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

Abstract

A field experiment was conducted at the Norman E. Borlaug Crop Research Centre, Govind Ballabh Pant Uni- versity 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 produc- tivity 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 23-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-es- tablishment 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 23-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 23-leaf stage of weeds fb 1 HW at 35 DAS/DAT.