Efficacy of certain new herbicide formulations in transplanted rice under rainfed shallow lowland.

摘要

The efficacy of butachlor (938 g/ha), pretilachlor (500 or 750 g/ha), bensulfuron methyl (40 or 50 g/ha), bensulfuron methyl [bensulfuron] (40 or 50 g/ha) + butachlor (938 g/ha), and hand weeding 2 (20 and 40 days after transplanting or DAT) or 3 (20, 40 or 60 DAT) times against weeds infesting rice (cv. Gayatri) was evaluated in Cuttack, Orissa, India, during the rainy seasons of 2002 and 2003. The weeds in the experimental area were Echinochloa colona, E. crus-galli, Cyperus iria, Fimbristylis miliacea, Scirpus articulatus, Panicum repens, Leptochloa chinensis, Sphenoclea zeylanica, Ludwigia parviflora, Aeschynomene indica, Limnophila heterophylla, Cleome viscosa, Monochoria vaginalis and Melochia corchorifolia. All treatments significantly reduced weed dry matter and density. Hand weeding 3 times was more effective than the herbicides for weed control. Among the herbicides, pyrazosulfuron ethyl at 25 g/ha resulted in the lowest weed density (11/m2) and dry weight (9.1 g/m2) in 2002. In 2003, weed density (17/m2) and dry weight (13.4 g/m2) were lowest with bensulfuron methyl (50 g/ha) + butachlor (938 g/ha). The reduction in grain yield due to weed infestation reached 34 and 37% during 2002 and 2003, respectively. The highest grain yields were obtained with pyrazosulfuron ethyl (5.65 t/ha) in 2002, and with bensulfuron methyl (50 g/ha) + butachlor (938 g/ha), and hand weeding 2 or 3 times in 2003 (5.60, 5.70 and 5.79 t/ha, respectively)..