Transplanting), T5= Oxadiazon@1.5 l/ha + HW at 45 DAT,T6 = Oxadiazon@2.0 l/ha + HW at 45 DAT, T7 = Pendimethalin@1.0 l/ha, T8 = Pendimethalin@1.5 l/ha, T9 = Pendimethalin@1.0 l/ha + HW at 45 DAT, T10 = Pendimethalin@1.5 l/ha + HW at 45 DAT, T11 = Weed free and T12 = Weedy check (control). The fertilizers were applied in the form of Urea, Triple Super Phosphate (TSP), muriate of potash (MoP), gypsum at the rate of N120 P54 K75 S20 kg/ha respectively. Half of N, K and full dose of P and S were applied at the time of final land preparation and remaining N, K was top dressed into two equal splits at 25 and 50 days after transplanting (DAT). Four irrigations at 25 DAT, 45 DAT 70 DAT and 90 DAT were provided. The crop was harvested 110 days after transplanting. Data on plant height (cm), number of leaves per plant, number of weed per m2, neck diameter (cm), length of bulb (cm), diameter of bulb (cm), individual bulb weight (g) and yield (tha-1) were collected. The Benefit Cost Ratio (BCR) was calculated on the basis of prevailing local market price of onion bulbs and cost of inputs. Data on weed density (plantm-2), dry matter weight of weeds (gm-2) were recorded from the standing crop by using quadrat of 1m x 1m. Weed control efficiency (WCE) was calculated by using the following formula used by (Das, 2008). �����%� = � − � � �100 Where, DMC was dry matter weight of weeds in control plot and DMT was dry matter of weeds in treated plots. The recorded data on yield and other parameters were statistically analyzed by using Statitix10 software. The difference between the treatments means were judged by Duncan’s Multiple Range Test (DMRT) (Gomez and Gomez, 1984). Impact of Integrated Weed Management on Bulb Yield of Onion 85 Results and Discussion Effect on weed Different weed species were found in experimental plots. Among them, the prominent weed species were Cyperus rotundas, Chenopodium album, Cynodon dactylon, Amaranthus viridis, Amaranthus spinosus, Physalis heterophylla, Echinochloa crusgalli etc. Similar types of weed species were also reported in onion field (Karim et al., 2014, Naresh et al., 2002, Panse et al., 2014 and Syed and Malik, 2001). It was found that the weed density, dry weight of weed and weed control efficiency were varied significantly among the different treatment combinations (Table 1). The highest weed density (506.67 no. m-2 in 2016-17 and 596.67 no. m-2 in 2017- 18), dry weight of weed (280.44 g m-2 in 2016-17 and 307.29 g m-2 in 2017-18) and minimum weed control efficiency (0%) was found in weedy check (control) plot. Because under this treatment no weeding was done and the plot was allowed to grow weed naturally. In this situation the weed covered the whole plot prior to the onion seedlings establishment and started to take soil nutrients and natural resources such as soil moisture, sunlight etc. The lowest weed density (0 no. m-2), dry weight of weed (0 g m-2) and maximum weed control efficiency (100%) was found in weed free plot. Because under this treatment weeding was done immediately the weeds appear on the plot as a result there was no competition between crop and weed for soil nutrient and natural resources. Among the herbicidal treatments lowest weed density (26.67 no. m-2 in 2016-17 and 26 no. m-2 in 2017-18), lowest dry weight of weed (35.67 g m-2 in 2016- 17 and 36.46 g m-2 in 2017-18) and maximum weed control efficiency (87.27% in 2016-17 and 88.11% in 2017-18) was found from the application of Oxadiazon@2.0 l/ha with one hand weeding at 45 days after transplanting. That means Oxadiazon performed better than Pendimethalin in onion field for controlling weed. Similar results were also reported by Uygur et al. (2010). Table 1.Effect of different weed management treatment on weed Treatments Weed density (plant m-2) Dry weight of weed (g m-2) Weed control efficiency (%) 2016-17 2017-18 2016-17 2017-18 2016-17 2017-18 T1- Oxadiazon@1.0 l/ha 66.00 bc 54.00 bcd 85.45b 76.66bcd 69.53f 75.12f T2- Oxadiazon@1.5 l/ha 59.00 bcd 45.00 cd 77.07c 77.76bc 72.50e 74.68f T3- Oxadiazon@2.0 l/ha 54.00 cde 45.00 cd 70.49d 68.53d 74.85d 77.68d T4 - Oxadiazon@1.0 l/ha + HW at 45 DAT 47.00 de 51.00 cd 63.44ef 74.63bcd 77.37c 75.71ef T5- Oxadiazon@1.5 l/ha + HW at 45 DAT 43.00 e 37.00 cde 70.37d 55.15e 74.90d 82.04c T6 - Oxadiazon@2.0 l/ha + HW at 45 DAT 26.67 f 26.00 de 35.67g 36.46f 87.27b 88.11b T7 - Pendimethalin@1.0 l/ha 68.00 b 92.00 b 77.44c 54.84e 72.34e 82.13c T8 - Pendimethalin@1.5 l/ha 64.00 bc 64.00bcd 84.51b 80.06b 69.88f 73.92f T9- Pendimethalin@1.0 l/ha + HW at 45 DAT 50.67de 74.00 bc 68.54de 74.45bcd 75.56d 75.76ef T10 - Pendimethalin@1.5 l/ha + HW at- 45 DAT 56.00 bcd 52.00 cd 60.21f 70.63cd 78.51c 76.99de T11 - Weed free 0 g 0 e 0 h 0 g 100a 100a T12-Weedy check (control) 506.67a 596.67a 280.44a 307.29a 0.00 g 0.00 g Level of significance ** * ** ** ** ** CV (%) 8.23 24.81 4.47 6.47 1.29 1.49 In a column, means followed by the same letter did not differ significantly by DMRT. HW= Hand Weeding, DAT =Days after transplanting, * = 5% level of significance and ** = 1% level of significance. 86 Islam et al. Effect on growth parameters Growth characters of onion as influenced by different treatments revealed significant variations (Table 2). The longest plant (52.27 cm in 2016 and 52.36 cm in 2017), higher number of leaves per plant (6.87 in 2016 and 7.47 in 2017) and higher neck diameter (0.94cm in 2016 and 1.27cm in 2017) were recorded from the application of Oxadiazon@ 2.0 l/ha with one hand weeding at 45 days after transplanting. The shortest plant (45.00 cm in 2016 and 46.63cm in 2017), lower number of leaves per plant (5.07 in 2016 and 6.3 in 2017) and lowest neck diameter (0.68 cm in 2016 and 0.97cm in 2017) was recorded from weedy check (control) treatment. Because due to lacking of optimum environment under weedy condition all the growth parameters reduced and the crop has to survive competing with weeds. Similar results were reported by Uygur et al. (2010). Table 2. Effect of different weed management treatments on growth parameters of onion Treatments Plant height (cm) No. of leaves plant-1 Neck diameter (cm) 2016-17 2017-18 2016-17 2017-18 2016-17 2017-18 T1- Oxadiazon@1.0 l/ha 49.40 abc 48.58e 6.47 a 6.50f 0.89 a 1.00de T2- Oxadiazon@1.5 l/ha 50.20 abc 49.63d 6.27 a 6.63de 0.89 a 1.09bc T3- Oxadiazon@2.0 l/ha 50.07 abc 50.80c 5.60 ab 6.73d 0.79 ab 1.13b T4 - Oxadiazon@1.0 l/ha + HW at 45 DAT 51.40 a 50.62c 6.40 a 7.17b 0.90 a 1.23a T5- Oxadiazon@1.5 l/ha + HW at 45 DAT 49.60 abc 51.57b 6.60 a 7.27b 0.78 ab 1.27a T6 - Oxadiazon@2.0 l/ha + HW at 45 DAT 52.27 c 52.36a 6.87 a 7.47a 0.94 a 1.27a T7 - Pendimethalin@1.0 l/ha 48.13 c 48.60e 5.80 ab 6.60ef 0.74 ab 1.02cde T8 - Pendimethalin@1.5 l/ha 48.47 bc 48.69e 6.40 a 6.67de 0.81 ab 1.07cde T9- Pendimethalin@1.0 l/ha + HW at 45 DAT 51.20 ab 50.57c 6.40 a 7.03c 0.79 ab 1.09bc T10 - Pendimethalin@1.5 l/ha + HW at- 45 DAT 50.80 abc 51.26b 6.07 ab 7.20b 0.86 ab 1.13b T11 - Weed free 48.20 c 49.47d 6.47 a 6.70 de 0.82 ab 1.11b T12-Weedy check (control) 45.00 d 46.63f 5.07 b 6.30 g 0.68 b 0.97e Level of significance ** ** * ** ** ** CV (%) 3.52 2.65 10.12 8.64 9.26 13.46 In a column, means followed by the same letter did not differ significantly by DMRT. HW= Hand Weeding, DAT =Days after transplanting, * = 5% level of significance and ** = 1% level of significance. Effect on yield parameters The yield and yield contributing characters were varied significantly among the different treatment combinations (Table 3). The biggest bulb diameter (3.54 cm in 2016 and 4.7 cm in 2017), longest bulb (3.51cm in 2016 and 4.67cm in 2017), heaviest individual bulb (13.20 g in 2016 and 29.72 g in 2017) and highest bulb yield (7.63 tha-1 in 2016 and 9.56 t ha-1 in 2017) was recorded from the application of Oxadiazon@2.0 l/ha with one hand weeding at 45 days after transplanting. This is due to the effectiveness of Oxadiazon for controlling weed as well as proper timing of hand weeding. So, that the crop gets minimum crop weed competition and Impact of Integrated Weed Management on Bulb Yield of Onion 87 optimum growing environment. Similar results were recorded from Patel et al. (2012) and Uygur et al. (2010).The smallest bulb diameter (2.44 cm in 2016 and 2.88 cm in 2017), shortest bulb (3.09 cm in 2016 and 2.96 cm in 2017), lightest individual bulb (8.34g in 2016 and 19.01 g in 2017) and lowest bulb yield (4.22 t ha-1 in 2016 and 6.28 t ha-1 in 2017) were recorded from weedy check (control) treatment. Because, under weedy condition the growth parameters of onion such as height and number of leaves were reduced ultimately this lowers the accumulation of photosynthates on the bulb. Similar results on variation of onion yield due to different time of planting were also reported by Devulkar et al. (2015) and Misra et al. (2014). During the year 2017-2018, the bulb yield of onion was higher than the year 2016-2017, this was because of timely showing and transplanting of onion. Table 3. Effect of different weed management treatments on bulb yield and yield contributing characters of onion Treatments Bulb diameter (cm) Bulb length (cm) Single bulb weight (g) Bulb yield (t ha-1) 2016- 17 2017- 18 2016- 17 2017- 18 2016-17 2017- 18 2016- 17 2017- 18 T1- Oxadiazon@1.0 l/ha 3.10 ab 3.80ef 3.38 ab 3.93f 10.67 ab 28.66k 6.85abc 7.72ef T2- Oxadiazon@1.5 l/ha 3.11 ab 3.94d 3.40 ab 4.01e 11.23abc 30.43i 6.96abc 8.06de T3- Oxadiazon@2.0 l/ha 3.17 ab 4.14c 3.52 ab 4.18d 11.58 ab 34.73e 7.00abc 8.09d T4 - Oxadiazon@1.0 l/ha + HW at 45 DAT 3.27 ab 4.35b 3.61 a 4.33c 11.56 ab 38.45c 6.98abc 8.56bc T5- Oxadiazon@1.5 l/ha + HW at 45 DAT 3.08 ab 4.37b 3.58 a 4.55b 11.89abc 42.86b 7.04abc 8.89b T6 - Oxadiazon@2.0 l/ha + HW at 45 DAT 3.54 ab 4.75a 3.65 ab 4.67a 13.20abc 44.58a 7.63 a 9.56a T7 - Pendimethalin@1.0 l/ha 3.10 ab 3.75f 3.41 ab 3.84g 10.48 bc 29.72j 6.29 bc 7.55f T8 - Pendimethalin@1.5 l/ha 3.41 a 3.87de 3.42 ab 3.97ef 9.49 abc 31.61h 6.51 bc 7.67f T9- Pendimethalin@1.0 l/ha + HW at 45 DAT 3.12 ab 4.18c 3.74 a 4.15d 13.27 a 33.06g 7.29 ab 8.22cd T10 - Pendimethalin@1.5 l/ha + HW at- 45 DAT 3.19 ab 4.35b 3.51 ab 4.13d 12.24 ab 37.66d 6.92abc 8.57bc T11 - Weed free 2.85 bc 3.82ef 3.54 ab 3.76h 10.60 c 33.63f 6.07 c 7.44f T12-Weedy check (control) 2.44 c 2.87g 3.09 b 2.95i 8.34 d 19.01l 4.22 d 6.28g Level of significance ** ** * ** ** ** ** ** CV (%) 9.25 7.34 8.05 5.64 12.42 9.34 9.39 7.58 In a column, means followed by the same letter did not differ significantly by DMRT Test. HW= Hand Weeding, DAT =Days after transplanting, * = 5% level of significance and ** = 1% level of significance. Cost benefit analysis The economic performance of onion as influenced by different weed management practices are presented in the Table 4. The highest gross return as well as Benefit Cost Ratio (2.14 in 2016 and 2.46 in 2016) was found from the treatment T6 (Oxadiazon@2.0 l/ha + Hand at 45 DAT) and the lowest Benefit Cost Ratio(1.33 in 2016 and 1.74 in 2017) from treatment T11 (weed free). This is because hand weeding is very laborious than spraying of herbicides also expensive and time consuming. Similar results also reported by Panse et al. (2014). 88 Islam et al. Table 4. Economic performance of onion as influenced by different treatments Treatments Total cultivation cost(Tk. ha-1) Gross return (Tk. ha-1) BCR 2016-17 2017-18 2016-17 2017-18 2016-17 2017-18 T1- Oxadiazon@1.0 l/ha 115000 115000 239750 270200 2.08 2.35 T2- Oxadiazon@1.5 l/ha 118000 118000 243600 282100 2.06 2.39 T3- Oxadiazon@2.0 l/ha 121000 121000 245000 283150 2.02 2.34 T4 - Oxadiazon@1.0 l/ha + HW at 45 DAT 125000 131000 244300 299600 1.95 2.29 T5- Oxadiazon@1.5 l/ha + HW at 45 DAT 126000 134000 246400 311150 1.96 2.32 T6 - Oxadiazon@2.0 l/ha + HW at 45 DAT 125000 136000 267050 334600 2.14 2.46 T7 – Pendimethalin@1.0 l/ha 127000 128000 220150 264250 1.73 2.06 T8 - Pendimethalin@1.5 l/ha 130000 130000 227850 268450 1.75 2.07 T9- Pendimethalin@1.0 l/ha + HW at 45 DAT 133000 133000 255150 287700 1.92 2.16 T10 - Pendimethalin@1.5 l/ha + HW at- 45 DAT 135000 135000 242200 299950 1.79 2.22 T11 - Weed free 160000 150000 212450 260400 1.33 1.74 T12-Weedy check (control) 110000 125000 147700 219800 1.34 1.76 Urea-Tk. 16/kg, TSP-Tk. 15kg-1, MoP-Tk.15 kg-1, Gypsum- Tk. 10 kg-1, Zinc sulphate –Tk.100 kg-1, Boric acid-Tk. 100 kg-1, Labour- Tk. 400man-1day-1, Irrigation- 3000ha-1 irrigation-1, Leas value- Tk. 25000ha-1 for 5 months, Seed-1500 kg-1, Sale price-Tk. 30 kg-1 bulb in 2016 and Tk. 35 kg-1 bulb in 2017 . 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