Vol. 11, Special Issue 4 (2022)

Author(s):
G Manisankar, T Ramesh, S Rathika, P Balasubramaniam and P Janaki

Abstract:
The experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute, Tiruchirappalli, Tamil Nadu during Rabi (2018-19) to analyse the economic impact of herbicidal weed management in transplanted rice. The experiment was laid out in split plot design with four main plot, five sub plot treatments and replicated thrice. Main plot treatments were pre plant application of herbicides namely glyphosate 2.5 kg ha^-1, glufosinate ammonium 1.0 kg ha^-1, halosulfuron methyl 67.5 g ha^-1 and control. Sub plot treatments consisted of different weed management practices in transplanted rice namely pre emergence application of bensulfuron methyl + pretilachlor 660 g ha^-1 on 3 DAT + one hand weeding on 45 DAT, post emergence application of bispyribac sodium 25 g ha^-1 on 15 DAT + one hand weeding on 45 DAT, pre emergence application of bensulfuron methyl + pretilachlor 660 g ha^-1 on 3 DAT + post emergence application of bispyribac sodium 25 g ha^-1 on 25 DAT, hand weeding twice at 25 and 45 DAT and unweeded control. The pre plant herbicides are sprayed at 15 days before puddling. Economic analysis was carried out by working of gross return, net return, benefit cost ratio and partial budgeting in relation to each weed control treatments. Pre plant application of glyphosate 2.5 kg ha^-1 recorded significantly higher weed control efficiency (88.3%), grain yield (4232 kg ha^-1), gross return (₹ 90154 ha^-1), net return (₹ 54391 ha^-1) and B:C ratio (2.51) than halosulfuron methyl and control. These results are closely followed by application of glufosinate ammonium 1.0 kg ha^-1. Among the weed management practices followed in rice, hand weeding twice at 25 and 45 DAT registered higher weed control efficiency (96.4%) at 60 DAT. This was on par with application of bensulfuron methyl + pretilachlor 660 g ha^-1 on 3 DAT + bispyribac sodium 25 g ha^-1 on 25 DAT, post emergence application of bispyribac sodium 25 g ha^-1 on 15 DAT + one hand weeding on 45 DAT. Post emergence application of bispyribac sodium 25 g ha^-1 on 15 DAT + one hand weeding on 45 DAT registered significantly higher grain yield (4327 kg ha^-1), gross return (₹ 91550 ha^-1), net return (₹ 53298 ha^-1) and B:C ratio (2.40) than unweeded control. Partial budgeting revealed that pre plant application of glyphosate 2.5 kg ha^-1 gave additional benefit of ₹ 9885 ha^-1 over existing practice of control. Pre emergence application of bensulfuron methyl + pretilachlor 660 g ha^-1 on 3 DAT + bispyribac sodium 25 g ha^-1 on 25 DAT gave additional benefit of ₹ 5640 ha^-1 over existing practice of two hand weeding. Pre plant application of glyphosate 2.5 kg ha^-1 at 15 days before puddling followed by post emergence application of bispyribac sodium 25 g ha^-1 on 15 DAT + one hand weeding on 45 DAT not only reduced the cost of weeding (₹ 2975 ha^-1) but also gave higher net returns (₹ 3945 ha^-1) and additional benefit (₹ 5640 ha^-1) over existing practice of two manual weeding. Considering the present scenario of labour scarcity and higher rate of wages, herbicidal weed management in transplanted rice could be an economically viable option. Hence, it could be concluded from the field study, pre plant application of glyphosate 2.5 kg ha^-1 at 15 days before puddling followed by post emergence application of bispyribac sodium 25 g ha^-1 on 15 DAT + hand weeding on 45 DAT found better weed control efficiency, higher productivity, gross return, net return, benefit cost ratio and additional benefit in transplanted rice under sodic soil ecosystem.