Abstract

                                A field experiment was conducted from September 2011 to January 2012 at Tamil Nadu Agricultural University, Coimbatore to study the influence of pre and post plant herbicidal weed management on yield attributes, yield and economics in transplanted rice. The experiment was laid out in a Factorial randomised block design with three replications and two factors viz. pre-plant herbicide application (with and without glyphosate at 0.75 kg a.i ha- 1) and pre emergence / early post emergence herbicide treatments consisting pre-emergence butachlor 1.25 kg a.i ha-1, pretilachlor 0.75 kg a.i ha-1, almix 20 g ha-1 on 3 days after transplanting followed by hand weeding at 40 DAT, early post emergence Bensulfuron methyl + pretilachlor (6.6 GR) @ 0.06+0.60 kg a.i ha-1 at 10 DAT, hand weeding twice at 20 and 40 DAT and unweeded control. The results revealed that pre-plant application of glyphosate resulted in higher number of productive tillers m-2 (440), more grains panicle-1 (121), increased panicle length (23.99 cm), increased panicle weight (2.60 g) and higher yield (5766 kg) and net returns (Rs 25,188 ha-1) compared to non glyphosate application. Among the post plant weed management methods, number of productive tillers m-2, grains panicle-1, panicle weight, grain yield and net returns were higher in EPOE application of Bensulfuron methyl + pretilachlor (6.6 GR) @ 0.06 + 0.60 kg a.i ha-1 at 10 DAT (498m-2, 11g, 24.56 cm, 2.71 g, 6100 kg ha-1 and Rs 33,120 ha-1, respectively), followed by pretilachlor at 0.75 kg a.i ha-1 + HW at 40 DAT and HW twice at 20 and 40 DAT, which were comparable .

Key words : Rice, pre-plant glyphosate, bensulfuron methyl + pretilachlor, yield attributes, grain yield, economics.