Effect of crop-establishment methods and weed-management options on weed dynamics and productivity of rice (Oryza sativa)

A field experiment was conducted at the Norman E. Borlaug Crop Research Centre, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during the rainy (kharif) seasons of 2011 and 2012, to study the effect of crop-establishment methods and weed-management options on weed dynamics and productivity of rice (Oryza sativa L.). The lowest density and dry matter of total weeds 60 days after sowing/days after transplanting was recorded under transplanted rice. This treatment resulted in the highest number of effective tillers/m² (218.36) and grain yield (4.01 t/ha) of rice. Among the weed-management options, application of bispyribac sodium 20 g/ha at 15 DAS/DAT followed by 1 hand-weeding (HW) at 35 DAS/DAT being at par with the application of penoxsulam 22.5 g/ha at 2-3-leaf stage of weeds, followed by 1 HW at 35 DAS/DAT recorded the minimum population and dry-matter of total weeds and the highest weed control efficiency. This treatment resulted in significantly higher number of panicles/m², grains/panicle and grain yield than rest of the treatments. Crop-establishment methods and weed-management options interacted significantly; and significantly higher grain yield was recorded with transplanted rice in combination with the application of bispyribac sodium 20 g/ha at 15 DAS/DAT followed by 1 HW at 35 DAS/DAT or penoxsulam 22.5 g/ha at 2-3-leaf stage of weeds followed by (fb) 1 HW at 35 DAS/DAT. The highest net returns ( 1, 380/ha) and benefit: cost ratio (1.09) were recorded with application of penoxsulam 22.5 g/ha at 2-3-leaf stage of weeds fb 1 HW at 35 DAS/DAT.