AGRICULTURAL RESEARCH COMMUNICATION CENTRE www.arccjournals.com/www.ijarjournal.com *Corresponding author’s e-mail: jaiprakashbhimwal@gmail.com Indian J. Agric. Res., 52(6) 2018: 681-685 Print ISSN:0367-8245 / Online ISSN:0976-058X Performance of different tank mix herbicides for broad-spectrum weed control in soybean [Glycine max (L.) Merrill] Jai Prakash Bhimwal*, Arvind Verma, Versha Gupta, S. K. Meena and B. D. Malunjkar Department of Agronomy, Rajasthan College of Agriculture, Udaipur Maharan Pratap University of Agriculture and Technology- Udaipur-313 001, Rajasthan, India. Received: 10-08-2018 Accepted: 03-10-2018 DOI: 10.18805/IJARe.A-5107 ABSTRACT A field experiment was conducted at the Rajasthan College of Agriculture, Maharana Pratap University of Agriculture and Technology -Udaipur during Kharif season 2015 and 2016 to test the efficacy of different herbicide and herbicide mixtures against weeds in soybean. Monocot weeds were predominant (57.68 %) in the experimental field compared to Broad leaved weeds (42.31 %). However, Echinochloa colona (40.55 %) and Corchorus olitorius (23.68%) were dominant in soybean at 30 DAS. Among different weed control treatments, post-emergence and tank mix combination of propaquizafop + imazethapyr (75+75 g ha -1 ) and imazethapyr + quizalofop-ethyl (75+60 g ha -1 ) at 21 DAS were most effective in respect of reducing weed density, weed biomass, nutrient removal by weed and improving yield attributes, yield and quality of soybean compared to other treatments. Highest seed yield (2271 kg ha -1 ), Haulm yield (3127 kg ha -1 ) of soybean and maximum net return ( 51550/ha) were also recorded with propaquizafop 75 g ha -1 + imazethapyr 75 g ha -1 followed by imazethapyr + quizalofop-ethyl (75+60 g ha -1 ). Further, they were also found responsible for highest uptake of N, P and K in soybean and lowest uptake of these plant nutrients by weeds. Key words: Imazethapyr, Propaquizafop, Quizalofop-ethyl, Soybean, Weed, Yield. INTRODUCTION Soybean [Glycine max (L.) Merrill] is one of the most important oilseed crops in India (Jaybhay et al. 2018). The crop is called “Golden bean” or “Miracle crop” of the 21 st century because of its multiple uses (Jadhav 2014). Soybean serves as a good source of protein (40-42 %) and oil (18-20 %) with tremendous ability to fix atmospheric nitrogen for soil improvement (Jain et al. 2018). India is the fourth and fifth largest country in the world with respect to soybean area and production, respectively. On the national basis, during the year 2015-2016, soybean occupied an area of 11.67 m ha with production and productivity of 8.59 million tonnes and 737 kg ha -1 , respectively (Agricultural Statistics, 2016). Soybean is a rainy season crop so it suffers severely due to weed infestation, resulting reduction in yield to the tune of 20 to 71% depending upon the type and intensity of weeds and their occurrence (Parmar et al., 2016). Unavailability of labour and high wages during wet season are the main limitations of manual weeding whereas, sole application of herbicide as pre or post emergence fails to control diversified and subsequent flushes of weeds effectively (Tuti and Das 2011). Moreover, continuous use of single herbicide is known to result in herbicide resistance in weed species and shift in weed flora. There is need to apply some new post-emergence herbicides and their tank mix combinations like imazethapyr, propaqizafop, quizalofp- ethyl and chlorimuron-ethyl to reduce weed menace and keep the crop free from weed competition during entire critical period of crop growth (Sandil et al., 2015; Parmar et al., 2016 Nirala et al., 2016). Therefore, the experiment was aimed to find out the efficacy of different tank mix and alone herbicides on weeds and yield of soybean. MATERIALS AND METHODS The field experiment was conducted during rainy season (kharif) of 2015 and 2016 at agriculture research farm, Rajasthan College of Agriculture (altitude of 582.17 meter above mean sea level with 24 º 35’ N latitude and 74°42’ E longitude), Maharana Pratap University of Agriculture & Technology, Udaipur. The experimental soil was well drained, alluvial in nature and clay loam in texture, having pH 7.8, OC 0.75%, available nitrogen 370 kg ha -1 , available phosphorus 24 kg ha -1 and available potassium 421 kg ha -1 respectively which was estimated by methods prescribed by Jackson, (1967). The experimental site belongs to the semi arid climate, the temperature of the experimental period was moderate, ranges from 16.6 to 35.9°C and the mean annual rainfall of the region was 637 mm and maximum and minimum relative humidity was 95% and 30% respectively. The experiment was laid out with eleven treatments comprising of weedy check (T1), two hand weeding at 15 and 35 DAS (T2), Pendimethalin 1000 g ha -1 at pre- emergence (T3), post-emergence application of Quizalofop- ethyl 75 g ha -1 at 15 DAS (T4), Imazethapyr 100 g ha -1 PoE at 15 DAS (T5), Chlorimuron-ethyl 10 g ha -1 PoE at 21 DAS (T6), Propaquizafop 100 g ha -1 PoE 15 DAS (T7), tank mix