Effect of herbicides on weed infestation and yield in boro rice

Abstract

A field experiment was conducted at the agronomy field of the Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh, Bangladesh, under wet land condition during December 2014 to May 2015. The aim was to see the effects of the weed control treatments on crop growth and yield in boro rice. Five selected herbicides (Metsulfuron-methyl 20 WG at 50 g/ha, pretilachlor 500 EC at 988 ml/ha, bensulfuran methyl 4%+acetachor 14% 18 WP at 800 g/ha, pyrazosulfuron-ethyl 10 WP at 125 g/ha and butachlor 5G at 25 kg/ha) were tested along with two hand weedings. Population density, fresh and dry weight of weed were taken. Eight weed species belonging to five families, namely, Echinochloa colonum, Paspalums crobiculatum, Monochoria vaginalis, Leersia hexandra L., Scirpus mucronatus L., Digitaria sanguinalis, Cyperus rotundus and Eclipta alba Hassk were found to grow in the experimental plots. Among the weed control treatments highest grain yield (5.73 t/ha) was produced with the treatment pyrazosulfuron-ethyl 10 WP at 125 g/ha followed by two hand weedings (5.50 t/ha). The increased yield due to application of herbicide contributed mainly from increasing the number of total tillers per plant, effective tillers per plant, filled grains per panicle and 1000-seed weight (g). Maximum benefit : cost ratio with pyrazosulfuron-ethyl 10 WP at 125 g/ha suggested that this herbicidal treatment could be used as an alternative when labour was a limiting factor in producing transplant boro rice.